Ammonia
A waste product from breaking down protein, normally converted by the liver into urea and removed. When the liver is failing, ammonia builds up in the blood and affects the brain, causing confusion (hepatic encephalopathy) — the main reason this test is used.
What it measures
Ammonia is produced constantly when the body and gut bacteria break down protein. Normally the liver converts it into urea, which the kidneys excrete, keeping blood ammonia low. Its clinical importance is almost entirely about the brain: when the liver cannot clear ammonia — in advanced liver disease or acute liver failure — it accumulates and is toxic to the brain, causing hepatic encephalopathy, a spectrum from subtle changes in concentration and sleep, through confusion and a characteristic flapping tremor of the hands, to drowsiness and coma. So a raised ammonia with confusion in someone with liver disease supports this diagnosis. It can also be high in rare inherited disorders of the urea cycle (usually diagnosed in babies) and with certain medications. The test has practical pitfalls — the sample must be handled carefully and quickly or the level falsely rises — and, importantly, the ammonia level does not correlate neatly with how confused a person is, so it is interpreted alongside the clinical picture rather than treated as a precise gauge.
What a high value can mean
- Liver failure or advanced liver disease — the main cause; the liver cannot convert ammonia to urea, and it builds up.
- Hepatic encephalopathy — the resulting brain effect (confusion, flapping tremor, drowsiness).
- Inherited urea-cycle disorders — rare, usually in babies.
- Certain medications, gastrointestinal bleeding (protein load), and severe illness.
- Sample handling error — a delayed or warm sample can falsely raise the level.
What a low value can mean
- Normal or low — the expected, reassuring result; a low ammonia is not clinically significant.
When to discuss with a doctor
Ammonia is a targeted test, used mainly to support the diagnosis of hepatic encephalopathy in someone with liver disease who becomes confused, drowsy or develops a flapping tremor — although the diagnosis is largely clinical, and treatment (of the encephalopathy and its triggers, such as infection or constipation) often proceeds on the clinical picture. Because the level does not track neatly with severity and is prone to sample-handling errors, it is interpreted with the whole picture, not as a precise measure. New confusion or drowsiness in a person with liver disease is a reason for prompt medical assessment. Mediora.AI shows ammonia with the liver markers (ALT, AST, albumin, INR) so it is read in the context of liver function; the interpretation belongs with your doctor.