According to the 2011 recommendations from the World Health Organization (WHO), HbA1c can now be used as a diagnostic test for diabetes. However, this is only applicable if stringent quality assurance tests are in place and the assays are standardized to criteria aligned with international reference values. Additionally, accurate measurement of HbA1c is only possible if there are no conditions present that could hinder its accuracy.

To diagnose diabetes using HbA1c, a value of 48 mmol/mol (6.5%) is recommended as the cut-off point. It’s important to note that a value lower than 48 mmol/mol (6.5%) does not exclude the possibility of diabetes, as glucose tests are still necessary for a definitive diagnosis.

When using glucose tests, the following criteria are considered diagnostic for diabetes mellitus:
– A random venous plasma glucose concentration greater than 11.1 mmol/l
– A fasting plasma glucose concentration greater than 7.0 mmol/l
– A two-hour plasma glucose concentration greater than 11.1 mmol/l, two hours after consuming 75g of anhydrous glucose in an oral glucose tolerance test (OGTT)

However, there are certain circumstances where HbA1c is not appropriate for diagnosing diabetes mellitus. These include:
– ALL children and young people
– Patients of any age suspected of having Type 1 diabetes
– Patients with symptoms of diabetes for less than two months
– Patients at high risk of diabetes who are acutely ill, such as those requiring hospital admission
– Patients taking medication that may cause a rapid rise in glucose levels, such as steroids or antipsychotics
– Patients with acute pancreatic damage, including those who have undergone pancreatic surgery
– Pregnant individuals
– Presence of genetic, hematologic, and illness-related factors that can influence HbA1c and its measurement.

Phaeochromocytoma is a rare neuroendocrine tumor that secretes catecholamines. It typically arises from chromaffin tissue in the adrenal medulla, but can also occur in extra-adrenal chromaffin tissue. The majority of cases are spontaneous and occur in individuals aged 40-50 years. However, up to 30% of cases are hereditary and associated with genetic mutations. About 10% of phaeochromocytomas are metastatic, with extra-adrenal tumors more likely to be metastatic.

The clinical features of phaeochromocytoma are a result of excessive catecholamine production. Symptoms are typically paroxysmal and include hypertension, headaches, palpitations, sweating, anxiety, tremor, abdominal and flank pain, and nausea. Catecholamines have various metabolic effects, including glycogenolysis, mobilization of free fatty acids, increased serum lactate, increased metabolic rate, increased myocardial force and rate of contraction, and decreased systemic vascular resistance.

Diagnosis of phaeochromocytoma involves measuring plasma and urine levels of metanephrines, catecholamines, and urine vanillylmandelic acid. Imaging studies such as abdominal CT or MRI are used to determine the location of the tumor. If these fail to find the site, a scan with metaiodobenzylguanidine (MIBG) labeled with radioactive iodine is performed. The highest sensitivity and specificity for diagnosis is achieved with plasma metanephrine assay.

The definitive treatment for phaeochromocytoma is surgery. However, before surgery, the patient must be stabilized with medical management. This typically involves alpha-blockade with medications such as phenoxybenzamine or phentolamine, followed by beta-blockade with medications like propranolol. Alpha blockade is started before beta blockade to allow for expansion of blood volume and to prevent a hypertensive crisis.

Congenital adrenal hyperplasia (CAH) is a group of inherited disorders that are caused by autosomal recessive genes. The majority of affected patients, over 90%, have a deficiency of the enzyme 21-hydroxylase. This enzyme is encoded by the 21-hydroxylase gene, which is located on chromosome 6p21 within the HLA histocompatibility complex. The second most common cause of CAH is a deficiency of the enzyme 11-beta-hydroxylase. The condition is rare, with an incidence of approximately 1 in 500 births in the UK. It is more prevalent in the offspring of consanguineous marriages.

The deficiency of 21-hydroxylase leads to a deficiency of cortisol and/or aldosterone, as well as an excess of precursor steroids. As a result, there is an increased secretion of ACTH from the anterior pituitary, leading to adrenocortical hyperplasia.

The severity of CAH varies depending on the degree of 21-hydroxylase deficiency. Female infants often exhibit ambiguous genitalia, such as clitoral hypertrophy and labial fusion. Male infants may have an enlarged scrotum and/or scrotal pigmentation. Hirsutism, or excessive hair growth, occurs in 10% of cases.

