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Question 1
Correct
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A 23-year-old male visits his GP complaining of polyuria, chronic thirst and pale-coloured urine that have persisted for 3 months. He had a concussion from a car accident a month before the onset of his urinary symptoms. The patient is diagnosed with cranial diabetes insipidus after undergoing several tests.
What would the water deprivation test likely reveal in this case?Your Answer: Low urine osmolality after fluid deprivation, but high after desmopressin
Explanation:The correct answer is low urine osmolality after fluid deprivation, but high after desmopressin, for a patient with cranial diabetes insipidus (DI). This condition is characterized by polyuria, chronic thirst, and pale-coloured urine, and is caused by insufficient antidiuretic hormone (ADH) secretion. As a result, the kidneys are unable to concentrate urine, leading to a low urine osmolality even during water deprivation. However, the kidneys will respond to desmopressin (synthetic ADH) to produce concentrated urine.
High urine osmolality after both fluid deprivation and desmopressin is incorrect, as it would be seen in a healthy individual or a patient with primary polydipsia, a psychogenic disorder characterized by excessive drinking despite being properly hydrated.
Low urine osmolality after both fluid deprivation and desmopressin is incorrect, as this is typical of nephrogenic DI, a condition in which the kidneys are insensitive to ADH.
High urine osmolality after fluid deprivation, but normal after desmopressin is incorrect, as this would not be commonly seen with any pathological state.
Low urine osmolality after desmopressin, but high after fluid deprivation is incorrect, as this would not be commonly seen with any pathological state.
The water deprivation test is a diagnostic tool used to assess patients with polydipsia, or excessive thirst. During the test, the patient is instructed to refrain from drinking water, and their bladder is emptied. Hourly measurements of urine and plasma osmolalities are taken to monitor changes in the body’s fluid balance. The results of the test can help identify the underlying cause of the patient’s polydipsia. Normal results show a high urine osmolality after the administration of DDAVP, while psychogenic polydipsia is characterized by a low urine osmolality. Cranial DI and nephrogenic DI are both associated with high plasma osmolalities and low urine osmolalities.
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This question is part of the following fields:
- Endocrine System
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Question 2
Correct
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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: 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.
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This question is part of the following fields:
- Endocrine System
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Question 3
Incorrect
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Which of the following most accurately explains how glucocorticoids work?
Your Answer: Activation of transmembrane tyrosine kinase systems to affect intranuclear gene transcription
Correct Answer: Binding of intracellular receptors that migrate to the nucleus to then affect gene transcription
Explanation:The effects of glucocorticoids are mediated by intracellular receptors that bind to them and are subsequently transported to the nucleus, where they modulate gene transcription.
Corticosteroids are commonly prescribed medications that can be taken orally or intravenously, or applied topically. They mimic the effects of natural steroids in the body and can be used to replace or supplement them. However, the use of corticosteroids is limited by their numerous side effects, which are more common with prolonged and systemic use. These side effects can affect various systems in the body, including the endocrine, musculoskeletal, gastrointestinal, ophthalmic, and psychiatric systems. Some of the most common side effects include impaired glucose regulation, weight gain, osteoporosis, and increased susceptibility to infections. Patients on long-term corticosteroids should have their doses adjusted during intercurrent illness, and the medication should not be abruptly withdrawn to avoid an Addisonian crisis. Gradual withdrawal is recommended for patients who have received high doses or prolonged treatment.
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This question is part of the following fields:
- Endocrine System
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Question 4
Correct
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A 23-year-old male patient visits his GP complaining of breast tissue enlargement that has been progressively worsening for the past 3 months. He also reports the presence of a new lump on his left testicle. Upon thorough examination and taking a detailed medical history, the GP suspects that the patient may be suffering from testicular cancer.
What is the probable diagnosis?Your Answer: HCG secreting seminoma
Explanation:Gynaecomastia can be caused by testicular conditions such as seminoma that secrete hCG.
Understanding Gynaecomastia: Causes and Drug Triggers
Gynaecomastia is a condition characterized by the abnormal growth of breast tissue in males, often caused by an increased ratio of oestrogen to androgen. It is important to distinguish the causes of gynaecomastia from those of galactorrhoea, which is caused by the actions of prolactin on breast tissue.
