A patient presented with headache and flushing. He has a family history of his relative having died of a Medullary ca of thyroid. . The investigation that would be required for this patient would be:
**Core Concept**
The patient's symptoms and family history are suggestive of Multiple Endocrine Neoplasia Type 2B (MEN 2B), a genetic disorder characterized by the development of medullary thyroid carcinoma (MTC), pheochromocytoma, and other endocrine tumors. The investigation of choice for this patient would be one that can detect the genetic mutation responsible for MEN 2B.
**Why the Correct Answer is Right**
The correct investigation for MEN 2B is a genetic test for the RET proto-oncogene, which is the gene responsible for this disorder. The RET gene mutation leads to the development of MTC and other endocrine tumors. The genetic test can detect the presence of the mutation, allowing for early detection and treatment of the disease. This is particularly important for patients with a family history of MEN 2B, as they are at increased risk of developing the disease.
**Why Each Wrong Option is Incorrect**
**Option A:** Serum calcitonin levels are not a diagnostic test for MEN 2B, although elevated levels may be seen in patients with MTC.
**Option B:** Fine-needle aspiration biopsy of the thyroid gland may be used to diagnose MTC, but it is not the investigation of choice for MEN 2B.
**Option C:** Octreotide scan is a diagnostic tool for certain types of endocrine tumors, but it is not the investigation of choice for MEN 2B.
**Clinical Pearl / High-Yield Fact**
MEN 2B is an autosomal dominant disorder, meaning that a single copy of the mutated gene is sufficient to cause the disease. Patients with a family history of MEN 2B should undergo genetic testing to detect the RET gene mutation.
**Correct Answer:** D. Genetic test for the RET proto-oncogene.