Laboratory Services

Ammonia, Plasma

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Updated Test Information:

Test Description
Ammonia, Plasma

NH3 (Ammonia), Plasma

Test ID
General Information

Useful for:

  • Assisting in the diagnosis of hepatic coma

  • Investigating and monitoring treatment for inborn errors of metabolism

  • Evaluating patients with advanced liver disease

Specimen Type

EDTA Plasma

Specimen Requirements


Specimen Collection / Processing Instructions

  • Specimens should be put on ice immediately after collection

  • Centrifuge at refrigerated temperature (4 degrees C)

  • Aliquot plasma into plastic screw-top tube. Keep on ice

  • Freeze plasma within 2 hours of draw.

Minimum Sample Volume

0.50 mL

Additional Processing Details

  • Plasma must be separated from cells and frozen within 2 hours of collection

  • Freeze plasma on dry ice or in a freezer (-60 to -80 degrees C) for long-term storage or shipment.


  • Frozen (preferred): 7 days

  • Refrigerated: 2 hours

Unacceptable Specimen Conditions

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.


  • Specimens should be put on ice immediately after collection, centrifuged at refrigerated temperature, and plasma kept on ice until analyzed

  • Proper specimen handling is critical; false increases in ammonia may occur if transport and processing instructions are not strictly followed


Photometric, Bromophenol Blue (VITROS Dry Slide)

Estimated TAT

1 day

Testing Schedule



1 day

CPT Code(s)


Reference Range

≤ 30 mcmol/L

Performing Lab


LOINC Code(s)


Additional Information