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  • Question 1 - A 16-year-old patient presents to his GP with concerns about his physical development....

    Correct

    • A 16-year-old patient presents to his GP with concerns about his physical development. The patient reports feeling self-conscious about his body shape and experiencing bullying at school. On examination, the patient is noted to have gynaecomastia and microorchidism. The patient is referred to a paediatrician, who subsequently refers the patient to the genetics team. As part of their assessment, the genetics team orders a karyotype.

      What karyotype results would be expected for this patient, given the likely diagnosis?

      Your Answer: Klinefelter syndrome (47,XXY)

      Explanation:

      Understanding Klinefelter’s Syndrome

      Klinefelter’s syndrome is a genetic condition that is characterized by an extra X chromosome, resulting in a karyotype of 47, XXY. Individuals with this syndrome often have a taller than average stature, but lack secondary sexual characteristics. They may also have small, firm testes and be infertile. Gynaecomastia, or the development of breast tissue, is also common in individuals with Klinefelter’s syndrome, and there is an increased risk of breast cancer. Despite elevated levels of gonadotrophins, testosterone levels are typically low.

      Diagnosis of Klinefelter’s syndrome is made through karyotyping, which involves analyzing an individual’s chromosomes. It is important for individuals with this condition to receive appropriate medical care and support, as well as genetic counseling for family planning.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 2 - A 28-year-old woman complains of amenorrhoea and galactorrhoea for the past six months....

    Incorrect

    • A 28-year-old woman complains of amenorrhoea and galactorrhoea for the past six months. She has not been taking any medication and has been in good health otherwise. A pregnancy test has come back negative. What would be the most suitable investigation for this patient?

      Your Answer: MRI pituitary

      Correct Answer: Prolactin concentration

      Explanation:

      Galactorrhoea and Prolactinomas

      Galactorrhoea is a condition where breast milk is secreted, commonly seen during pregnancy and the early postpartum period. However, if a pregnancy test is negative, it may indicate the presence of a prolactinoma. Prolactinomas are tumors that develop in the pituitary gland, which can be either small or large. These tumors cause symptoms such as menstrual disturbance, infertility, and galactorrhoea due to the secretion of prolactin. Macroprolactinomas can also cause visual field defects, headache, and hypopituitarism due to their mass effect on the pituitary gland. Women with prolactinomas tend to present early due to menstrual cycle and fertility issues, while men may present later.

      The diagnosis of prolactinomas is made by measuring serum prolactin levels and performing MRI imaging of the pituitary gland. Serum prolactin levels are typically several thousand, with a reference range of less than 690 U/L. Elevated prolactin levels can also be caused by pregnancy and lactation, hypothyroidism, and certain medications such as antipsychotics, anti-depressants, and anti-convulsants.

      The treatment for prolactinomas involves drugs such as bromocriptine or cabergoline, which work by inhibiting prolactin release through the dopamine system. These drugs can cause significant tumor shrinkage over several weeks and months of treatment. Patients are typically monitored with serum prolactin levels and MRI scans for several years while continuing the medication. Some patients may be able to stop the medication without any further issues, while others may experience a relapse and need to resume treatment.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 3 - A 45-year-old Caucasian male visits his doctor complaining of numbness in his extremities...

    Incorrect

    • A 45-year-old Caucasian male visits his doctor complaining of numbness in his extremities and tingling sensations around his mouth and lips. He has undergone a thyroidectomy in the past. During a complete cranial nerve examination, the physician observes facial muscle twitching upon tapping the patient's face.

      What is the reason for the facial muscle twitching observed during the examination?

      Your Answer: Increased irritability of peripheral nerves due to hyperkalaemia

      Correct Answer: Increased irritability of peripheral nerves due to hypocalcaemia

      Explanation:

      Chvostek’s sign is a facial twitch that occurs when the distribution of the facial nerve in front of the tragus is tapped. This sign is caused by increased irritability of peripheral nerves, which is often seen in cases of hypocalcemia. In fact, Chvostek’s sign is considered the most reliable test for hypocalcemia.

      Calcium homeostasis is the process of regulating the concentration of calcium ions in the extracellular fluid. This is important because calcium ions help stabilize voltage-gated ion channels. When calcium levels are too low, these ion channels become more easily activated, leading to hyperactivity in nerve and muscle cells. This can result in hypocalcemic tetany, which is characterized by involuntary muscle spasms. On the other hand, when calcium levels are too high, voltage-gated ion channels become less responsive, leading to depressed nervous system function.

      Understanding Hypoparathyroidism

      Hypoparathyroidism is a medical condition that occurs when there is a decrease in the secretion of parathyroid hormone (PTH). This can be caused by primary hypoparathyroidism, which is often a result of thyroid surgery, leading to low calcium and high phosphate levels. Treatment for this type of hypoparathyroidism involves the use of alfacalcidol. The main symptoms of hypoparathyroidism are due to hypocalcaemia and include muscle twitching, cramping, and spasms, as well as perioral paraesthesia. Other symptoms include Trousseau’s sign, which is carpal spasm when the brachial artery is occluded, and Chvostek’s sign, which is facial muscle twitching when the parotid is tapped. Chronic hypoparathyroidism can lead to depression and cataracts, and ECG may show a prolonged QT interval.

