5-Hydroxyindoleacetic Acid (HIAA), Quantitative, Random Urine (Pediatric)

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Turnaround Time: 4 - 8 days
CPT Code:

83497, 82570

Test Type: 1 mL aliquotUrine (random)
Stability Time:



Room temperature

7 days


14 days


14 days

Freeze/thaw cycles

Stable x3

Reference Range:

Pediatric patients:1

• 0 to 8 years: 0.0−16.2 mg/g creatinine

• 9 to 12 years: 0.0−8.7 mg/g creatinine

• 13 to 17 years: 0.0−5.5 mg/g creatinine

• >17 years: 0.0−6.9 mg/g creatinine

If a borderline elevation of 5-HIAA is found, sample should be recollected following withdrawal of dietary and medication sources that might elevate 5-HIAA (see Patient Preparation). Nontropical sprue may cause a slight increase in urinary 5-HIAA. 5-HIAA levels are lowered by renal insufficiency and after small bowel resection. When a patient strongly suspected for carcinoid syndrome shows normal or borderline increases of 5-HIAA, two possibilities should be considered: one, that large amounts of serotonin produced are not being metabolized, in which case blood levels of serotonin are required to document the diagnosis; and two, that secretion of 5-HIAA by the tumor is intermittent, in which case repeat timed specimen collections are needed to demonstrate the abnormality.


A serotonin analysis is most frequently performed for the diagnosis of carcinoid tumors of the enterochromaffin (Kultschitzsky) cells of the small intestine. These tumor cells release large amounts of serotonin, which can produce the clinical syndrome of flushing, diarrhea, and right-sided heart failure. The most frequently used diagnostic test for carcinoid tumors is 5-HIAA, the final metabolite of serotonin. Diagnose carcinoid tumors and syndrome; values >25 mg/24 hours (higher if the patient has malabsorption) are strong evidence for carcinoid.

5-HIAA may be normal with nonmetastatic carcinoid tumor and may be normal even with the carcinoid syndrome, particularly in subjects without diarrhea. Some patients with the carcinoid syndrome excrete nonhydroxylated indolic acids, not measured as 5-HIAA.2 Midgut carcinoids are most apt to produce the carcinoid syndrome with 5-HIAA elevation. Patients with renal disease may have falsely low 5-HIAA levels in the urine.3 5-HIAA is increased in untreated patients with malabsorption, who have increased urinary tryptophan metabolites. Such patients include those with celiac disease, tropical sprue, Whipple disease, stasis syndrome, and cystic fibrosis. It is increased in those with chronic intestinal obstruction.4 Poor correlation exists between 5-HIAA level and the clinical severity of the carcinoid syndrome.4 Recent studies confirm its use as a prognostic factor in this disease.5

This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration.

1. Soldin SJ, Brugnara C, Gunter KC, eds. Pediatric Reference Ranges. 2nd ed. Washington, DC: AACC Press;1997:89.

2. Johnson HC Jr. Urine tests. In: Berk JE, ed. Bockus Gastroenterology. 4th ed, vol 1. Philadelphia, Pa: WB Saunders Co;1985:342-347.

3. Schultz AL. 5-Hydroxyindoleacetic acid. In: Pesce AJ, Kaplan LA, eds.Methods in Clinical Chemistry. St Louis, Mo: Mosby-Year Book Inc;1987:714-720.

4. Warner RR. Carcinoid tumor. In: Berk JE, ed, Bockus Gastroenterology. 4th ed, vol 3. Philadelphia, Pa: WB Saunders Co; 1985:1874-1876.

5. Agranovich AL, Anderson GH, Manji M, et al. Carcinoid tumour of the gastrointestinal tract: Prognostic factors and disease outcome. J Surg Oncol. 1991; 47(1):45-52. PubMed 1708841

6. Feldman JM. Urinary serotonin in the diagnosis of carcinoid tumors. Clin Chem. 1986; 32(5):840-844. PubMed 2421946

Collection Details:

Patient Preparation:

Avoid bananas, avocados, plums, eggplant, tomatoes, avocados plums, eggplant, tomatoes, plantain, pineapple, walnuts, and interfering drugs for a 72 hour period prior to and during collection. Foods and medications associated with altered urinary HIAA results: Decreased HIAA: Aspirin, chlorpromazine (Thorazine), corticotropin, dihydroxyphenylacetic acid, alcohol, gentisic acid, homogentisic acid, hydrazine derivatives, imipramine (Tofranil®), <isocarboxazid (Marplan), keto acids, levodopa, MAO inhibitors, methenamine methyldopa (Aldomet®), perchlorperazine, phenothiazines (Compazine®), promazine, promethazine (Mepergan®). Increased HIAA: Acetaminophen, acetanilide, caffeine, coumaric acid, diazepam (Valium®), ephedrine, fluorouracil glycerol guaiacolate (Guaifenesin), melphalan (Alkeran®), mephenesin, methamphetamine (Desoxyn), methocarbamol (Robaxin®), naproxen, nicotine, phenacetin, phenmetrazine, phenobarbital, phentolamine, rauwolfia, reserpine.

Collection Instructions:

Plastic urine container, no preservative. (Note: Boric acid may be added as a preservative for other tests without harm to 5-HIAA.)

Screw the lid on securely. Label container with patient's name, date, and time. Mix well; send aliquot.

Room temperature.