Ammonia Level

An ammonia level measures the amount of ammonia circulating in your blood. Ammonia is a natural byproduct formed when your body breaks down protein. A healthy liver converts ammonia into urea, which is then removed by the kidneys. When the liver cannot process ammonia efficiently, it can build up in the bloodstream.

This test is usually performed on a plasma sample taken from a vein. Because the result can be affected by how the specimen is handled, the sample is typically kept cold and processed quickly. Your care team interprets this test alongside your symptoms and other labs that assess liver function and overall metabolism.

Ammonia can affect how the brain works. When levels rise, people may experience confusion, sleepiness, irritability, or behavior changes. Clinicians often order this test when there are signs of liver problems, concern for hepatic encephalopathy, or when a newborn or child may have an inborn issue with processing nitrogen waste known as a urea cycle disorder.

Ammonia testing can also help guide care during flares of chronic liver disease, in unexplained vomiting or altered mental status, and when certain medicines might be contributing to symptoms. Knowing your level helps your team decide on next steps, which may include treating the underlying cause, adjusting medications, providing nutrition support, or repeating the test if collection issues are suspected.

Your result is interpreted with your age, symptoms, physical exam, and other tests such as liver function panels and acid base measures. Because collection and handling can influence ammonia, an unexpected result is sometimes repeated to confirm it before making decisions.

If your level is higher than expected, your clinician may look for causes such as liver injury, a urea cycle disorder, bleeding into the gut, infection, dehydration, or medication effects. If your level appears appropriate for your situation, your symptoms may be due to other conditions. Your care team will discuss whether additional testing or treatment is needed and how urgently to act based on your overall clinical picture.