[Influence of commercial soft drinks or green tea intake to occult blood and sugar tests with urinalysis reagent strips].

Consumption of commercial soft drinks or tea has increased in over recent years. In many case, these drinks contains large amount of ascorbic acid as an antioxidant. We examined the influence of ascorbic acid to the result of urine occult blood and sugar tests with urinalysis reagent strips. Three subjects took 3 brands of soft drinks (P, C, B) in 3 different days once in the morning. Other 3 subjects took 4 brands of green tea in 4 different days 4 times in a day. After 2 hours of first administration, urine specimen were collected every hour for 8-10 hours. Constant amount of hemoglobin or sugar was added in urine specimen and the reflectance was measured with AX-4280. As a results, urine ascorbic acid induced false negative results in both occult blood and sugar tests in all groups. These results indicate the necessity of patient education about commercial soft drinks or green tea consumption on the previous night and the day of the urinalysis.