NH3
Medical abbreviation · Laboratory Test
| Stands for | Ammonia |
|---|---|
| Categories | Medical |
NH3 stands for Ammonia, a laboratory test abbreviation also used in science.
Blood ammonia, a nitrogen waste product normally converted to urea by the liver, is measured when hepatic encephalopathy, a urea cycle disorder, Reye syndrome or valproate toxicity is suspected. Normal adult values are roughly below 50 micromol/L, and very high levels can cause brain swelling.
Example: NH3 210 in a newborn with vomiting and lethargy; metabolic team called for urea cycle defect.
Usage notes
NH3 is the chemical formula for ammonia. Samples should be drawn without prolonged tourniquet use, placed on ice and analyzed within about 30 minutes, since levels rise in standing blood. Liver society guidelines note that a high ammonia alone does not diagnose or stage hepatic encephalopathy, but a normal value in a confused patient should prompt a search for another cause.
Related abbreviations
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- PaO2 – Partial pressure of arterial oxygen
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This entry is for general education and is not medical advice. Abbreviation use varies between institutions; always confirm in context.