      Pseudohypoparathyroidism is another type of hypoparathyroidism that occurs when the target cells are insensitive to PTH due to an abnormality in a G protein. This condition is associated with low IQ, short stature, and shortened 4th and 5th metacarpals. The diagnosis is made by measuring urinary cAMP and phosphate levels following an infusion of PTH. In hypoparathyroidism, this will cause an increase in both cAMP and phosphate levels. In pseudohypoparathyroidism type I, neither cAMP nor phosphate levels are increased, while in pseudohypoparathyroidism type II, only cAMP rises. Pseudopseudohypoparathyroidism is a similar condition to pseudohypoparathyroidism, but with normal biochemistry.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 4 - A 29-year-old woman presents to her GP complaining of a tingling sensation around...

    Incorrect

    • A 29-year-old woman presents to her GP complaining of a tingling sensation around her mouth and intermittent cramps in her legs. Trousseau's sign is positive. Blood results are shown below.

      Urea 4.0 mmol/L (2.0 - 7.0)
      Creatinine 80 µmol/L (55 - 120)
      Calcium 1.95 mmol/L (2.1-2.6)
      Phosphate 1.2 mmol/L (0.8-1.4)
      Vitamin D 150 nmol/L (50-250)
      Parathyroid hormone (PTH) 1.7 pmol/L (1.6-8.5)

      Derangement of what substance may be responsible for this patient's presentation?

      Your Answer: Potassium

      Correct Answer: Magnesium

      Explanation:

      The correct answer is magnesium. Adequate levels of magnesium are necessary for the proper functioning of parathyroid hormone, which can lead to hypocalcemia if magnesium levels are low. Magnesium is also essential for PTH secretion and sensitivity. Amylase, chloride, and potassium are not associated with hypocalcemia. While severe pancreatitis may cause hypocalcemia, it is typically accompanied by other symptoms such as vomiting and epigastric pain. Chloride is not linked to hypocalcemia, and hypomagnesemia can cause hypokalemia, which can lead to muscle weakness, tremors, and arrhythmias, as well as ECG changes such as flattened T waves, prolonged PR and QT intervals, and U waves.

      Understanding Parathyroid Hormone and Its Effects

      Parathyroid hormone is a hormone produced by the chief cells of the parathyroid glands. Its main function is to increase the concentration of calcium in the blood by stimulating the PTH receptors in the kidney and bone. This hormone has a short half-life of only 4 minutes.

      The effects of parathyroid hormone are mainly seen in the bone, kidney, and intestine. In the bone, PTH binds to osteoblasts, which then signal to osteoclasts to resorb bone and release calcium. In the kidney, PTH promotes the active reabsorption of calcium and magnesium from the distal convoluted tubule, while decreasing the reabsorption of phosphate. In the intestine, PTH indirectly increases calcium absorption by increasing the activation of vitamin D, which in turn increases calcium absorption.

      Overall, understanding the role of parathyroid hormone is important in maintaining proper calcium levels in the body. Any imbalances in PTH secretion can lead to various disorders such as hyperparathyroidism or hypoparathyroidism.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 5 - What is the crucial step in the production of all steroid hormones? ...

    Incorrect

    • What is the crucial step in the production of all steroid hormones?

      Your Answer: Conversion of cholesterol to prednisolone

      Correct Answer: Conversion of cholesterol to pregnenolone

      Explanation:

      The Role of Pregnenolone in Steroid Hormone Synthesis

      In the production of steroid hormones in the human body, the conversion of cholesterol to pregnenolone is a crucial step. Pregnenolone serves as the precursor for all steroid hormones, and its formation is the limiting factor in the synthesis of these hormones. This conversion process occurs within the mitochondria of steroid-producing tissues. Essentially, the body needs to convert cholesterol to pregnenolone before it can produce any other steroid hormones. This highlights the importance of pregnenolone in the body’s endocrine system and its role in regulating various physiological processes.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 6 - Which of the following explains the mechanism by which PTH increases serum calcium...

    Incorrect

    • Which of the following explains the mechanism by which PTH increases serum calcium levels?

      Your Answer:

      Correct Answer: Activation of vitamin D to increase absorption of calcium from the small intestine.

      Explanation:

      The activity of the 1-α-hydroxylase enzyme, which converts 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol (the active form of vitamin D), is increased by PTH. Osteoblasts mediate the effects of PTH on osteoclasts, as osteoclasts do not have a PTH receptor.

      Understanding Parathyroid Hormone and Its Effects

      Parathyroid hormone is a hormone produced by the chief cells of the parathyroid glands. Its main function is to increase the concentration of calcium in the blood by stimulating the PTH receptors in the kidney and bone. This hormone has a short half-life of only 4 minutes.

      The effects of parathyroid hormone are mainly seen in the bone, kidney, and intestine. In the bone, PTH binds to osteoblasts, which then signal to osteoclasts to resorb bone and release calcium. In the kidney, PTH promotes the active reabsorption of calcium and magnesium from the distal convoluted tubule, while decreasing the reabsorption of phosphate. In the intestine, PTH indirectly increases calcium absorption by increasing the activation of vitamin D, which in turn increases calcium absorption.

