Diagnosis & Tests:
Several types of tests exist for one to find if suffering from LI. The tests range from simple breath tests to blood, self home tests and stool tests depending on the age of the person. One must be careful and follow all procedures to avoid false positive or negative results.
Diagnosis of Lactose Intolerance
The most common tests used to measure the absorption of lactose in the digestive system are the lactose tolerance test, the hydrogen breath test, and the stool acidity test. These tests are performed on an outpatient basis at a hospital, clinic, or doctor's office. However, one can also perform a home self-test.
Lactose Tolerance Test
The lactose tolerance test begins with the individual fasting (not
eating) before the test and then drinking a liquid that contains lactose.
Several blood samples are taken over a 2-hour period to measure the person's
blood glucose (blood sugar) level, which indicates how well the body is able
to digest lactose.
Normally, when lactose reaches the digestive system, the lactase enzyme breaks it down into glucose and galactose. The liver then changes the galactose into glucose, which enters the bloodstream and raises the person's blood glucose level. If lactose is incompletely broken down, the blood glucose level does not rise and a diagnosis of lactose intolerance is confirmed.
Hydrogen Breath Test
The hydrogen breath test measures the amount of hydrogen in a person's
breath. Normally, very little hydrogen is detectable. However, undigested
lactose in the colon is fermented by bacteria, and various gases, including
hydrogen, are produced. The hydrogen is absorbed from the intestines,
carried through the bloodstream to the lungs, and exhaled. In the test, the
patient drinks a lactose-loaded beverage, and the breath is analyzed at
regular intervals. Raised levels of hydrogen in the breath indicate improper
digestion of lactose. Certain foods, medications, and cigarettes can affect
the accuracy of the test and should be avoided before taking it. This test
is available for children and adults.
Stool Acidity Test
The lactose tolerance and hydrogen breath tests are not given to infants and
very young children who are suspected of having lactose intolerance. A large
lactose load may be dangerous for the very young because they are more prone
to the dehydration that can result from diarrhoea caused by the lactose. If a
baby or young child is experiencing symptoms of lactose intolerance, many
paediatricians simply recommend changing from cow's milk to soy formula and
waiting for symptoms to abate.
If necessary, a stool acidity test, which measures the amount of acid in the stool, may be given to infants and young children. Undigested lactose fermented by bacteria in the colon creates lactic acid and other short-chain fatty acids that can be detected in a stool sample. In addition, glucose may be present in the sample as a result of unabsorbed lactose in the colon.
One can self diagnose for lactose maldigestion by having a milk challenge. A person fasts overnight and then drinks a large glass of milk in the morning. Nothing further is eaten or drunk for 3-5 hours. If a person is lactose intolerant, the milk should produce symptoms. The time the symptoms start vary from one individual to another. They may occur as early as within one hour or can take up to 3 hours within of ingestion. If there are no symptoms, it is unlikely that lactose intolerance is the cause of the symptoms. It is important for the milk that is used to be non-fat milk to eliminate the possibility that fat in the milk is the cause of symptoms.
Warning: It is very important that this test is purely done after understanding the different symptoms between milk allergy and lactose intolerance. They are entirely two different disorders. If not sure visit the page which lists the different symptoms. This is not usually confusing since allergy to milk is rare and usually occurs in infants and young children. However, persons with severe milk allergy may experience an anaphylactic shock! (If milk allergy is a consideration, pure lactose can be used instead of milk.)
An important issue in the milk challenge is the amount of milk to use.
If a person drinks glasses of milk or ingests larger amounts of milk-containing products in their normal diet, then a larger amount of milk should be used in the challenge, equivalent to one or two large glasses of milk.
If the person being tested usually does not drink glasses of milk or ingest larger quantities of milk-containing products, there may be a problem with using large quantities of milk as they may cause symptoms, but the smaller amounts of milk or milk products that these persons ingest in their normal diet may not be enough to cause symptoms. Technically, they may be lactose intolerant when they are tested with larger amounts of milk, but lactose in their normal diet cannot be responsible for their usual symptoms.
Recognition of this issue is important in interpreting the results of a milk challenge.