Endocrinology Practice Questions

Correct Answer: A

Rationale: The correct answer is A because parathyroid hormone does not directly stimulate osteoblasts to increase bone formation. Instead, it indirectly increases bone resorption by stimulating osteoclasts. Parathyroid hormone also increases calcium reabsorption from the distal tubule of the kidney (choice C) and inhibits phosphate reabsorption in the proximal tubule of the kidney (choice D). By understanding the physiological actions of parathyroid hormone, we can deduce that direct stimulation of osteoblasts is not one of its functions.

Correct Answer: A

Rationale: The correct answer is A: Phaeochromocytoma. Multiple Endocrine Neoplasia Type I (MEN I) is characterized by tumors in the pituitary, pancreas, and parathyroid glands. Phaeochromocytoma is not typically associated with MEN I. Phaeochromocytoma is commonly seen in MEN II syndrome. Therefore, A is the correct answer. Choice B, C, and D are incorrect as they are all associated with MEN I based on the characteristic tumor involvement in the pituitary, pancreas, and parathyroid glands, respectively.

Correct Answer: B

Rationale: The correct answer is B: Cretinism. Cretinism is the most common cause of preventable mental deficiency worldwide due to severe iodine deficiency during pregnancy. Iodine is crucial for thyroid hormone production, which is essential for fetal brain development. Beriberi disease (A) is caused by thiamine deficiency and affects the nervous system, not mental deficiency. Folate deficiency (C) can cause neural tube defects but not mental deficiency. Vitamin A deficiency (D) can lead to blindness and immune system issues, but not the most common cause of preventable mental deficiency.

Correct Answer: C

Rationale: The correct answer is C: Purple skin striae. This is the most common sign of Cushing's syndrome due to the excessive production of cortisol leading to thinning of the skin and formation of purple stretch marks. Hirsutism (A) is excessive hair growth, not specific to Cushing's. Obesity (B) can be a symptom, but it is not the most common. Skin hyperpigmentation (D) is seen in Addison's disease, not Cushing's.

Correct Answer: C

Rationale: The correct answer is C: Ischaemic heart disease. Metabolic syndrome X consists of a cluster of conditions, including hyperlipidemia, obesity, hypertension, and insulin resistance. Ischaemic heart disease, while commonly associated with metabolic syndrome X due to the increased risk factors, is not a direct component of the syndrome itself. Therefore, it is not considered a part of metabolic syndrome X. Hyperlipidemia (A), obesity (B), and hypertension (D) are all key components of metabolic syndrome X due to their association with insulin resistance and increased risk of cardiovascular disease.