      Overall, understanding the role of parathyroid hormone is important in maintaining proper calcium levels in the body. Any imbalances in PTH secretion can lead to various disorders such as hyperparathyroidism or hypoparathyroidism.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 7 - A 35-year-old woman is referred to the endocrine clinic due to missed periods...

    Incorrect

    • A 35-year-old woman is referred to the endocrine clinic due to missed periods and lactation. She has also gained weight and experiences vaginal dryness. The endocrinologist decides to measure her prolactin levels. What hormone is responsible for suppressing the release of prolactin from the pituitary gland?

      Your Answer:

      Correct Answer: Dopamine

      Explanation:

      Dopamine consistently prevents the release of prolactin.

      Understanding Prolactin and Its Functions

      Prolactin is a hormone that is produced by the anterior pituitary gland. Its primary function is to stimulate breast development and milk production in females. During pregnancy, prolactin levels increase to support the growth and development of the mammary glands. It also plays a role in reducing the pulsatility of gonadotropin-releasing hormone (GnRH) at the hypothalamic level, which can block the action of luteinizing hormone (LH) on the ovaries or testes.

      The secretion of prolactin is regulated by dopamine, which constantly inhibits its release. However, certain factors can increase or decrease prolactin secretion. For example, prolactin levels increase during pregnancy, in response to estrogen, and during breastfeeding. Additionally, stress, sleep, and certain drugs like metoclopramide and antipsychotics can also increase prolactin secretion. On the other hand, dopamine and dopaminergic agonists can decrease prolactin secretion.

      Overall, understanding the functions and regulation of prolactin is important for reproductive health and lactation.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 8 - You have been requested to evaluate a patient in your general practice, who...

    Incorrect

    • You have been requested to evaluate a patient in your general practice, who has come in after discovering a new lump in her neck. The patient is in her mid-40s, has no significant medical history, and does not take any regular medications.

      Upon examination, you observe a small mass in the front of the neck that moves upwards when the patient swallows. There is no associated lymphadenopathy. You refer the patient for an ultrasound and biopsy, which reveals the presence of 'Orphan Annie eyes with psammoma bodies.'

      Based on this finding, what is the most probable diagnosis?

      Your Answer:

      Correct Answer: Papillary thyroid cancer

      Explanation:

      The patient has a painless lump in the thyroid gland that moves on swallowing, indicating thyroid pathology. The biopsy result of Orphan Annie eyes with psammoma bodies is a characteristic finding in papillary thyroid cancer, which is a slow-growing malignancy with less likelihood of lymphadenopathy. Graves’ disease is an incorrect diagnosis as it would not present with this appearance on biopsy and would likely exhibit signs of thyrotoxicosis. A multinodular goitre also does not have this appearance and may cause a thyrotoxic state. Anaplastic carcinoma is a more aggressive thyroid malignancy that readily invades nearby tissues and has a different histological appearance with spindle cells and giant cells.

      Thyroid cancer rarely causes hyperthyroidism or hypothyroidism as it does not usually secrete thyroid hormones. The most common type of thyroid cancer is papillary carcinoma, which is often found in young females and has an excellent prognosis. Follicular carcinoma is less common, while medullary carcinoma is a cancer of the parafollicular cells that secrete calcitonin and is associated with multiple endocrine neoplasia type 2. Anaplastic carcinoma is rare and not responsive to treatment, causing pressure symptoms. Lymphoma is also rare and associated with Hashimoto’s thyroiditis.

      Management of papillary and follicular cancer involves a total thyroidectomy followed by radioiodine to kill residual cells. Yearly thyroglobulin levels are monitored to detect early recurrent disease. Papillary carcinoma usually contains a mixture of papillary and colloidal filled follicles, while follicular adenoma presents as a solitary thyroid nodule and malignancy can only be excluded on formal histological assessment. Follicular carcinoma may appear macroscopically encapsulated, but microscopically capsular invasion is seen. Medullary carcinoma is associated with raised serum calcitonin levels and familial genetic disease in up to 20% of cases. Anaplastic carcinoma is most common in elderly females and is treated by resection where possible, with palliation achieved through isthmusectomy and radiotherapy. Chemotherapy is ineffective.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 9 - The medical team at a pediatric unit faces difficulty in determining the sex...

    Incorrect

    • The medical team at a pediatric unit faces difficulty in determining the sex of a newborn baby as the external genitalia appear ambiguous. The suspected condition is linked to an excess of androgen and a deficiency of mineralocorticoid. Can you explain the underlying pathophysiology?

      Your Answer:

      Correct Answer: Deficiency of 21-alphahydroxylase

      Explanation:

      The clinical scenario described in the question is indicative of congenital adrenal hyperplasia, which is caused by a deficiency of the enzyme 21-alphahydroxylase. This leads to an increase in androgen production, resulting in virilization of genitalia in XX females, making them appear as males at birth.

      On the other hand, a deficiency of 5-alpha reductase causes the opposite situation, where genetically XY males have external female genitalia.

      Type 1 diabetes mellitus may be associated with the presence of autoantibodies against glutamic acid decarboxylase.

      A defect in the AIRE gene can lead to APECED, which is characterized by hypoparathyroidism, adrenal failure, and candidiasis.

