Ammonia (NH₃)
LiverNormal range
10–80 µg/dL (lab-specific)
SI: 6–47 µmol/L
☎ When to call
New or worsening confusion in a liver patient — escalate the mentation change immediately, whatever the number says.
What you do
- Grade the mentation, not just the number — asterixis check (flapping hands)
- Anticipate lactulose orders; titrated to 2–3 soft stools/day
- Specimen must go on ice and fast — a warm delayed tube reads falsely high
Causes of HIGH ammonia
Causes of LOW ammonia
Source: Pagana, Mosby's Manual of Diagnostic and Laboratory Tests, 7th ed.Reference only — verify against your facility's policy.
