Is there a diagnostic test for lactose intolerance?
An easy way of diagnosing it is to put the patient on a lactose-free diet and see what happens to them over the next two to three weeks. Patients record their symptoms and note whether things are better before and after the diet. The other way doctors make this diagnosis is a lactose hydrogen breath test. Patients have nothing to eat or drink after midnight the night before and then come in and take a defined amount of a lactose-containing solution. After the individual drinks the solution the breath hydrogen levels are checked at intervals up to two or three hours. In someone who is lactose intolerant, what happens is the sugar is not broken down and it goes down to the colon, where it’s degraded by bacteria. The same bacteria that cause the symptoms increase the hydrogen level in your intestine, which is then absorbed into the blood, which is then exhaled and gives you a rise in breath hydrogen. And that’s the basis for the lactose breath test. The stool acidity is sometimes checked
