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Home › Research › Neurotransmitters: 5-HIAA
Neurotransmitters

5-HIAA

Optimal result: 800 – 13000 ug/g creat
By Healthmatters Editorial Team
Peer-reviewed sources

Large quantities of serotonin and 5-HIAA may be produced by some carcinoid tumors. Carcinoid tumors are slow-growing noncancerous or cancerous neuroendocrine masses that can form in the GI tract, especially in the appendix, and in the lungs.

5-HIAA is the primary metabolite of serotonin, a chemical substance (neurotransmitter) that transmits messages between nerve cells. After it is used by the body, serotonin is broken down in the liver, and its metabolites, including 5-HIAA, are excreted in the urine.

5-HIAA is a serotonin metabolite.

5-HIAA is the primary metabolite of serotonin, a chemical substance (neurotransmitter) that transmits messages between nerve cells. After it is used by the body, serotonin is broken down in the liver, and its metabolites, including 5-HIAA, are excreted in the urine.

Ordinarily, only small varying amounts of 5-HIAA are present in the urine.

5-Hydroxyindoleacetic acid (5-HIAA) results are expressed as a ratio to creatinine excretion (mg/g CRT).

Reference ranges (in µg/g Cr):

Ages 15 & Older:

2205 – 11816 (Optimum: 2988 – 5850)

Ages 10 – 14:

3802 – 9879

Ages < 10:

6331 – 18834

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Clinical Sources & References

All our content is backed by peer-reviewed studies, academic research, and trusted medical sources. We’re committed to accuracy and transparency — see our editorial policy for details.

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Written by Healthmatters Editorial Team
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