      Similarly, a defect in the FOXP3 gene can cause IPEX, which presents with immune dysregulation, polyendocrinopathy, and enteropathy.

      Congenital adrenal hyperplasia is a genetic condition that affects the adrenal glands and can result in various symptoms depending on the specific enzyme deficiency. One common form is 21-hydroxylase deficiency, which can cause virilization of female genitalia, precocious puberty in males, and a salt-losing crisis in 60-70% of patients during the first few weeks of life. Another form is 11-beta hydroxylase deficiency, which can also cause virilization and precocious puberty, as well as hypertension and hypokalemia. A third form is 17-hydroxylase deficiency, which typically does not cause virilization in females but can result in intersex characteristics in boys and hypertension.

      Overall, congenital adrenal hyperplasia can have significant impacts on a person’s physical development and health, and early diagnosis and treatment are important for managing symptoms and preventing complications.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 10 - A 42-year-old woman visits her GP complaining of chest pain. She has a...

    Incorrect

    • A 42-year-old woman visits her GP complaining of chest pain. She has a history of hypertension and is currently taking metformin for diabetes. The GP observes that her BMI is 45. What is a possible complication of the metabolic syndrome in this case?

      Your Answer:

      Correct Answer: Ischemic stroke

      Explanation:

      Metabolic syndrome is a group of risk factors for cardiovascular disease that are caused by insulin resistance and central obesity.

      Obesity is associated with higher rates of illness and death, as well as decreased productivity and functioning, increased healthcare expenses, and social and economic discrimination.

      The consequences of obesity include strokes, type 2 diabetes, heart disease, certain cancers (such as breast, colon, and endometrial), polycystic ovarian syndrome, obstructive sleep apnea, fatty liver, gallstones, and mental health issues.

      The Physiology of Obesity: Leptin and Ghrelin

      Leptin is a hormone produced by adipose tissue that plays a crucial role in regulating body weight. It acts on the hypothalamus, specifically on the satiety centers, to decrease appetite and induce feelings of fullness. In cases of obesity, where there is an excess of adipose tissue, leptin levels are high. Leptin also stimulates the release of melanocyte-stimulating hormone (MSH) and corticotrophin-releasing hormone (CRH), which further contribute to the regulation of appetite. On the other hand, low levels of leptin stimulate the release of neuropeptide Y (NPY), which increases appetite.

      Ghrelin, on the other hand, is a hormone that stimulates hunger. It is mainly produced by the P/D1 cells lining the fundus of the stomach and epsilon cells of the pancreas. Ghrelin levels increase before meals, signaling the body to prepare for food intake, and decrease after meals, indicating that the body has received enough nutrients.

      In summary, the balance between leptin and ghrelin plays a crucial role in regulating appetite and body weight. In cases of obesity, there is an imbalance in this system, with high levels of leptin and potentially disrupted ghrelin signaling, leading to increased appetite and weight gain.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 11 - A 53-year-old male presents to an endocrinology clinic with recurring symptoms of painful...

    Incorrect

    • A 53-year-old male presents to an endocrinology clinic with recurring symptoms of painful fingers and hands that seem to be enlarging. He was previously diagnosed with acromegaly eight months ago and underwent transsphenoidal surgery six months ago to remove the pituitary adenoma responsible. During examination, his facial features appear rough, and his hands are large and spade-like. You opt to manage this patient's symptoms with medication and initiate a trial of octreotide.

      What physiological function is linked to this medication?

      Your Answer:

      Correct Answer: Inhibition of glucagon secretion from the pancreas

      Explanation:

      Somatostatin analogues, such as octreotide, are used to treat acromegaly in patients who have not responded well to surgery. Somatostatin is a hormone that has various functions, including inhibiting the secretion of growth hormone from the anterior pituitary gland and insulin and glucagon from the pancreas. Therefore, the correct answer is that somatostatin inhibits the secretion of glucagon.

      The secretion of ACTH by the pancreas is regulated by a negative feedback loop involving cortisol and corticotropin-releasing hormone (CRH). When blood cortisol levels decrease, CRH is secreted from the hypothalamus, which then stimulates the secretion of ACTH from the anterior pituitary gland.

      Somatostatin analogues typically do not affect the secretion of aldosterone from the pancreas, which is primarily stimulated by angiotensin-II.

      Somatostatin analogues inhibit the secretion of growth hormone from the anterior pituitary gland. The hormone responsible for stimulating the secretion of growth hormone is growth hormone-releasing hormone (GHRH).

      The secretion of insulin by pancreatic β-cells is inhibited by somatostatin analogues. The primary stimulus for insulin secretion is low blood glucose levels, but other substances such as arginine and leucine, acetylcholine, sulfonylurea, cholecystokinin, and incretins can also stimulate insulin release.

      Somatostatin: The Inhibitor Hormone

      Somatostatin, also known as growth hormone inhibiting hormone (GHIH), is a hormone produced by delta cells found in the pancreas, pylorus, and duodenum. Its main function is to inhibit the secretion of growth hormone, insulin, and glucagon. It also decreases acid and pepsin secretion, as well as pancreatic enzyme secretion. Additionally, somatostatin inhibits the trophic effects of gastrin and stimulates gastric mucous production.

