Hyperprolactinemia can cause the following except:

Correct Answer: C

Rationale: Hyperprolactinemia causes an increase in prolactin levels, which can lead to amenorrhea due to inhibition of gonadotropin-releasing hormone, gynecomastia due to decreased testosterone levels, and depressed fertility due to disrupted ovulation. Multiple ovulation is not typically a direct consequence of hyperprolactinemia, as it primarily affects the menstrual cycle and fertility. Therefore, the correct answer is C.

Correct Answer: D

Rationale: The correct answer is D: Serum TSH level. Serum TSH level is the most reliable guide for adjusting thyroxine dose in hypothyroidism because it directly reflects the body's feedback mechanism to regulate thyroid hormone levels. Elevated TSH indicates the body is trying to stimulate the thyroid gland to produce more hormone, suggesting the need for an increase in thyroxine dose. Conversely, low TSH levels indicate potential over-replacement, necessitating a reduction in thyroxine dose. Pulse rate (A) and body weight (B) can be influenced by various factors and are not specific indicators of thyroid hormone levels. Serum thyroxine level (C) can be affected by the timing of the last medication dose and does not provide feedback on the body's overall thyroid status like TSH does.

Correct Answer: C

Rationale: Step-by-step rationale for correct answer (C): 1. Radioactive iodine destroys overactive thyroid tissue, reducing hormone production. 2. Unlike anti-thyroid medications (A and B), radioactive iodine does not directly inhibit thyroid function. 3. Sodium thiocyanate (D) inhibits iodine uptake by the thyroid, potentially leading to goiter. Summary of incorrect choices: A. Propyl thiouracil and B. Carbimazole are anti-thyroid medications that can cause goiter in overdose. D. Sodium thiocyanate can lead to goiter by interfering with iodine uptake.

Correct Answer: C

Rationale: Correct Answer: C) Carbimazole does not produce an active metabolite. Rationale: 1. Carbimazole is a prodrug that is converted to its active form, methimazole, in the body. 2. Methimazole is the active compound responsible for inhibiting thyroid hormone production. 3. Propylthiouracil, on the other hand, directly inhibits thyroid hormone synthesis without needing conversion. 4. Therefore, Carbimazole differs from propylthiouracil in that it requires metabolic activation to its active form, methimazole, and does not produce a different active metabolite like propylthiouracil does. Summary: A) Incorrect: Carbimazole is not dose to dose less potent compared to propylthiouracil; potency can vary based on individual response. B) Incorrect: Carbimazole actually has a longer plasma half-life compared to propylthiouracil. D) Incorrect: Carbim

Correct Answer: B

Rationale: The correct answer is B: Young adults with recent onset of Grave's disease. Radioactive iodine is the treatment of choice for this category of thyrotoxic patients because it effectively destroys the overactive thyroid tissue, providing a long-term solution. Children are not typically treated with radioactive iodine due to concerns about potential long-term effects on growth and development. Elderly patients with ischaemic heart disease may not be suitable candidates due to the risk of exacerbating heart conditions. Pregnant women should not receive radioactive iodine treatment as it can harm the developing fetus. Therefore, the most appropriate choice is B based on the effectiveness and safety considerations for each category of patients.