Blood Test: What It Is, How It Is Performed, and How to Prepare

This is a laboratory test that uses a small sample of your blood to measure important substances, such as blood cells, chemicals, proteins, or hormones. Your healthcare provider may order it to check your overall health, find the cause of symptoms, screen for certain medical conditions, or monitor how well a treatment is working over time.

The Stool Ammonia test measures the amount of ammonia present in your stool. Ammonia is a compound produced when bacteria break down proteins in your intestines. Normally, bacteria in your gut help with digestion, but an overgrowth of certain bacteria can produce excess ammonia, which may cause digestive symptoms and indicate underlying health conditions.

A trained healthcare professional will draw a small amount of blood, usually from a vein in your arm or the inside of your elbow. The site is cleaned with an antiseptic, an elastic band is placed around your upper arm, and a sterile needle is used to collect the sample into a tube. The process typically takes only a few minutes, and the sample is then sent to a laboratory for analysis.

You will be given a sterile collection container for your stool sample. Simply collect a small amount of stool (typically about the size of a walnut) in a clean, dry container. Avoid mixing urine or water with the sample. Label the container with your name and date, and deliver it to the laboratory as instructed, preferably within a few hours of collection.

Preparation depends on the specific test your provider has ordered. Some tests require fasting for 8 to 12 hours beforehand, so you may be asked to avoid all food and drinks except water. Others need no special preparation. Tell your provider about all medications, vitamins, and supplements you take, because some can affect the results. Drink water and keep taking your prescription medications unless your provider gives you different instructions.

Generally, no special preparation is required. However, your healthcare provider may ask you to avoid certain medications or supplements before the test, especially antibiotics or probiotics, as these can affect the test results. Follow any specific instructions given by your doctor or the testing facility.