      Somatostatin analogs are commonly used in the management of acromegaly, a condition characterized by excessive growth hormone secretion. These analogs work by inhibiting growth hormone secretion, thereby reducing the symptoms associated with acromegaly.

      The secretion of somatostatin is regulated by various factors. Its secretion increases in response to fat, bile salts, and glucose in the intestinal lumen, as well as glucagon. On the other hand, insulin decreases the secretion of somatostatin.

      In summary, somatostatin plays a crucial role in regulating the secretion of various hormones and enzymes in the body. Its inhibitory effects on growth hormone, insulin, and glucagon make it an important hormone in the management of certain medical conditions.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 12 - A 20-year-old man comes to the emergency department complaining of abdominal pain, vomiting,...

    Incorrect

    • A 20-year-old man comes to the emergency department complaining of abdominal pain, vomiting, polyuria, polydipsia, and confusion that have been present for the past 12 hours. During the examination, he shows mild generalized abdominal tenderness without guarding. His breathing is observed to be deep and rapid.

      The patient has a medical history of type 1 diabetes, but he confesses to being non-compliant with his insulin regimen.

      What is the probable pathophysiology behind his symptoms?

      Your Answer:

      Correct Answer: Uncontrolled lipolysis which results in an excess of free fatty acids

      Explanation:

      The cause of DKA is uncontrolled lipolysis, leading to an excess of free fatty acids that are converted to ketone bodies. This results in high levels of ketones in the urine. Hypoglycemia activates the sympathetic nervous system. Lactic acidosis is similar to DKA but lacks the presence of ketones in urine. Appendicitis can cause abdominal pain, vomiting, and urinary symptoms, but the presence of ketones in urine suggests DKA. Urinary tract infections are rare in men under 50 and typically occur with abnormal anatomy or catheterization.

      Diabetic ketoacidosis (DKA) is a serious complication of type 1 diabetes mellitus, accounting for around 6% of cases. It can also occur in rare cases of extreme stress in patients with type 2 diabetes mellitus. DKA is caused by uncontrolled lipolysis, resulting in an excess of free fatty acids that are converted to ketone bodies. The most common precipitating factors of DKA are infection, missed insulin doses, and myocardial infarction. Symptoms include abdominal pain, polyuria, polydipsia, dehydration, Kussmaul respiration, and breath that smells like acetone. Diagnostic criteria include glucose levels above 11 mmol/l or known diabetes mellitus, pH below 7.3, bicarbonate below 15 mmol/l, and ketones above 3 mmol/l or urine ketones ++ on dipstick.

      Management of DKA involves fluid replacement, insulin, and correction of electrolyte disturbance. Fluid replacement is necessary as most patients with DKA are deplete around 5-8 litres. Isotonic saline is used initially, even if the patient is severely acidotic. Insulin is administered through an intravenous infusion, and correction of electrolyte disturbance is necessary. Long-acting insulin should be continued, while short-acting insulin should be stopped. Complications may occur from DKA itself or the treatment, such as gastric stasis, thromboembolism, arrhythmias, acute respiratory distress syndrome, acute kidney injury, and cerebral edema. Children and young adults are particularly vulnerable to cerebral edema following fluid resuscitation in DKA and often need 1:1 nursing to monitor neuro-observations, headache, irritability, visual disturbance, focal neurology, etc.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 13 - A 55-year-old man with a smoking history of over 30 years presented to...

    Incorrect

    • A 55-year-old man with a smoking history of over 30 years presented to the emergency department with acute confusion and disorientation. He was unable to recognize his family members and relatives. He had been experiencing unexplained weight loss, loss of appetite, and occasional episodes of haemoptysis for the past few months. Urgent blood tests were performed, revealing abnormal levels of electrolytes and renal function.

      Based on the likely diagnosis, what is the mechanism of action of the hormone that is being secreted excessively in this case?

      Your Answer:

      Correct Answer: Insertion of aquaporin-2 channels

      Explanation:

      Antidiuretic hormone (ADH) plays a crucial role in promoting water reabsorption by inserting aquaporin-2 channels in principal cells. In small-cell lung cancer patients, decreased serum sodium levels are commonly caused by the paraneoplastic syndrome of inadequate ADH secretion (SIADH) or ADH released during the initial lysis of tumour cells after chemotherapy. It is important to note that arteriolar vasodilation, promoting water excretion, decreased urine osmolarity, and increased portal blood flow are not functions of ADH.

      Understanding Antidiuretic Hormone (ADH)

      Antidiuretic hormone (ADH) is a hormone that is produced in the supraoptic nuclei of the hypothalamus and released by the posterior pituitary gland. Its primary function is to conserve body water by promoting water reabsorption in the collecting ducts of the kidneys through the insertion of aquaporin-2 channels.

      ADH secretion is regulated by various factors. An increase in extracellular fluid osmolality, a decrease in volume or pressure, and the presence of angiotensin II can all increase ADH secretion. Conversely, a decrease in extracellular fluid osmolality, an increase in volume, a decrease in temperature, or the absence of ADH can decrease its secretion.

