What is Stool Reducing Substance?

This test is used to detect the unabsorbed sugar in the stool of a patient. The test gives an idea regarding the patient’s ability to absorb carbohydrates, nutrients, and other forms of sugar from foods and drinks.

Stool (or fecal) reducing substances are a stool sample test used to diagnose lactose intolerance (and some rare metabolic abnormalities). Lactose intolerance can be caused by a prolonged or severe episode of viral gastroenteritis.

The fecal reducing substances test is performed in a laboratory, on a sample of stool as small as 5 grams. Unfortunately this sample needs to be delivered to the laboratory as soon as possible, preferably within 1 hour. This is because lactose (or other sugars) in the stool will normally be broken down by chemical processes within 2-4 hours after the specimen is produced.

Fecal reducing substances are reported as:
Negative – this is the normal result and means that the body is digesting and absorbing sugars properly
Positive – this means there are substances in the stool that can act as ‘reducing agents’, i.e. there are forms of sugar in the stool that have not been absorbed by the body

Why is Stool Reducing Substance done?

There are various reasons why this test may be needed. It may be prescribed during a regular health checkup or if a doctor suspects toxicity in the body. Usually, this test is needed for people who suffer from either lactose intolerance or newborn intestinal tissue death.

Interpreting Stool Reducing Substance results

Interpretations
For adults and children, the normal range is 0.25 g/dL, while the borderline range is 0.25-0.5 g/dL. Anything above 0.5 g/dL is considered abnormal.

Can the sample be collected at home?

You can collect the stool sample at home, but consult the physician before doing so. The healthcare worker will instruct you on how to go about collecting the sample.