Physiological changes during puberty can lead to gynaecomastia, but it can also be caused by syndromes with androgen deficiency such as Kallmann and Klinefelter’s, testicular failure due to mumps, liver disease, testicular cancer, and hyperthyroidism. Additionally, haemodialysis and ectopic tumour secretion can also trigger gynaecomastia.
Drug-induced gynaecomastia is also a common cause, with spironolactone being the most frequent trigger. Other drugs that can cause gynaecomastia include cimetidine, digoxin, cannabis, finasteride, GnRH agonists like goserelin and buserelin, oestrogens, and anabolic steroids. However, it is important to note that very rare drug causes of gynaecomastia include tricyclics, isoniazid, calcium channel blockers, heroin, busulfan, and methyldopa.
In summary, understanding the causes and drug triggers of gynaecomastia is crucial in diagnosing and treating this condition.
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This question is part of the following fields:
- Endocrine System
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Question 5
Incorrect
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A man in his early 50s comes to the hospital with a fever and cough. An X-ray shows pneumonia in his left lower lobe. Upon arrival at the emergency department, his blood pressure is 83/60mmHg and his heart rate is 112/min. The doctor prescribes antibiotics and IV fluids.
What is the primary way the body reacts to a drop in blood pressure?Your Answer: Decreased heart rate and vasoconstriction
Correct Answer: Insertion of AQP-2 channels in collecting ducts
Explanation:When blood pressure drops, the body initiates several physiological responses, one of which is the activation of the renin-angiotensin aldosterone system (RAAS). This system breaks down bradykinin, a potent vasodilator, through the action of angiotensin-converting enzyme (ACE).
RAAS activation results in increased aldosterone levels, which in turn increases the number of epithelial sodium channels (ENAC) to enhance sodium reabsorption.
Another response to low blood pressure is the release of antidiuretic hormone, which promotes the insertion of aquaporin-2 channels in the collecting duct. This mechanism increases water reabsorption to help maintain fluid balance in the body.
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.
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This question is part of the following fields:
- Endocrine System
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Question 6
Incorrect
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A 45-year-old male has presented to discuss the management of primary hyperparathyroidism. He was diagnosed 3 weeks ago after complaining of bone pain and gastrointestinal discomfort. Today's blood results indicate an electrolyte abnormality.
What is the most probable electrolyte abnormality that will be observed on the blood results?Your Answer: Hypocalcaemia
Correct Answer: Hypophosphataemia
Explanation:Renal phosphate reabsorption is decreased by PTH.
When PTH levels are excessive, as seen in hyperparathyroidism, renal reabsorption is reduced, leading to low serum phosphate levels. PTH inhibits osteoblasts, not osteoclasts, resulting in an increase in plasma calcium levels. PTH is released in response to low calcium levels and works to increase calcium resorption in the kidneys. Additionally, PTH increases magnesium resorption in the kidneys.
It is important to note that PTH does not affect potassium levels.
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.
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This question is part of the following fields:
- Endocrine System
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Question 7
Correct
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A 15-year-old male arrives at the emergency department with complaints of abdominal pain, nausea, and shortness of breath. He has a history of insulin-dependent diabetes and is diagnosed with diabetic ketoacidosis after undergoing tests. During treatment, which electrolyte should you be particularly cautious of, as it may become depleted in the body despite appearing normal in plasma concentrations?
Your Answer: Potassium
Explanation:Insulin normally helps to move potassium into cells, but in a state of ketoacidosis, there is a lack of insulin to perform this function. As a result, potassium leaks out of cells. Additionally, high levels of glucose in the blood lead to glycosuria in the urine, causing potassium loss through the kidneys.
Even though patients in a ketoacidotic state may have normal levels of potassium in their blood, their overall potassium levels in the body are often depleted. When insulin is administered to these patients, it can cause a dangerous drop in potassium levels as the minimal amount of potassium left in the body is driven into cells.
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.
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This question is part of the following fields:
- Endocrine System
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Question 8
Correct
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A 50-year-old woman has just had a thyroidectomy to treat medullary thyroid cancer. What is the clinical tumor marker used to screen for recurrence?
Your Answer: Calcitonin
Explanation:Calcitonin is used in clinical practice to detect recurrence of medullary thyroid cancer. Thyroid function tests are not used for diagnosis or follow-up of malignancies. However, regular monitoring of TSH levels may be necessary for patients taking thyroxine.
