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Test Code Billings Clinic: 4066 Ammonia, Plasma

Important Note

This test can not be added on to a specimen that is already in the lab.  A new sample must be drawn.

Venipuncture should occur prior to Sulfapyridine administration due to the potential for falsely depressed results.

Venipuncture should occur prior to Sulfasalazine administration due to the potential for falsely elevated results.

Performing Laboratory

Billings Clinic Laboratory: Chemistry

Useful For

  • Excess ammonia levels can have a toxic effect on the central nervous system and clinical manifestations are typically neurological disturbances. 
  • Elevated ammonia may also be observed in severe liver failure, as may occur in Reye's Syndrome, viral hepatitis or cirrhosis. 
  • Hyperammonemia occurs with genetic defects of the urea cycle and some other hereditary disorders.

Methodology

Glutamate Dehydrogenase

Specimen Requirements

Refrigerated specimen must arrive within 20 minutes of draw.

  • Draw a FULL, green-top (lithium heparin) tube, NO GEL.
  • Place specimen on wet ice immediately after draw.
  • Spin down and send 2.5 mL of heparinized plasma refrigerated.
  • Forward promptly.
  • If there is a delay in transport of ≥20 minutes, spin down in a refrigerated centrifuge, separate plasma from cells, and send specimen refrigerated in a plastic vial.

DO NOT FREEZE

Storage/Stability

Specimen Type Temperature Time
Plasma Refrigerated 2 hours

 

Reject Due To

  • Hemolysis
  • Gross icterus
  • Specimens received frozen or at room temperature
  • Specimens collected in a gel tube
  • Light blue-top [3.2% sodium citrate] tube, lavender-top [EDTA] tube, or grey-top [potassium oxalate/sodium fluoride] tube is not acceptable.

Reference Values

0 - 1 day                         64 - 107 µmol/L

2 - 14 days                     56 - 92 µmol/L

14 days - 17 years         21 - 50 µmol/L

>17 years                      11 - 32 µmol/L

Day(s) Test Set Up

Daily

Test Classification and CPT Coding

82140 - Ammonia

LOINC Code Information

Reporting Name LOINC Code
Ammonia, Blood 22763-7