A 39-year-old female presents with chronic abdominal cramps, watery diarrhea, and periodic facial flushing. Physical examination reveals wheezing and a slightly enlarged liver. Workup reveals several masses within the liver and a large mass in the small intestine. Which one of the listed substances is most likely to be elevated in the urine of this individual as a result of her disease?
The patient shows signs of the carcinoid syndrome, which include flushing, diarrhea, and bronchoconstriction. The syndrome results from elaboration of serotonin (5-hydroxytryptamine) by a primary carcinoid tumor in the lungs or ovary, or from hepatic metastases from a primary carcinoid tumor in the gastrointestinal tract. However, primary appendiceal carcinoid tumors, the most common gastrointestinal carcinoid tumors, very rarely metastasize and are viually always asymptomatic. Carcinoid tumors arise from cells of the neuroendocrine system, which, as pa of the amine precursor uptake and decarboxylation (APUD) system, are capable of secreting many products. Grossly, carcinoid tumors, which tend to be multiple when they occur in the stomach or intestines, are characteristically solid and firm and have a yellow-tan appearance on sectioning. Histologically they are composed of nests of relatively bland-appearing monotonous cells. Diagnosis is based on finding increased urinary 5-hydroxyindoleacetic acid (5-HIAA) excretion from metabolism of excess serotonin. In contrast, increased urinary levels of aminolevulinic acid (ALA) are seen with lead toxicity, increased N-formiminoglutamate (FIGlu) with folate deficiency, and increased normetanephrine or vanillylmandelic acid (VMA) with tumors of the adrenal medulla (pheochromocytoma in adults and neuroblastoma in children) Reference: Robbins & Cotran Pathologic Basis of Disease, 9edition
5-hydroxyindoleacetic acid (5-HIAA)
Aminolevulinic acid (ALA)
N-formiminoglutamate (FIGlu)
Vanillylmandelic acid (VMA)
miscellaneous