Ammonia, Plasma

Ammonia

Alternate Test Name

NH3

Epic Mnemonic
Sunquest Mnemonic

LAB47
NH3

Category

Chemistry

Methodology

Enzymatic

Test Performance Schedule

Sunday - Saturday

Result Availability

Within 24 hours – STAT upon request

Container

Lavender top (EDTA) tube

Volume

Pref. Vol.: 1.0 mL plasma
Min. Vol.: 0.5 mL plasma

Collection Instructions

• Tube must fill to at least ½ or greater of its vacuum capacity
• Immediately after collection, gently invert tube 5-10 times
• Transport to lab on ice (DO NOT OPEN tube)

• MUST be received by testing site within 15 minutes of collection

If unable to transport to reach lab within 15 minutes

• Promptly centrifuge (MUST be within 30 minutes of collection)

• Immediately transfer plasma to a plastic tube

• Freeze

• Transport to lab on ice

Transportation Instructions

Transport to lab on ice

Stability

• Frozen: 3 weeks

Causes for Rejection

• Not collected in (Lavender top) tube

• Plasma not separated from cells within 30 minutes of collection

• Not frozen

• Hemolysis

Remarks

CPT Codes

82140

Effective/Revised

03/21/2017

Ammonia is generated primarily in the gastrointestinal tract by metabolism of nitrogenous compounds. An excess of ammonia can be toxic to the central nervous system. The Krebs-Henseleit urea cycle provides a means of disposal of ammonia by metabolizing ammonia to urea in the liver.

Hyperammonemia in infants can be caused by inherited deficiencies of the urea cycle enzymes or acquired through acute (as in Reye’s syndrome) or chronic (as in cirrhosis) liver disease. In adults, elevated ammonia levels can aid in diagnosis of liver failure or hepatic encephalopathy from advanced liver diseases such as viral hepatitis or cirrhosis.