Table 5:
Factors that Interfere with Determination of Urinary 5-HIAA
Factors that Produce False-Positive Results
Factors that Produce
False-Negative Results
Foods
Drugs
Drugs
Avocados Acetaminophen Corticotropin
Bananas Acetanilid p-Chlorophenylalanine
Eggplants Caffeine Chlorpromazine
Pineapples Fluorouracil Heparin
Plums Guaifenesin Imipramine
Walnuts Lugol's (iodine) solution Isoniazid
   Melphalan Methenamine mandelate
Mephenesin Methyldopa
Methamphetamine Monoamine oxidase inhibitors
Methocarbamol Phenothiazine
Methysergide maleate Promethazine
Phenacetin 5-HIAA, 5-hydroxyindoleacetic acid
Phenmetrazine   
Reserpine
Adapted from reference 11
Copyright 2004 The Cleveland Clinic Foundation

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