**Question:** All are pas of MEN-1 except

A. Parathyroid hormone (PTH)
B. Calcitonin
C. Secretin
D. Somatostatin

**Core Concept:** Multiple Endocrine Neoplasia Type 1 (MEN-1) is a genetic disorder characterized by the development of tumors in endocrine glands, mainly in the parathyroid, pancreas, and pituitary glands. MEN-1 is caused by mutations in the MEN1 gene, which encodes the protein Menin. This protein plays a crucial role in preventing the uncontrolled growth of endocrine cells.

**Why the Correct Answer is Right:** Secretin is not a part of MEN-1 because it is involved in the regulation of gastric acid secretion and the secretion of bicarbonate into the small intestine, specifically in response to the presence of acids in the distal small intestine. Secretin is produced by the specialized cells in the distal part of the duodenum and secreted into the portal vein, which then goes to the pancreaticoduodenal gland to stimulate the release of bicarbonate into the small intestine.

**Why Each Wrong Option is Incorrect:**

A. Parathyroid hormone (PTH): PTH is a key hormone involved in regulating calcium and phosphorus levels in the blood. It is released by the chief cells in the parathyroid glands in response to low calcium levels in the blood, stimulating the release of calcium from bones and the reabsorption of calcium from the kidneys and intestines. PTH is not related to MEN-1.

B. Calcitonin: Calcitonin is a hormone produced by the parafollicular cells in the C cells of the thyroid gland. It plays a crucial role in regulating serum calcium levels by inhibiting the release of calcium from bones and stimulating calcium excretion in the kidneys and intestines. Calcitonin is not involved in MEN-1.

C. Secretin: As mentioned before, secretin is involved in regulating gastric acid secretion and bicarbonate secretion in the small intestine, not related to MEN-1.

D. Somatostatin: Somatostatin is a hormone produced by the D cells in the pancreas and the G cells in the stomach. It regulates various endocrine functions, including growth hormone, insulin, glucagon, and gastrin release. Somatostatin is not a part of MEN-1.

**Clinical Pearls:**

1. MEN-1 is a genetic disorder caused by mutations in the MEN1 gene, which encodes the protein Menin. Mutations in this gene lead to uncontrolled growth of endocrine cells in various glands, including parathyroid, pancreatic, and pituitary glands.
2. The main clinical manifestations of MEN-1 include primary hyperparathyroidism, pancreatic neuroendocrine tumors, and pituitary adenomas.
3. These tumors can lead to hypersecretion of hormones, which can cause symptoms like hypertension, osteoporosis, diabetes mellitus, and neurological symptoms.
4. MEN-1 is a