Boys with CAH often experience a salt-losing adrenal crisis at around 1-3 weeks of age. This crisis is characterized by symptoms such as vomiting, weight loss, floppiness, and circulatory collapse.

The diagnosis of CAH can be made by detecting markedly elevated levels of the metabolic precursor 17-hydroxyprogesterone. Neonatal screening is possible, primarily through the identification of persistently elevated 17-hydroxyprogesterone levels.

In infants presenting with a salt-losing crisis, the following biochemical abnormalities are observed: hyponatremia (low sodium levels), hyperkalemia (high potassium levels), metabolic acidosis, and hypoglycemia.

Boys experiencing a salt-losing crisis will require fluid resuscitation, intravenous dextrose, and intravenous hydrocortisone.

Affected females will require corrective surgery for their external genitalia. However, they have an intact uterus and ovaries and are capable of having children.

The long-term management of both sexes involves lifelong replacement of hydrocortisone (to suppress ACTH levels).

Addison’s disease is characterized by several classical biochemical features. One of these features is an elevated level of ACTH, which is the body’s attempt to stimulate the adrenal glands. Additionally, individuals with Addison’s disease often experience hyponatremia, which is a decrease in the level of sodium in the blood. Another common feature is hyperkalemia, which refers to an excessive amount of potassium in the blood. Furthermore, individuals with Addison’s disease may also experience hypercalcemia, which is an elevated level of calcium in the blood. Hypoglycemia, which is low blood sugar, is another characteristic feature of this disease. Lastly, metabolic acidosis, which refers to an imbalance in the body’s acid-base levels, is also commonly observed in individuals with Addison’s disease.

Thyroid storm is a rare condition that affects only 1-2% of patients with hyperthyroidism. However, it is crucial to diagnose it promptly because it has a high mortality rate of approximately 10%. Thyroid storm is often triggered by a physiological stressor, such as stopping antithyroid therapy prematurely, recent surgery or radio-iodine treatment, infections (especially chest infections), trauma, diabetic ketoacidosis or hyperosmolar diabetic crisis, thyroid hormone overdose, pre-eclampsia. It typically occurs in patients with Graves’ disease or toxic multinodular goitre and presents with sudden and severe hyperthyroidism. Symptoms include high fever (over 41°C), dehydration, rapid heart rate (greater than 140 beats per minute) with or without irregular heart rhythms, low blood pressure, congestive heart failure, nausea, jaundice, vomiting, diarrhea, abdominal pain, confusion, agitation, delirium, psychosis, seizures, or coma.

To diagnose thyroid storm, various blood tests should be conducted, including a full blood count, urea and electrolytes, blood glucose, coagulation screen, CRP, and thyroid profile (T4/T3 and TSH). A bone profile/calcium test should also be done as 10% of patients develop hypocalcemia. Blood cultures should be taken as well. Other important investigations include a urine dipstick/MC&S, chest X-ray, and ECG.

The management of thyroid storm involves several steps. Intravenous fluids, such as 1-2 liters of 0.9% saline, should be administered. Airway support and management should be provided as necessary. A nasogastric tube should be inserted if the patient is vomiting. Urgent referral for inpatient management is essential. Paracetamol (1 g PO/IV) can be given to reduce fever. Benzodiazepines, such as diazepam (5-20 mg PO/IV), can be used for sedation. Steroids, like hydrocortisone (100 mg IV), may be necessary if there is co-existing adrenal suppression. Antibiotics should be prescribed if there is an intercurrent infection. Beta-blockers, such as propranolol (80 mg PO), can help control heart rate. High-dose carbimazole (45-60 mg/day) is recommended.

This patient has presented with an Addisonian crisis, which is a rare but potentially catastrophic condition if not diagnosed promptly. It is more commonly seen in women than men and typically occurs between the ages of 30 and 50.

Addison’s disease is caused by insufficient production of steroid hormones by the adrenal glands, affecting the production of glucocorticoids, mineralocorticoids, and sex steroids. The main causes of Addison’s disease include autoimmune adrenalitis (accounting for 80% of cases), bilateral adrenalectomy, Waterhouse-Friderichsen syndrome (hemorrhage into the adrenal glands), and tuberculosis.

The most common trigger for an Addisonian crisis in patients with Addison’s disease is the intentional or accidental withdrawal of steroid therapy. Other factors that can precipitate a crisis include infection, trauma, myocardial infarction, cerebral infarction, asthma, hypothermia, and alcohol abuse.

