'Pseudohypouricosuria' in alcaptonuria: homogentisic acid interference in the measurement of urinary uric acid with the uricase-peroxidase reaction.
Urinary excretion of uric acid was found to be extremely low in a 58-year-old female patient with alcaptonuria. This was due to interference with the uricase-peroxidase method used, because analysis using high-performance liquid chromatography (HPLC) showed a normal urinary concentration of uric acid. In vitro experiments demonstrated that a high concentration of homogentisic acid in the patient's urine inhibited the peroxidase reaction, possibly due to inhibition of the colour development of 3-methyl-N-ethyl-N-(beta-hydroxyethyl)aniline (MEHA) and 4-aminoantipyrine, via the peroxidase reaction. A homogentisic acid concentration equivalent to that in plasma did not affect the uricase-peroxidase reaction. This result suggests that any assay based on a peroxidase method is affected by a high urinary concentration of homogentisic acid in patients with alcaptonuria.
Moriwaki
Y
Y
Third Department of Internal Medicine, Hyogo College of Medicine, Japan. t-ohk@hyo-med.ac.jp
Yamamoto
T
T
Nasako
Y
Y
Ohata
H
H
Takahashi
S
S
Tsutsumi
Z
Z
Yamakita
J
J
Higashino
K
K
D000474:Alkaptonuria / Q000150:complications / Q000652:urine*; D005260:Female; D006713:Homogentisic Acid / Q000652:urine*; D006801:Humans; D008875:Middle Aged; D009195:Peroxidase / Q000378:metabolism; D014503:Urate Oxidase / Q000378:metabolism; D014527:Uric Acid / Q000652:urine*
D014527:Uric Acid; D009195:Peroxidase; D014503:Urate Oxidase; D006713:Homogentisic Acid