Urine for Reducing Substances Test

For more than 50 years the detection of reducing substances in urine has been a standard laboratory procedure. For the inborn errors of carbohydrate metabolism, it is used as a screening test. Specifically for screening galactosaemia (galactosuria), this test is performed. A combination of enzymatic dipstick assay for urinary glucose can detect inborn errors of sugar metabolism in pediatric patients. A negative dipstick glucose assay and a positive reducing test suggest that some other substances other than glucose are also present in the urine.

The first urine of the day is required for the sample. It is a microbiology Home-to-Lab urine test. For collecting the urine sample, an easy to use kit is given by the laboratory assistant. No such special preparations are required prior giving the test. If you are taking some medications on daily basis, then it a must to inform the physician/doctor about it. The doctor would suggest you out some instructions that need to be followed. Only on the specific order given by the doctor/ physician this test is performed.

The results may take 1-2 days. If the test results are shown positive, then paper chromatography for sugars and amino acids are performed on the given sample. The paper chromatography is used for the identification of specific reducing sugar and amino acids present in the urine. In most of the positive cases, reducing substance is lactose or sugar. While, if the test results are negative, then it signifies no reducing substance found in the urine. It has been found that persons having positive result test follows a very strict and restricted diet i.e. without fruits, vitamin C, honey and drugs.

Minimum 1.0mL urine is required for testing. A plastic urine cup with a cover is required for collecting the urine sample. The samples can be refrigerated if they are not going for immediate testing. A urine transport tube (yellow top and blue fill line) is used for transporting the urine sample. The tube must be filled till 10mL line. As the sample of urine is original without any preservative, therefore deterioration/alteration of chemical constituents may have occurred. Benedict’s Copper Reduction Reaction Methodology is being used for testing.