Gonadotropins are indicated in the following conditions except:

Correct Answer: B

Rationale: The correct answer is B: Cryptorchism in a boy less than 7 years old. Gonadotropins are not indicated in cryptorchism as it is a condition where one or both testes fail to descend into the scrotum. Gonadotropins are used to treat conditions like hypogonadotrophic hypogonadism, amenorrhoea, infertility, and polycystic ovaries by stimulating the production of sex hormones. For the other choices: A) Hypogonadotrophic hypogonadism in males - correct, as gonadotropins can help stimulate testosterone production. C) Amenorrhoea and infertility in women - correct, as gonadotropins can help induce ovulation. D) Polycystic ovaries - correct, as gonadotropins can help regulate hormone levels and promote ovulation.

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.

Correct Answer: B

Rationale: The correct answer is B: Tyrosine protein kinase receptor. The insulin receptor is a type of receptor that belongs to the tyrosine kinase family. It works by phosphorylating tyrosine residues on itself and other proteins, triggering a signaling cascade that regulates glucose uptake and metabolism. This process is crucial for maintaining blood glucose levels. Option A is incorrect because the insulin receptor is not an ion channel regulating receptor. Option C is incorrect as the insulin receptor does not belong to the G-protein coupled receptor family. Option D is incorrect as the insulin receptor is indeed a tyrosine protein kinase receptor.