Clinical features of Addison’s disease include weakness, lethargy, hypotension (especially orthostatic hypotension), nausea, vomiting, weight loss, reduced axillary and pubic hair, depression, and hyperpigmentation (particularly in palmar creases, buccal mucosa, and exposed areas). In an Addisonian crisis, the main symptoms are usually hypoglycemia and shock, characterized by tachycardia, peripheral vasoconstriction, hypotension, altered consciousness, and even coma.

Biochemical markers of Addison’s disease typically include increased ACTH levels (as a compensatory response to stimulate the adrenal glands), elevated serum renin levels, hyponatremia, hyperkalemia, hypercalcemia, hypoglycemia, and metabolic acidosis. Confirmatory investigations may involve the Synacthen test, plasma ACTH level measurement, plasma renin level measurement, and testing for adrenocortical antibodies.

Management of Addison’s disease should be overseen by an Endocrinologist. Treatment usually involves the administration of hydrocortisone, fludrocortisone, and dehydroepiandrosterone. Some patients may also require thyroxine if there is concurrent hypothalamic-pituitary disease. Treatment is lifelong, and patients should carry a steroid card and MedicAlert bracelet to alert healthcare professionals about their condition and the potential for an Addisonian crisis.

Addison’s disease occurs when the adrenal cortex is destroyed. The anterior pituitary gland produces and releases adrenocorticotropic hormone (ACTH), not the posterior pituitary gland. The adrenal cortex is responsible for producing cortisol, not the adrenal medulla.

Further Reading:

Addison’s disease, also known as primary adrenal insufficiency or hypoadrenalism, is a rare disorder caused by the destruction of the adrenal cortex. This leads to reduced production of glucocorticoids, mineralocorticoids, and adrenal androgens. The deficiency of cortisol results in increased production of adrenocorticotropic hormone (ACTH) due to reduced negative feedback to the pituitary gland. This condition can cause metabolic disturbances such as hyperkalemia, hyponatremia, hypercalcemia, and hypoglycemia.

The symptoms of Addison’s disease can vary but commonly include fatigue, weight loss, muscle weakness, and low blood pressure. It is more common in women and typically affects individuals between the ages of 30-50. The most common cause of primary hypoadrenalism in developed countries is autoimmune destruction of the adrenal glands. Other causes include tuberculosis, adrenal metastases, meningococcal septicaemia, HIV, and genetic disorders.

The diagnosis of Addison’s disease is often suspected based on low cortisol levels and electrolyte abnormalities. The adrenocorticotropic hormone stimulation test is commonly used for confirmation. Other investigations may include adrenal autoantibodies, imaging scans, and genetic screening.

Addisonian crisis is a potentially life-threatening condition that occurs when there is an acute deficiency of cortisol and aldosterone. It can be the first presentation of undiagnosed Addison’s disease. Precipitating factors of an Addisonian crisis include infection, dehydration, surgery, trauma, physiological stress, pregnancy, hypoglycemia, and acute withdrawal of long-term steroids. Symptoms of an Addisonian crisis include malaise, fatigue, nausea or vomiting, abdominal pain, fever, muscle pains, dehydration, confusion, and loss of consciousness.

There is no fixed consensus on diagnostic criteria for an Addisonian crisis, as symptoms are non-specific. Investigations may include blood tests, blood gas analysis, and septic screens if infection is suspected. Management involves administering hydrocortisone and fluids. Hydrocortisone is given parenterally, and the dosage varies depending on the age of the patient. Fluid resuscitation with saline is necessary to correct any electrolyte disturbances and maintain blood pressure. The underlying cause of the crisis should also be identified and treated. Close monitoring of sodium levels is important to prevent complications such as osmotic demyelination syndrome.

An Addisonian crisis is characterized by several distinct features. These include experiencing pain in the legs and abdomen, as well as symptoms of vomiting and dehydration. Hypotension, or low blood pressure, is also commonly observed during an Addisonian crisis. Confusion and psychosis may also occur, along with the presence of a fever. In some cases, convulsions may be present as well. Additionally, individuals experiencing an Addisonian crisis may also exhibit hypoglycemia, hyponatremia, hyperkalemia, hypercalcemia, eosinophilia, and metabolic acidosis.

