Medullary ca of thyroid is associated with increase in-
**Core Concept**
Medullary carcinoma (ca) of the thyroid is a type of cancer that originates from the parafollicular cells (also known as C cells) of the thyroid gland. These cells produce calcitonin, a hormone involved in calcium and phosphorus metabolism.
**Why the Correct Answer is Right**
Medullary thyroid carcinoma (MTC) is characterized by an abnormal increase in calcitonin production. This hormone is secreted in response to elevated calcium levels in the blood. In MTC, the cancer cells produce and secrete calcitonin, which can be used as a tumor marker for diagnosis and monitoring of the disease. The increased calcitonin levels can be detected in the blood and are often used to diagnose and follow up MTC.
**Why Each Wrong Option is Incorrect**
**Option A:**
There is no direct association between medullary thyroid carcinoma and increased parathyroid hormone (PTH) levels.
**Option B:**
While medullary thyroid carcinoma can cause hypercalcemia due to increased calcitonin production, there is no direct association with increased gastrin levels.
**Option C:**
Medullary thyroid carcinoma is not associated with increased levels of antidiuretic hormone (ADH).
**Clinical Pearl / High-Yield Fact**
It's essential to remember that calcitonin is a tumor marker for medullary thyroid carcinoma, and elevated levels can indicate the presence of this disease.
**Correct Answer:** D. Calcitonin