Nokea
Thyroid-stimulating hormone (TSH):
- A. is synthesized in parafollicular cells
- B. is a template for thyroid hormone biosynthesis.
- C. is derived from iodinated tyrosine residues.
- D. secretion is inhibited by TRH from the hypothalamus.
Correct Answer: D
Rationale: Thyroid-stimulating hormone (TSH) is a hormone produced by the anterior pituitary gland. It stimulates the thyroid gland to produce and release thyroid hormones, specifically thyroxine (T4) and triiodothyronine (T3). TSH secretion is regulated by the hypothalamus via the release of thyrotropin-releasing hormone (TRH). TRH acts on the anterior pituitary gland to stimulate the production and release of TSH. Therefore, TSH secretion is indeed inhibited by TRH, not stimulated as in the other options.
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Which of the following is a complication of diabetes mellitus?
- A. Gastroparesis
- B. Exophthalmos
- C. Hirsutism
- D. Moon facies
Correct Answer: A
Rationale: Gastroparesis is a complication of diabetes mellitus. It is a condition that affects the normal spontaneous movement of the muscles in the stomach, causing delayed emptying of food from the stomach into the small intestine. This can lead to symptoms such as nausea, vomiting, bloating, and poor appetite. Diabetes can damage the nerves that control the stomach muscles, resulting in gastroparesis. Managing blood sugar levels and following a proper diet can help in controlling the symptoms of gastroparesis in individuals with diabetes. Exophthalmos, hirsutism, and moon facies are not typically associated with complications of diabetes mellitus.
Calcification of basal ganglia is seen in:
- A. Primary hyperparathyroidism
- B. Hypoparathyroidism
- C. Secondary hyperparathyroidism
- D. Milk-alkali syndrome
Correct Answer: A
Rationale: Primary hyperparathyroidism is a condition characterized by the overproduction of parathyroid hormone (PTH) by the parathyroid glands, leading to elevated levels of calcium in the blood. This excessive calcium can cause calcification in various tissues, including the basal ganglia of the brain. The calcification of the basal ganglia in primary hyperparathyroidism is a well-known radiological finding and can be visualized on imaging studies such as CT scans or MRI. Hypoparathyroidism, on the other hand, is characterized by low levels of PTH and results in decreased serum calcium levels, making it an unlikely cause of basal ganglia calcification. Secondary hyperparathyroidism is associated with chronic kidney disease and is also characterized by high PTH levels, but basal ganglia calcification is not a typical manifestation of this condition. Milk-alkali syndrome is a disorder characterized by excessive intake of
Commonest cause of phaeochromocytoma is:
- A. Tumour of adrenal medulla
- B. Necrosis of adrenal gland
- C. Small cell carcinoma of bronchus
- D. Adrenal cortical hyperplasia
Correct Answer: A
Rationale: Phaeochromocytoma is a neuroendocrine tumor that arises from the chromaffin cells of the adrenal medulla. It is the most common cause of a catecholamine-secreting tumor in adults. While it can also rarely occur outside the adrenal gland (referred to as extra-adrenal or paraganglioma), the majority of cases originate within the adrenal medulla. Symptoms of phaeochromocytoma are due to the excessive release of catecholamines (epinephrine and norepinephrine), leading to a characteristic triad of headaches, sweating, and palpitations. Therefore, the commonest cause of phaeochromocytoma is a tumor of the adrenal medulla.
Which of the following does the adrenal cortex produce?
- A. Adrenaline
- B. Aldosterone
- C. Cortisol
- D. Noradrenaline
Correct Answer: B
Rationale: The adrenal cortex is the outer region of the adrenal glands and is responsible for producing several hormones, including aldosterone. Aldosterone is a mineralocorticoid hormone that plays a crucial role in regulating electrolyte balance, particularly sodium and potassium, in the body. It helps maintain blood pressure and fluid balance by acting on the kidneys to reabsorb sodium and water while excreting potassium in the urine. Adrenaline and noradrenaline (also known as epinephrine and norepinephrine) are produced by the adrenal medulla, which is the inner region of the adrenal glands. Cortisol is another hormone produced by the adrenal cortex, but aldosterone specifically regulates electrolyte balance.
Commonest cause of 'ambiguous genitalia' in newborn is:
- A. Congenital adrenal hyperplasia
- B. True hermaphroditism
- C. Testicular ferminisation syndrome
- D. Pseudo-hermaphroditism
Correct Answer: A
Rationale: Congenital adrenal hyperplasia (CAH) is the most common cause of ambiguous genitalia in newborns. This condition is due to a deficiency of enzymes in the adrenal gland that are necessary for the production of cortisol. As a result, the body produces excess androgens (masculinizing hormones), leading to abnormal genital development in females. The external genitalia may appear ambiguous, with features of both male and female genitalia. This condition can be detected through newborn screening and confirmed through further hormonal and genetic testing. Treatment involves hormone replacement therapy to normalize hormone levels and surgery may be required to reconstruct the genitalia.