Serum TSH levels are high in most cases of:

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: 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.

Correct Answer: A

Rationale: Insulin release is primarily stimulated by glucose. Ketone bodies are produced during fasting or low-carb diets and do not directly stimulate insulin release. Glucagon stimulates glycogen breakdown and opposes insulin. Vagal stimulation can enhance insulin release through parasympathetic nervous system activation. Alpha adrenergic agonists like epinephrine inhibit insulin release. Therefore, the correct answer is A as ketone bodies do not directly augment insulin release.

Correct Answer: B

Rationale: The correct answer is B: Subcutaneous. Insulin is typically administered subcutaneously because it allows for slow and consistent absorption into the bloodstream. Intradermal administration is not ideal for insulin as it may cause skin irritation. Intramuscular administration can lead to erratic absorption and unpredictable blood sugar levels. Intravenous administration is too rapid and can cause dangerous hypoglycemia. Subcutaneous administration provides a balance of absorption rate and is the most common and effective route for insulin delivery.