Lactose Tolerance Test

Lactose Tolerance Test

What is a lactose tolerance test?

A lactose tolerance test evaluates the body's ability to break down lactose, the sugar found in milk, within the intestines.

What occurs during a lactose tolerance test?

Before the test, the patient refrains from eating or drinking anything for 8 to 12 hours. Following this period, a blood sample is collected from the fingertip to assess the sugar levels in the blood.

Next, the patient ingests a solution containing milk, sugar, and a hint of lemon. If lactose is adequately broken down in the intestines, the blood sugar level should increase within an hour after consuming the solution. Subsequent blood samples are obtained to monitor this response.

If there's no notable rise in blood sugar levels, it suggests that lactose isn't being properly broken down into galactose and glucose. This commonly results from a deficiency in the enzyme lactase, which is responsible for lactose digestion. This condition is known as lactose intolerance.

What are other methods to diagnose lactose intolerance?

Additional tests for diagnosing lactose intolerance include the hydrogen breath test and stool acidity test.

What is the hydrogen breath test?

The patient refrains from consuming food or drink for 8 to 12 hours before the test.

To establish a low baseline breath hydrogen level, patients are advised to avoid high-fiber foods the evening before the test.

A baseline breath sample is collected.

Afterward, the patient drinks a solution containing milk, sugar, and lemon. If lactose is properly digested in the intestines, subsequent breath samples collected at 15 or 30-minute intervals over two hours won't exhibit a significant increase in hydrogen levels.

However, if lactose isn't digested in the intestines, bacteria in the large bowel metabolize it, producing hydrogen gas. This gas is absorbed into the bloodstream and eventually exhaled through the breath, where it can be measured.

While primarily used for diagnosing lactose intolerance, this test may also detect other less common conditions.

A positive result indicates a rise of 20 parts per million of hydrogen above baseline.

What is a stool acidity test?

The stool acidity test is employed to identify lactose intolerance in children.

Unlike lactose tolerance and hydrogen breath tests, which aren't suitable for infants and very young children suspected of having lactose intolerance, the stool acidity test is utilized.

How does the stool acidity test function?

In addition to hydrogen gas, bacteria in the large bowel produce lactic and other acids from lactose, which can be detected in stool samples.

The test measures the acidity of a stool sample passed after ingesting a small amount of lactose.