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 colloid 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.
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This question is part of the following fields:
- Endocrine System
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Question 9
Incorrect
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A 30-year-old female with a two year history of type 1 diabetes presents with a two day history of colicky abdominal pain and vomiting. She has been relatively anorexic and has cut down on her insulin today as she has not been able to eat that much.
On examination she has a sweet smell to her breath, has some loss of skin turgor, has a pulse of 102 bpm regular and a blood pressure of 112/70 mmHg. Her abdomen is generally soft with some epigastric tenderness.
BM stix analysis reveals a glucose of 19 mmol/L (3.0-6.0).
What investigation would be the most important for this woman?Your Answer: Plasma glucose concentration
Correct Answer: Blood gas analysis
Explanation:Diabetic Ketoacidosis: Diagnosis and Investigations
Diabetic ketoacidosis (DKA) is a serious complication of diabetes that can lead to life-threatening consequences. Symptoms include ketotic breath, vomiting, abdominal pain, and dehydration. To confirm the diagnosis, it is essential to prove the presence of acidosis and ketosis. The most urgent and important investigation is arterial or venous blood gas analysis, which can reveal the level of acidosis and low bicarbonate.
Other investigations that can be helpful include a full blood count (FBC) to show haemoconcentration and a raised white cell count, and urinalysis to detect glucose and ketones. However, venous or capillary ketones are needed to confirm DKA. A plasma glucose test is also part of the investigation, but it is not as urgent as the blood gas analysis.
An abdominal x-ray is not useful in diagnosing DKA, and a chest x-ray is only indicated if there are signs of a lower respiratory tract infection. Blood cultures are unlikely to grow anything, and amylase levels are often raised but do not provide diagnostic information in this case.
It is important to note that DKA can occur even if the plasma glucose level is normal. Therefore, prompt diagnosis and treatment are crucial to prevent complications and improve outcomes.
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This question is part of the following fields:
- Endocrine System
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Question 10
Correct
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Sam, a 75-year-old man, presents to the GP with a complaint of breast growth that has developed rapidly over the past 3 months. Sam insists that he has no trouble with sexual function. He has recently been diagnosed with a heart problem and is taking multiple medications for it, although he cannot recall their names. Other than that, he claims to be in good health. Upon examination, all of Sam's vital signs are within normal limits. After measuring his height and weight, his body mass index is calculated to be 24 kg/m². Each breast is approximately 10 cm in diameter, with large nipples and tenderness but no pain. Moderate cardiomegaly and a 3rd heart sound are noted during chest assessment. No abnormalities are found during an abdominal examination. Pitting edema is present up to his mid calf. Based on the history and examination, what is the most probable cause of Sam's gynaecomastia?
Your Answer: Digoxin
Explanation:Digoxin is the correct answer as it can lead to drug-induced gynaecomastia. Sam is likely taking digoxin due to his heart failure, and this medication has a side effect of causing breast tissue growth in men. This is thought to occur because digoxin has a similar structure to oestrogen and can directly stimulate oestrogen receptors.
While cirrhosis can also cause gynaecomastia, it is unlikely in this case as there are no signs or symptoms of liver disease. Cirrhosis typically causes gynaecomastia due to the liver’s reduced ability to clear oestrogens from the bloodstream.
Obesity is not the correct answer as Sam is not obese, with a BMI of 24 kg/m². However, obesity is a common cause of gynaecomastia as excess fat can be distributed to the breasts and result in increased aromatisation of androgens to oestrogens.
An oestrogen-secreting tumour is not the correct answer as there is no evidence in Sam’s history or examination to suggest he has one, although these tumours can cause gynaecomastia in men.
Understanding Gynaecomastia: Causes and Drug Triggers
Gynaecomastia is a condition characterized by the abnormal growth of breast tissue in males, often caused by an increased ratio of oestrogen to androgen. It is important to distinguish the causes of gynaecomastia from those of galactorrhoea, which is caused by the actions of prolactin on breast tissue.
Physiological changes during puberty can lead to gynaecomastia, but it can also be caused by syndromes with androgen deficiency such as Kallmann and Klinefelter’s, testicular failure due to mumps, liver disease, testicular cancer, and hyperthyroidism. Additionally, haemodialysis and ectopic tumour secretion can also trigger gynaecomastia.
