Endocrinology Exam Questions

Correct Answer: D

Rationale: Parathyroid hormone (PTH) is a hormone produced by the parathyroid glands in response to low blood calcium levels. Its main function is to raise calcium levels in the blood by acting on the bones, kidneys, and intestines. PTH stimulates the release of calcium from the bones, enhances the absorption of calcium by the intestines, and promotes the reabsorption of calcium by the kidneys. Therefore, it is secreted in increased amounts when blood calcium levels are below normal in order to maintain overall calcium balance in the body.

Correct Answer: A

Rationale: The most common cause of Addison's disease is autoimmune adrenalitis, also known as autoimmune adrenal insufficiency. In autoimmune adrenalitis, the adrenal glands are damaged by immune system-mediated processes, leading to their dysfunction. This autoimmune destruction typically presents as bilateral adrenal cortex atrophy due to the formation of granulomas. Therefore, the commonest cause of Addison's disease is the presence of granulomas in the adrenal glands, making option A, Granuloma, the correct choice.

Correct Answer: A

Rationale: Thyroid hormones, T3 (triiodothyronine) and T4 (thyroxine), play a crucial role in regulating metabolism in the body. They are responsible for increasing the metabolic rate of cells by influencing the production of proteins and controlling how the body uses energy. This increase in metabolic rate results in processes such as increased heart rate, enhanced nutrient breakdown, and higher body temperature. Thus, option A, "increase metabolic rate," is the correct statement regarding thyroid hormones (T3 and T4).

Correct Answer: B

Rationale: Anti-diuretic hormone (ADH), also known as vasopressin, is a hormone released by the pituitary gland in response to changes in blood osmolality, blood volume, and blood pressure. During hemorrhage (significant blood loss), the body experiences a decrease in blood volume and blood pressure. In response to this decrease in blood volume, ADH secretion is increased to help the body retain water and maintain blood pressure levels. Therefore, it is incorrect to say that ADH secretion is reduced during hemorrhage.

Correct Answer: A

Rationale: Cirrhosis is not a potential cause of elevated LDL cholesterol levels. The liver plays a significant role in cholesterol metabolism, and liver disease like cirrhosis can actually lead to decreased levels of LDL cholesterol. Elevated LDL cholesterol levels can be caused by conditions such as hypothyroidism, nephrotic syndrome, or the use of certain medications like thiazide diuretics.