Question

medullary carcinoma of the thyroid gland will result in: a decrease in calcitonin production. a compensatory parathyroid hyperplasia. an increase in thyroid hormone production. hypercalcemia

Explanation:

1. Analyze each option:

• Option 1: Medullary thyroid carcinoma arises from C - cells which produce calcitonin. In cancer, the C - cells may not function properly, but actually, medullary carcinoma can sometimes secrete abnormal amounts, but if we consider the effect on calcium regulation, parathyroid hormone (PTH) and calcitonin have opposite effects. Calcitonin lowers blood calcium, PTH raises it.
• Option 2: Medullary thyroid carcinoma is related to thyroid C - cells, not directly causing parathyroid hyperplasia as a compensatory mechanism. Parathyroid hyperplasia is more related to parathyroid gland itself or calcium - related feedback loops not directly from thyroid medullary carcinoma.
• Option 3: Medullary thyroid carcinoma is not related to the production of thyroid hormones (T3, T4) which are produced by follicular cells of the thyroid. So it does not cause an increase in thyroid hormone production.
• Option 4: Calcitonin (from thyroid C - cells) lowers blood calcium. In medullary carcinoma, if calcitonin production is disrupted (or if there is a change in the balance with PTH), and since PTH increases blood calcium, without proper calcitonin action (or due to other factors in the cancer - related changes), blood calcium levels can rise, leading to hypercalcemia. Also, sometimes medullary carcinoma can be associated with multiple endocrine neoplasia syndromes which can affect parathyroid glands and lead to increased PTH, but more directly, the disruption of calcitonin's calcium - lowering effect (or other mechanisms) can lead to hypercalcemia. The other options are incorrect: a decrease in calcitonin production is not the main result (and sometimes it can be increased in a dysregulated way), compensatory parathyroid hyperplasia is not a direct result, and thyroid hormone production is not affected as medullary carcinoma is from C - cells not follicular cells.

Answer:

D. hypercalcemia