Abstract
We report two patients with markedly elevated 24-h urine 5-hydroxyindoleacetic acid (5-HIAA) excretion due to over-the-counter (OTC) self-medication with 5-hydroxytryptophan (5-HTP). It is important to recognize that OTC medication may cause increased 'false-positive' 5-HIAA excretion to prevent undue patient anxiety and unnecessary further investigation for carcinoid disease. Discordance between chromogranin A and 24-h urine 5-HIAA results should alert to the possibility of false-positive or -negative laboratory results.
MeSH terms
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5-Hydroxytryptophan / administration & dosage
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5-Hydroxytryptophan / metabolism*
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Aged
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Chromatography, High Pressure Liquid
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Chromogranin A / blood
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False Positive Reactions
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Female
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Humans
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Hydroxyindoleacetic Acid / urine*
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Malignant Carcinoid Syndrome / diagnosis
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Malignant Carcinoid Syndrome / urine
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Middle Aged
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Nonprescription Drugs / administration & dosage
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Nonprescription Drugs / metabolism*
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Serotonin / metabolism
Substances
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Chromogranin A
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Nonprescription Drugs
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Serotonin
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Hydroxyindoleacetic Acid
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5-Hydroxytryptophan