      Diabetes insipidus (DI) is a condition that occurs when there is either a deficiency of ADH (cranial DI) or an insensitivity to ADH (nephrogenic DI). Cranial DI can be treated with desmopressin, which is an analog of ADH.

      Overall, understanding the role of ADH in regulating water balance in the body is crucial for maintaining proper hydration and preventing conditions like DI.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 14 - A 57-year-old man with a history of type 2 diabetes visits his GP...

    Incorrect

    • A 57-year-old man with a history of type 2 diabetes visits his GP for a check-up and is prescribed a new medication, a glucagon-like peptide (GLP-1) analogue. Where is this hormone typically secreted from in the body?

      Your Answer:

      Correct Answer: Ileum

      Explanation:

      When comparing the effects of oral glucose and IV glucose on insulin release, it was found that oral glucose resulted in a higher insulin release. This suggests that the response of the gut plays a role in insulin release. Incretins are a group of hormones produced in the gastrointestinal tract that stimulate insulin release from β-cells, even before blood glucose levels become elevated.

      There are two main types of incretins: gastric inhibitory peptide (GIP), which is released from the duodenum and is glucose-dependent, and glucagon-like peptide (GLP-1), which is produced in the distal ileum.

      The glucagon gene is processed differently in the brain and intestines than in the pancreas. In the brain and intestines, GLP1&2 are released, which function as appetite suppressants. In the pancreas, they increase insulin release and β-cell proliferation.

      Diabetes mellitus is a condition that has seen the development of several drugs in recent years. One hormone that has been the focus of much research is glucagon-like peptide-1 (GLP-1), which is released by the small intestine in response to an oral glucose load. In type 2 diabetes mellitus (T2DM), insulin resistance and insufficient B-cell compensation occur, and the incretin effect, which is largely mediated by GLP-1, is decreased. GLP-1 mimetics, such as exenatide and liraglutide, increase insulin secretion and inhibit glucagon secretion, resulting in weight loss, unlike other medications. They are sometimes used in combination with insulin in T2DM to minimize weight gain. Dipeptidyl peptidase-4 (DPP-4) inhibitors, such as vildagliptin and sitagliptin, increase levels of incretins by decreasing their peripheral breakdown, are taken orally, and do not cause weight gain. Nausea and vomiting are the major adverse effects of GLP-1 mimetics, and the Medicines and Healthcare products Regulatory Agency has issued specific warnings on the use of exenatide, reporting that it has been linked to severe pancreatitis in some patients. NICE guidelines suggest that a DPP-4 inhibitor might be preferable to a thiazolidinedione if further weight gain would cause significant problems, a thiazolidinedione is contraindicated, or the person has had a poor response to a thiazolidinedione.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 15 - A 14-year-old boy is brought to the clinic by his mother due to...

    Incorrect

    • A 14-year-old boy is brought to the clinic by his mother due to concerns about his height compared to other boys his age. The boy also shares that he often receives comments about his appearance, with some likening him to a toy doll. What can be inferred about the pattern of hormone release that he may be lacking?

      Your Answer:

      Correct Answer: It is released in a pulsatile manner

      Explanation:

      The doll-like appearance of the boy in his presentation suggests that he may be suffering from growth hormone deficiency, which can cause short stature, forehead prominence, and maxillary hypoplasia. The hypothalamus controls the release of growth hormone through the pulsatile release of growth hormone releasing hormone. Therefore, measuring GHRH levels is not a useful method for investigating growth hormone deficiency.

      Understanding Growth Hormone and Its Functions

      Growth hormone (GH) is a hormone produced by the somatotroph cells in the anterior pituitary gland. It plays a crucial role in postnatal growth and development, as well as in regulating protein, lipid, and carbohydrate metabolism. GH acts on a transmembrane receptor for growth factor, leading to receptor dimerization and direct or indirect effects on tissues via insulin-like growth factor 1 (IGF-1), which is primarily secreted by the liver.

      GH secretion is regulated by various factors, including growth hormone releasing hormone (GHRH), fasting, exercise, and sleep. Conversely, glucose and somatostatin can decrease GH secretion. Disorders associated with GH include acromegaly, which results from excess GH, and GH deficiency, which can lead to short stature.

      In summary, GH is a vital hormone that plays a significant role in growth and metabolism. Understanding its functions and regulation can help in the diagnosis and treatment of GH-related disorders.

    • This question is part of the following fields:

      • Endocrine System
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  • Question 16 - A 60-year-old patient visits their doctor complaining of dehydration caused by vomiting and...

    Incorrect

    • A 60-year-old patient visits their doctor complaining of dehydration caused by vomiting and diarrhoea. The kidneys detect reduced renal perfusion, leading to activation of the renin-angiotensin-aldosterone system. What is the specific part of the adrenal gland required for this system?

      Your Answer:

      Correct Answer: Zona glomerulosa

      Explanation:

      Aldosterone is produced in the zona glomerulosa of the adrenal gland.

      Renin is released by juxtaglomerular cells located in the nephron.

      ACE is produced by the pulmonary endothelium in the lungs.

      The adrenal gland is composed of the zona glomerulosa, fasciculata, and reticularis.

      Glucocorticoids are produced in the zona fasciculata.

