Blood ammonia measurement can be used to determine if liver dysfunction is the cause of symptoms such as confusion, drowsiness, coma, or tremor. It can also be used to monitor the effectiveness of treatment for liver diseases, such as cirrhosis.
Ammonia (NH3) is a by-product formed as a result of the breakdown of nitrogen during protein metabolism in the intestine and by the digestion of blood that may be found in the gastrointestinal tract (such as in esophageal varices). Another important source of ammonia is the synthesis and conversion of glutamine from the renal tubules. Normally, ammonia is converted to urea by the liver and then excreted by the kidneys. If any disorder prevents this normal conversion, ammonia accumulates in the blood. Hyperammonemia can also occur in very high intakes of dietary protein.
Toxic levels of ammonia in the blood lead to a condition known as hepatic encephalopathy and high levels of ammonia can affect brain function. The correlation between the level of ammonia in the blood and the degree of encephalopathy may not be proportional. For example, a patient with very high levels of ammonia in the blood may have little or no effect, while in another, brain function may be deeply affected.
What Do Pathological Values Mean?
- Increase: Acute bronchitis, azotemia, cirrhosis, gastrointestinal bleeding, heart failure, neonatal hemolytic disease, hepatic encephalopathy, hepatic insufficiency, leukemia, pericarditis, pulmonary emphysema, renal failure, Reye's syndrome. Medications: heparin, certain diuretics (such as furosemide), acetazolamide, valproic acid.
- Decrease: Idiopathic hypertension, malignant hypertension. Medications: neomycin, tetracycline, diphenhydramine, isocarboxazid, phenelzine, tranylcypromine, lactulose.
Important Note
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.