Drug-induced gynaecomastia is also a common cause, with spironolactone being the most frequent trigger. Other drugs that can cause gynaecomastia include cimetidine, digoxin, cannabis, finasteride, GnRH agonists like goserelin and buserelin, oestrogens, and anabolic steroids. However, it is important to note that very rare drug causes of gynaecomastia include tricyclics, isoniazid, calcium channel blockers, heroin, busulfan, and methyldopa.
In summary, understanding the causes and drug triggers of gynaecomastia is crucial in diagnosing and treating this condition.
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This question is part of the following fields:
- Endocrine System
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Question 11
Incorrect
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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: Turner syndrome (45,X0)
Correct 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.
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This question is part of the following fields:
- Endocrine System
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Question 12
Correct
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As a medical student on community care placement, I was shadowing a health visitor who measured the height and weight of all the children to monitor their growth. I was curious to know what drives growth during the adolescent stage (13 to 19 years old)?
Your Answer: Sex steroids and growth hormone
Explanation:Understanding Growth and Factors Affecting It
Growth is a significant difference between children and adults, and it occurs in three stages: infancy, childhood, and puberty. Several factors affect fetal growth, including environmental, placental, hormonal, and genetic factors. Maternal nutrition and uterine capacity are the most crucial environmental factors that affect fetal growth.
In infancy, nutrition and insulin are the primary drivers of growth. High fetal insulin levels result from poorly controlled diabetes in the mother, leading to hypoglycemia and macrosomia in the baby. Growth hormone is not a significant factor in infancy, as babies have low amounts of receptors. Hypopituitarism and thyroid have no effect on growth in infancy.
In childhood, growth is driven by growth hormone and thyroxine, while in puberty, growth is driven by growth hormone and sex steroids. Genetic factors are the most important determinant of final adult height.
It is essential to monitor growth in children regularly. Infants aged 0-1 years should have at least five weight recordings, while children aged 1-2 years should have at least three weight recordings. Children older than two years should have annual weight recordings. Children below the 2nd centile for height should be reviewed by their GP, while those below the 0.4th centile for height should be reviewed by a paediatrician.
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This question is part of the following fields:
- Endocrine System
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Question 13
Incorrect
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A 25-year-old woman visits the endocrinology department for weight management issues. She has been struggling with her weight since she was a child and currently has a BMI of 46 kg/m². Despite eating large portions at meals, she never feels full and snacks between meals. Her parents and two older siblings are all at a healthy weight. Genetic testing reveals a de novo mutation in the satiety signalling pathway. Which hormone's decreased synthesis may be responsible for her condition?
Your Answer: Ghrelin
Correct Answer: Leptin
Explanation:Leptin is the hormone that lowers appetite, while ghrelin is the hormone that increases appetite. Leptin is produced by adipose tissue and plays a crucial role in regulating feelings of fullness and satiety. Mutations that affect leptin signaling can lead to severe childhood-onset obesity. On the other hand, ghrelin is known as the hunger hormone and stimulates appetite. However, decreased ghrelin synthesis does not cause obesity. Insulin is an anabolic hormone that promotes glucose uptake and lipogenesis, while obestatin’s role in satiety is still controversial.
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.
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This question is part of the following fields:
- Endocrine System
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Question 14
Incorrect
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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: Thyroid function tests
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.
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This question is part of the following fields:
- Endocrine System
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Question 15
Incorrect
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A 65-year-old woman with hypocalcaemia has elevated parathyroid hormone levels. Is it a typical physiological response to increase calcium levels? In the kidney, where does parathyroid hormone act to enhance calcium reabsorption?
Your Answer: Bowman's capsule
Correct Answer: Distal convoluted tubule
Explanation: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.
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This question is part of the following fields:
- Endocrine System
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Question 16
Correct
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Which of the following is not secreted by the islets of Langerhans?
Your Answer: Secretin
Explanation:Mucosal cells in the duodenum and jejunum release secretin.
Hormones Released from the Islets of Langerhans
The islets of Langerhans in the pancreas are responsible for the production and secretion of several hormones that play a crucial role in regulating blood glucose levels. The beta cells in the islets of Langerhans are responsible for producing insulin, which accounts for 70% of the total secretions. Insulin helps to lower blood glucose levels by promoting the uptake of glucose by cells and tissues throughout the body.