      Adrenal Physiology: Medulla and Cortex

      The adrenal gland is composed of two main parts: the medulla and the cortex. The medulla is responsible for secreting the catecholamines noradrenaline and adrenaline, which are released in response to sympathetic nervous system stimulation. The chromaffin cells of the medulla are innervated by the splanchnic nerves, and the release of these hormones is triggered by the secretion of acetylcholine from preganglionic sympathetic fibers. Phaeochromocytomas, which are tumors derived from chromaffin cells, can cause excessive secretion of both adrenaline and noradrenaline.

      The adrenal cortex is divided into three distinct zones: the zona glomerulosa, zona fasciculata, and zona reticularis. Each zone is responsible for secreting different hormones. The outer zone, zona glomerulosa, secretes aldosterone, which regulates electrolyte balance and blood pressure. The middle zone, zona fasciculata, secretes glucocorticoids, which are involved in the regulation of metabolism, immune function, and stress response. The inner zone, zona reticularis, secretes androgens, which are involved in the development and maintenance of male sex characteristics.

      Most of the hormones secreted by the adrenal cortex, including glucocorticoids and aldosterone, are bound to plasma proteins in the circulation. Glucocorticoids are inactivated and excreted by the liver. Understanding the physiology of the adrenal gland is important for the diagnosis and treatment of various endocrine disorders.

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      • Endocrine System
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  • Question 17 - Sarah is a 15-year-old female who presented to the clinic with concerns about...

    Incorrect

    • Sarah is a 15-year-old female who presented to the clinic with concerns about her development. She has not grown as expected and remains shorter than most of the girls in her class. She also notes that she has not started her period yet, which is affecting her confidence.

      On examination, she is 150cm tall and has no breast development. Pubic hair is sparse and axillary hair is absent. The uterus and ovaries are not palpable. A cleft palate is noted on examination of the mouth. When cranial nerve I was examined, she was unable to detect the smell of the odours sampled.

      Blood tests show low levels of estrogen, follicular stimulating hormone (FSH) and luteinizing hormone (LH). Liver function tests were normal. Blood glucose reading was 5.6mmol/L. Iron studies were unremarkable.

      What is the likely cause for her symptoms?

      Your Answer:

      Correct Answer: Kallmann syndrome

      Explanation:

      The patient’s symptoms of delayed puberty and underdeveloped secondary sexual characteristics, along with a cleft palate and anosmia, suggest Kallmann syndrome. This condition is characterized by hypogonadotropic hypogonadism, as evidenced by low-normal levels of LH and FSH, as well as low testosterone levels. Kallmann syndrome is an X-linked inherited disorder caused by the failure of gonadotrophin-releasing hormone-producing neurons to migrate properly during fetal development.

      While Klinefelter syndrome can also cause delayed puberty and small testes, it is associated with hypergonadotropic hypogonadism, which is characterized by elevated levels of FSH and LH but low testosterone levels. Anosmia is not typically a symptom of Klinefelter syndrome.

      Hemochromatosis, a condition in which iron accumulates in the body, can also cause hypogonadotropic hypogonadism by affecting the hypothalamus. However, this is unlikely in this case as the patient’s iron studies were normal and anosmia is not a common symptom of hemochromatosis.

      Kallmann’s syndrome is a condition that can cause delayed puberty due to hypogonadotropic hypogonadism. It is often inherited as an X-linked recessive trait and is believed to be caused by a failure of GnRH-secreting neurons to migrate to the hypothalamus. One of the key indicators of Kallmann’s syndrome is anosmia, or a lack of smell, in boys with delayed puberty. Other features may include hypogonadism, cryptorchidism, low sex hormone levels, and normal or above-average height. Some patients may also have cleft lip/palate and visual/hearing defects.

      Management of Kallmann’s syndrome typically involves testosterone supplementation. Gonadotrophin supplementation may also be used to stimulate sperm production if fertility is desired later in life. It is important for individuals with Kallmann’s syndrome to receive appropriate medical care and monitoring to manage their symptoms and ensure optimal health outcomes.

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      • Endocrine System
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  • Question 18 - A 36-year-old male visits the GP after being diagnosed with Conn's syndrome, which...

    Incorrect

    • A 36-year-old male visits the GP after being diagnosed with Conn's syndrome, which causes excessive production of aldosterone. How will this affect the balance of sodium and potassium in his blood?

      Your Answer:

      Correct Answer: Increased sodium, decreased potassium

      Explanation:

      Hypertension, hypernatraemia, and hypokalemia are common symptoms of primary hyperaldosteronism.

      The adrenal gland produces aldosterone, which is responsible for regulating potassium levels. Its primary function is to increase sodium absorption and decrease potassium secretion in the distal tubules and collecting duct of the nephron. As a result, sodium levels increase while potassium levels decrease.

      Primary hyperaldosteronism is a condition characterized by hypertension, hypokalaemia, and alkalosis. It was previously believed that adrenal adenoma, also known as Conn’s syndrome, was the most common cause of this condition. However, recent studies have shown that bilateral idiopathic adrenal hyperplasia is responsible for up to 70% of cases. It is important to differentiate between the two causes as it determines the appropriate treatment. Adrenal carcinoma is an extremely rare cause of primary hyperaldosteronism.

