Which of the following is a steroid 5α-reductase inhibitor that has been found useful in benign prostatic hypertrophy and male pattern baldness:

Correct Answer: B

Rationale: Finasteride is a steroid 5α-reductase inhibitor that has been found useful in treating benign prostatic hypertrophy (BPH) and male pattern baldness. By inhibiting the enzyme 5α-reductase, finasteride reduces the conversion of testosterone to dihydrotestosterone (DHT), which is implicated in both conditions. In BPH, DHT contributes to prostate enlargement, while in male pattern baldness, it contributes to the miniaturization of hair follicles. Finasteride helps in reducing DHT levels, leading to improvements in both conditions. It is a well-established and commonly prescribed medication for these purposes.

Correct Answer: B

Rationale: Estrogen replacement therapy in menopausal women has been associated with an increased risk of endometrial carcinoma due to unopposed estrogen stimulation. Adding a progestin for 10-12 days each month helps to counteract this risk by providing progestational support, which protects the endometrium from estrogen-induced hyperplasia and potential malignant transformation. This combination therapy is known as hormone replacement therapy and is commonly recommended to reduce the risk of endometrial carcinoma in menopausal women receiving estrogen therapy.

Correct Answer: D

Rationale: Oxytocin is a hormone that plays a crucial role in both the initiation of labor (A) and the milk ejection reflex (C) in breastfeeding mothers. During childbirth, oxytocin helps to stimulate contractions of the uterus, which are necessary for labor to progress. After childbirth, oxytocin continues to be important in the production and release of milk. When a baby suckles at the breast, oxytocin is released, causing the milk to be ejected from the mother's mammary glands, facilitating breastfeeding. Thus, oxytocin is essential for both the initiation of labor and the milk ejection reflex.

Correct Answer: A

Rationale: Hyper-vitaminosis D refers to an excessive intake of vitamin D leading to an elevated level of calcium in the blood (hypercalcemia). The common features of hyper-vitaminosis D include symptoms such as fatigue, weakness, nausea, vomiting, dehydration, and kidney disorders. However, hypertension is not a typical feature associated with hyper-vitaminosis D. Instead, hypertension is commonly associated with conditions such as high salt intake, obesity, and stress. Hence, hypertension is not a feature of hyper-vitaminosis D.

Correct Answer: D

Rationale: Parathormone, also known as parathyroid hormone (PTH), is a hormone secreted by the parathyroid glands. Its primary function is to regulate calcium and phosphate levels in the blood. One of the main actions of parathormone is to increase the resorption of calcium from the bone. This means that PTH stimulates the osteoclasts in bone tissue to break down bone matrix, releasing calcium into the bloodstream. This helps to increase the levels of calcium in the blood when they are low. The other functions of parathormone include increasing calcium reabsorption in the kidneys and promoting the formation of active vitamin D, which enhances calcium absorption in the intestines.