The carcinoma of thyroid associated with hypocalcemia is –
**Core Concept**
The question is testing the association between a specific type of thyroid carcinoma and its effect on calcium levels. This is related to the parathyroid glands, which are also affected in this condition, leading to hypocalcemia due to parathyroid hormone (PTH) deficiency.
**Why the Correct Answer is Right**
Medullary thyroid carcinoma (MTC) is a type of thyroid cancer that originates from the parafollicular cells, also known as C cells. These cells produce calcitonin, a hormone that lowers blood calcium levels. In MTC, the parathyroid glands are often affected, leading to destruction of the parathyroid tissue and subsequent hypocalcemia due to reduced PTH production. This is because the parathyroid glands are located near the thyroid gland and can be damaged during surgery or by the tumor itself.
**Why Each Wrong Option is Incorrect**
**Option A:** Papillary thyroid carcinoma is the most common type of thyroid cancer and is not typically associated with hypocalcemia. It is more likely to cause hypercalcemia due to increased calcitonin production.
**Option B:** Follicular thyroid carcinoma is a type of well-differentiated thyroid cancer that is not typically associated with hypocalcemia. It may cause hypercalcemia due to increased calcitonin production.
**Option C:** Anaplastic thyroid carcinoma is a rare and aggressive type of thyroid cancer that can cause hypercalcemia due to increased calcitonin production, but it is not typically associated with hypocalcemia.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that medullary thyroid carcinoma is the only type of thyroid cancer that produces calcitonin, which can lead to hypocalcemia due to reduced PTH production.
**Correct Answer:** D. Medullary thyroid carcinoma