When is ammonia tested?
Normally, ammonia formed during the breakdown of proteins is converted by the liver into urea and excreted by the kidneys. With severe liver damage - cirrhosis, acute liver failure, portosystemic shunting - this mechanism is disrupted, ammonia accumulates and has a toxic effect on the brain. Hepatic encephalopathy develops: sleep disturbances, confusion, characteristic “popping” tremor, up to coma. The second important indication is in newborns and children with unexplained vomiting, lethargy, seizures and developmental delays: the cause may be hereditary urea cycle disorders, in which early diagnosis saves lives. The sample requires immediate transport to the laboratory in the cold - if delayed, the ammonia level will falsely rise.
Why preparation is so important
The laboratory result is a number, but the correct number can only be obtained if the rules are followed. Eating changes the levels of glucose, lipids and a number of enzymes significantly; physical activity the day before increases CK and AST; smoking affects hormones; time of day is critical for cortisol and testosterone.
Therefore, a “bad analysis” often turns out to be a consequence of impaired preparation, and not an illness, and leads to unnecessary examinations and prescriptions.
General rules for donating blood
- on an empty stomach 8–12 hours, you can drink water
- Eliminate alcohol and intense exercise per day
- no smoking in an hour
- donate blood before physiotherapy, x-rays and massage
- Take medications in advance by agreeing with your doctor
- for hormones in women, take into account the day of the cycle
How to read the result
Reference values depend on the method and equipment of the laboratory, so it is correct to compare results only within the same laboratory. A deviation of a few percent from the normal limit in itself rarely matters - the overall picture and dynamics are important. It is up to the physician to interpret the analysis: an isolated indicator without a clinical context is often misleading.