The initial noticeable abnormality in sensory testing for diabetic neuropathy is often the loss of vibration sense. Reduced sensation, particularly in vibration sense, is typically the first symptom to be observed in diabetic neuropathy.

Further Reading:

Diabetic foot is a complication that can occur in individuals with diabetes due to long-standing high blood sugar levels. This leads to a process called glycation or glycosylation, where glucose binds to proteins and lipids in the body. Abnormal protein glycation can cause cellular dysfunction and various complications.

One of the main problems in diabetic foot is peripheral vascular disease and peripheral neuropathy. These conditions can result in significant foot issues, as trauma to the feet may go unnoticed and untreated. Vascular disease also impairs wound healing and increases the risk of developing ulcers.

Clinical features of diabetic foot include reduced sensation, especially to vibration, non-dermatomal sensory loss, foot deformities such as pes cavus and claw toes, and weak or absent foot pulses. It is important for diabetic patients to have their feet assessed regularly, at least annually, to identify any potential problems. Additional foot assessments should also be conducted during hospital admissions.

During a diabetic foot assessment, the healthcare provider should remove shoes, socks, and any bandages or dressings to examine both feet. They should assess for neuropathy using a 10 g monofilament to test foot sensation and check for limb ischemia by examining pulses and performing ankle brachial pressure index (ABPI) measurements. Any abnormal tissue, such as ulcers, calluses, infections, inflammation, deformities, or gangrene, should be documented. The risk of Charcot arthropathy should also be assessed.

The severity of foot ulcers in diabetic patients can be documented using standardized systems such as SINBAD or the University of Texas classification. The presence and severity of diabetic foot infection can be determined based on criteria such as local swelling, induration, erythema, tenderness, pain, warmth, and purulent discharge.

Management of foot ulcers involves offloading, control of foot infection, control of ischemia, wound debridement, and appropriate wound dressings. Antibiotics may be necessary depending on the severity of the infection. Diabetic patients with foot ulcers should undergo initial investigations including blood tests, wound swabs, and imaging to assess for possible osteomyelitis.

Charcot foot is a serious complication of diabetic peripheral neuropathy that results in progressive destructive arthropathy and foot deformity. Signs of Charcot foot include redness, swelling, warm skin, pain, and deformity. The hallmark deformity is midfoot collapse, known as the rocker-bottom foot.

After the fluid restriction period, the urine is checked to determine if it remains relatively dilute (less than 600 mOsm/kg). If it does, desmopressin is administered and the urine is rechecked to see if it responds and becomes more concentrated.

If the urine osmolality significantly increases after desmopressin, it indicates that the kidneys have responded appropriately to the medication and the urine has concentrated. This suggests that the patient is not producing ADH in response to water loss, indicating cranial DI.

It is important to note that some units may use a lower cut-off of greater than 600 mOsm/kg instead of 800 mOsm/kg.

Further Reading:

Diabetes insipidus (DI) is a condition characterized by either a decrease in the secretion of antidiuretic hormone (cranial DI) or insensitivity to antidiuretic hormone (nephrogenic DI). Antidiuretic hormone, also known as arginine vasopressin, is produced in the hypothalamus and released from the posterior pituitary. The typical biochemical disturbances seen in DI include elevated plasma osmolality, low urine osmolality, polyuria, and hypernatraemia.

Cranial DI can be caused by various factors such as head injury, CNS infections, pituitary tumors, and pituitary surgery. Nephrogenic DI, on the other hand, can be genetic or result from electrolyte disturbances or the use of certain drugs. Symptoms of DI include polyuria, polydipsia, nocturia, signs of dehydration, and in children, irritability, failure to thrive, and fatigue.

To diagnose DI, a 24-hour urine collection is done to confirm polyuria, and U&Es will typically show hypernatraemia. High plasma osmolality with low urine osmolality is also observed. Imaging studies such as MRI of the pituitary, hypothalamus, and surrounding tissues may be done, as well as a fluid deprivation test to evaluate the response to desmopressin.

Management of cranial DI involves supplementation with desmopressin, a synthetic form of arginine vasopressin. However, hyponatraemia is a common side effect that needs to be monitored. In nephrogenic DI, desmopressin supplementation is usually not effective, and management focuses on ensuring adequate fluid intake to offset water loss and monitoring electrolyte levels. Causative drugs need to be stopped, and there is a risk of developing complications such as hydroureteronephrosis and an overdistended bladder.