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Published on: May 8, 2021
The influence of vitamin C on the urine dipstick tests in the clinical specimens: a multicenter study
Wonmok Lee1, Yukyung Kim2, Soonhee Chang3
1Department of Laboratory Medicine, Keimyung University School of Medicine, Daegu, Korea.
Background:
Vitamin C may interfere with the results of urine dipstick tests. We investigated the incidence of urinary vitamin C and its interference with urine dipstick reagents using a vitamin C dipstick.
Methods:
The incidence of urinary vitamin C was determined in patients and healthy individuals undergoing routine medical check-ups. Interference tests were performed using samples with various amounts of added vitamin C. For clinical samples, we identified false-negative dipstick glucose, hemoglobin, and leukocyte esterase results based on the urine sediment and serum glucose results.
Results:
Vitamin C was found in the urine of 18.1% of the subjects overall, and 23.1% of those undergoing medical check-ups. Dipstick results for glucose, leukocyte esterase, and hemoglobin differed between samples without vitamin C and with added vitamin C. When vitamin C was detected in clinical urine samples, 42.3%, 10.6%, and 8.2% of the glucose, hemoglobin, and leukocyte esterase dipstick tests were rated as false negative, respectively.
Conclusions:
Vitamin C was frequently found in clinical urine samples, and its concentration was higher in individuals undergoing medical check-ups. Urinary vitamin C can interfere with the urine dipstick results. This study gives useful information for predicting false-negative rates of urine dipstick tests caused by vitamin C.
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