      To diagnose primary hyperaldosteronism, the 2016 Endocrine Society recommends a plasma aldosterone/renin ratio as the first-line investigation. This test should show high aldosterone levels alongside low renin levels due to negative feedback from sodium retention caused by aldosterone. If the results are positive, a high-resolution CT abdomen and adrenal vein sampling are used to differentiate between unilateral and bilateral sources of aldosterone excess. If the CT is normal, adrenal venous sampling (AVS) can be used to distinguish between unilateral adenoma and bilateral hyperplasia.

      The management of primary hyperaldosteronism depends on the underlying cause. Adrenal adenoma is treated with surgery, while bilateral adrenocortical hyperplasia is managed with an aldosterone antagonist such as spironolactone. It is important to accurately diagnose and manage primary hyperaldosteronism to prevent complications such as cardiovascular disease and stroke.

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      • Endocrine System
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  • Question 19 - A 50-year-old man has a laparotomy and repair of incisional hernia. Which hormone...

    Incorrect

    • A 50-year-old man has a laparotomy and repair of incisional hernia. Which hormone is most unlikely to be released in higher amounts after the surgery?

      Your Answer:

      Correct Answer: Insulin

      Explanation:

      Reduced secretion of insulin and thyroxine is common after surgery, which can make it challenging to manage diabetes in people with insulin resistance due to the additional release of glucocorticoids.

      Surgery triggers a stress response that causes hormonal and metabolic changes in the body. This response is characterized by substrate mobilization, muscle protein loss, sodium and water retention, suppression of anabolic hormone secretion, activation of the sympathetic nervous system, and immunological and haematological changes. The hypothalamic-pituitary axis and the sympathetic nervous systems are activated, and the normal feedback mechanisms of control of hormone secretion fail. The stress response is associated with increased growth hormone, cortisol, renin, adrenocorticotrophic hormone (ACTH), aldosterone, prolactin, antidiuretic hormone, and glucagon, while insulin, testosterone, oestrogen, thyroid stimulating hormone, luteinizing hormone, and follicle stimulating hormone are decreased or remain unchanged. The metabolic effects of cortisol are enhanced, including skeletal muscle protein breakdown, stimulation of lipolysis, anti-insulin effect, mineralocorticoid effects, and anti-inflammatory effects. The stress response also affects carbohydrate, protein, lipid, salt and water metabolism, and cytokine release. Modifying the response can be achieved through opioids, spinal anaesthesia, nutrition, growth hormone, anabolic steroids, and normothermia.

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  • Question 20 - A 56-year-old woman visits her primary care physician with concerns about recent weight...

    Incorrect

    • A 56-year-old woman visits her primary care physician with concerns about recent weight gain. She reports maintaining her usual diet and exercise routine, but has noticed her face appearing rounder and the development of purplish stretch marks on her abdomen. During the exam, her heart rate is 89 beats per minute, respiratory rate is 16 breaths per minute, and blood pressure is 157/84 mmHg. Her waist circumference measures 41 inches and her body mass index is 28 kg/m2. What is one effect of the primary hormone involved in this patient's condition?

      Your Answer:

      Correct Answer: Upregulation of alpha-1-adrenoceptors on arterioles

      Explanation:

      The patient is exhibiting symptoms consistent with a state of elevated cortisol levels, known as Cushing syndrome. These symptoms include recent weight gain, a round face (moon face), abdominal striae, high blood pressure, and truncal obesity. Cushing syndrome can have various causes, including the use of glucocorticoids or an ectopic ACTH secretion.

      Elevated cortisol levels can lead to an increase in blood glucose levels, putting individuals at risk for hyperglycemia and diabetes. Cortisol can also suppress the immune system, inhibiting the production of prostaglandins, leukotrienes, and interleukin-2, and decreasing the adhesion of white blood cells. Additionally, cortisol can up-regulate alpha-1-adrenoceptors on arterioles, resulting in high blood pressure. High cortisol levels can also decrease osteoblast activity, leading to weakened bones, and reduce fibroblast activity and collagen synthesis, resulting in delayed wound healing. The abdominal striae seen in patients with high cortisol levels are typically due to decreased collagen synthesis.

      Causes of Cushing’s Syndrome

      Cushing’s syndrome is a condition that can be caused by both endogenous and exogenous factors. However, it is important to note that exogenous causes, such as the use of glucocorticoid therapy, are more common than endogenous ones. The condition can be classified into two categories: ACTH dependent and ACTH independent causes.

      ACTH dependent causes of Cushing’s syndrome include Cushing’s disease, which is caused by a pituitary tumor secreting ACTH and producing adrenal hyperplasia. Ectopic ACTH production, which is caused by small cell lung cancer, is another ACTH dependent cause. On the other hand, ACTH independent causes include iatrogenic factors such as steroid use, adrenal adenoma, adrenal carcinoma, Carney complex, and micronodular adrenal dysplasia.

      In some cases, a condition called Pseudo-Cushing’s can mimic Cushing’s syndrome. This is often caused by alcohol excess or severe depression and can cause false positive results in dexamethasone suppression tests or 24-hour urinary free cortisol tests. To differentiate between Cushing’s syndrome and Pseudo-Cushing’s, an insulin stress test may be used.

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      • Endocrine System
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