Sheetal, 39-yrs-old presents with chronic abdominal cramps, watery
diarrhea, and periodic facial flushing. Examination reveals wheezing and
a slightly enlarged liver. Work up reveals several masses within the
liver and a large mass in the small intestine. Which of the following
substances is likely to be elevated in her urine?
A. 5-HIAA
B. Aminolevulinic acid (ALA)
C. FIGLU
D. Norepinephrine
A. 5-HIAA
B. Aminolevulinic acid (ALA)
C. FIGLU
D. Norepinephrine
Ans. A.
5-hydroxyindoleacetic acid(5-HIAA)
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 virtually always asymptomatic.
· Carcinoid tumors arise from cells of the neuroendocrine system, which, as
part 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 normetanephrineor vanillylmandelic acid (VMA) with
tumors of the adrenal medulla (pheochromocytoma in adults and neuroblastoma in
children).
