Indications of somatostatin include:

Correct Answer: C

Rationale: Rationale for correct answer C: Somatostatin is used to treat bleeding esophageal varices by reducing portal pressure, inhibiting vasodilation, and decreasing blood flow to the varices. This helps in preventing further bleeding episodes and stabilizing the condition. The other choices are incorrect because: A: Macroprolactinoma is usually treated with dopamine agonists, not somatostatin. B: Zollinger Ellison syndrome is treated with proton pump inhibitors or H2 blockers, not somatostatin. D: Steatorrhoea is not typically treated with somatostatin; it is usually managed with dietary modifications or pancreatic enzyme replacement therapy.

Correct Answer: A

Rationale: The correct answer is A: Myxoedema. High serum TSH levels indicate primary hypothyroidism, which is characterized by decreased thyroid hormone levels. Myxoedema is a severe form of hypothyroidism where TSH levels increase as the body tries to stimulate the thyroid to produce more hormones. In Grave's disease (B), TSH levels are typically low due to thyroid overactivity. Carcinoma thyroid (C) may present with normal or slightly elevated TSH levels. Toxic nodular goiter (D) is associated with low TSH levels due to autonomous thyroid hormone production.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Thyroxine increases basal metabolic rate. 2. This leads to increased energy expenditure. 3. Increased energy expenditure can lead to negative nitrogen balance. 4. Therefore, induction of negative nitrogen balance is an action of thyroxine. 5. The other choices are incorrect as thyroxine does reduce plasma cholesterol level, fall in plasma free fatty acid level, and rise in blood sugar level.

Correct Answer: B

Rationale: Carbimazole inhibits the oxidation of iodide by blocking the enzyme thyroid peroxidase. This enzyme is crucial for converting iodide to iodine, a key step in thyroid hormone synthesis. By inhibiting this step, carbimazole effectively reduces the production of thyroid hormones. Choice A is incorrect as iodide trapping is not directly affected by carbimazole. Choice C is incorrect as proteolysis of thyroglobulin is not the target of carbimazole. Choice D is incorrect as carbimazole does not interfere with the synthesis of thyroglobulin protein itself.

Correct Answer: B

Rationale: The correct answer is B: Preoperatively for 10-15 days. Lugol's iodine is used preoperatively in hyperthyroidism to reduce vascularity and size of the thyroid gland, making surgery safer. Administering it for 10-15 days before surgery allows for optimal effects. Choice A is incorrect because Lugol's iodine is not used as long term definitive monotherapy due to its potential side effects and limitations. Choice C is incorrect as Lugol's iodine is not typically used postoperatively for 10-15 days. Choice D is incorrect because Lugol's iodine is not used as an adjuvant to carbimazole for long term therapy; carbimazole is commonly used as a long-term therapy for hyperthyroidism.