The alpha cells in the islets of Langerhans produce glucagon, which has the opposite effect of insulin. Glucagon raises blood glucose levels by stimulating the liver to release stored glucose into the bloodstream. The delta cells in the islets of Langerhans produce somatostatin, which helps to regulate the release of insulin and glucagon.
Finally, the F cells in the islets of Langerhans produce pancreatic polypeptide, which plays a role in regulating pancreatic exocrine function and appetite. Together, these hormones work to maintain a delicate balance of blood glucose levels in the body.
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This question is part of the following fields:
- Endocrine System
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Question 17
Incorrect
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Which one of the following is not a result of cortisol in the stress response?
Your Answer: Anti-inflammatory effects
Correct Answer: Hypoglycaemia
Explanation:Hyperglycaemia is caused by an effect that opposes insulin.
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, adrenocorticotropic 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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This question is part of the following fields:
- Endocrine System
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Question 18
Incorrect
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A 15-year-old male arrives at the emergency department with intense abdominal pain and a decreased Glasgow coma score (GCS). Over the past few weeks, he has been experiencing excessive urination, abnormal thirst, and weight loss. Laboratory results reveal:
Ketones 4.2 mmol/L (<0.6 mmol/L)
Glucose 20 mmol/L
pH 7.25
What is the probable cause of the acidosis and hyperketonemia in this case?Your Answer: Uncontrolled glycogenolysis
Correct Answer: Uncontrolled lipolysis
Explanation:The likely cause of the patient’s condition is diabetic ketoacidosis, which is a result of uncontrolled lipolysis. This process leads to an excess of free fatty acids that are eventually converted into ketone bodies. It is important to note that proteolysis, the breakdown of proteins into smaller polypeptides, does not yield ketone bodies and is not the cause of this condition. While glycogenolysis and gluconeogenesis are increased due to the lack of insulin and rise of glucagon, they do not result in acidosis or elevated levels of ketone bodies. It is ketogenesis, not ketolysis, that leads to the increased levels of ketone bodies.
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.
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This question is part of the following fields:
- Endocrine System
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Question 19
Incorrect
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A 54-year-old man with type 2 diabetes mellitus visits the Endocrinology clinic for evaluation. He is currently on maximum doses of metformin and glibenclamide, but his HbA1c levels have increased from 58 mmol/mol to 67 mmol/mol over the past six months. The consultant recommends adding sitagliptin as a third antidiabetic medication. What is the mechanism of action of this new medication?
Your Answer: Decrease blood glucose by inhibiting renal glucose re-uptake via sodium-glucose co-transporter 2( SGLT2)
Correct Answer: Inhibit the peripheral breakdown of incretins, enhancing their ability to stimulate insulin release
Explanation: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.
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This question is part of the following fields:
- Endocrine System
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Question 20
Incorrect
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A 70-year-old male has been diagnosed with polymyalgia rheumatica and prescribed prednisolone. What is the most likely adverse effect he may experience?
Your Answer: Weight loss
Correct Answer: Hyperglycaemia
Explanation:Hyperglycemia is the correct answer. Most patients who take steroids experience an increase in appetite and weight gain, so anorexia or weight loss are not appropriate responses.
Steroid hormones can also affect the aldosterone receptor in the collecting duct, potentially leading to hyponatremia.
Although changes in vision are possible due to steroid-induced cataracts, they are much less common.
High levels of non-endogenous steroids have several risk factors, including hyperglycemia, high blood pressure, obesity (particularly around the waist), muscle wasting, poor wound healing, and mood swings or depression.
Corticosteroids are commonly prescribed medications that can be taken orally or intravenously, or applied topically. They mimic the effects of natural steroids in the body and can be used to replace or supplement them. However, the use of corticosteroids is limited by their numerous side effects, which are more common with prolonged and systemic use. These side effects can affect various systems in the body, including the endocrine, musculoskeletal, gastrointestinal, ophthalmic, and psychiatric systems. Some of the most common side effects include impaired glucose regulation, weight gain, osteoporosis, and increased susceptibility to infections. Patients on long-term corticosteroids should have their doses adjusted during intercurrent illness, and the medication should not be abruptly withdrawn to avoid an Addisonian crisis. Gradual withdrawal is recommended for patients who have received high doses or prolonged treatment.
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This question is part of the following fields:
- Endocrine System
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