What laboratory test is typically elevated in a patient with a carcinoid tumor?

What laboratory test is typically elevated in a patient with a carcinoid tumor?

• A. Serotonin
• B. Calcitonin
• C. Glucagon
• D. Histamine

Answer: (A)

In patients with carcinoid tumors, the laboratory test that is typically elevated is serotonin. Carcinoid tumors are neuroendocrine tumors that often arise in the gastrointestinal tract, particularly within the small intestine, and they frequently secrete serotonin, a chemical that can lead to various clinical symptoms and complications. Elevated serotonin levels can be detected in the urine as 5-hydroxyindoleacetic acid (5-HIAA), which is a metabolite of serotonin. The measurement of 5-HIAA in a 24-hour urine specimen is a standard diagnostic test for carcinoid syndrome, which may present with symptoms such as flushing, diarrhea, and wheezing caused by excessive serotonin production. Therefore, the elevation of serotonin or its metabolites is a hallmark of the presence of these tumors. Other hormones mentioned in the choices, such as calcitonin, glucagon, and histamine, are associated with different types of neuroendocrine tumors or other conditions. They are not characteristically elevated in patients with carcinoid tumors, making serotonin the definitive laboratory marker for this specific type of tumor.

In patients with carcinoid tumors, the laboratory test that is typically elevated is serotonin. Carcinoid tumors are neuroendocrine tumors that often arise in the gastrointestinal tract, particularly within the small intestine, and they frequently secrete serotonin, a chemical that can lead to various clinical symptoms and complications.

Elevated serotonin levels can be detected in the urine as 5-hydroxyindoleacetic acid (5-HIAA), which is a metabolite of serotonin. The measurement of 5-HIAA in a 24-hour urine specimen is a standard diagnostic test for carcinoid syndrome, which may present with symptoms such as flushing, diarrhea, and wheezing caused by excessive serotonin production. Therefore, the elevation of serotonin or its metabolites is a hallmark of the presence of these tumors.

Other hormones mentioned in the choices, such as calcitonin, glucagon, and histamine, are associated with different types of neuroendocrine tumors or other conditions. They are not characteristically elevated in patients with carcinoid tumors, making serotonin the definitive laboratory marker for this specific type of tumor.