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Test Code NH3 or LAB47 Ammonia, blood

Important Note

Optimally, specimen handling includes placement and transport of specimens on wet ice immediately after collection.  However, specimens are acceptable for up to 30 minutes off of ice.

Within 30 minutes of collection, the specimen must be separated from cells by aliquoting or using a special gel EDTA tube, as described below.

  • If a non-gel EDTA tube,  transfer plasma into the aliquot tube and affix cap.
  • If a Gel (Pearl top) EDTA is used, the plasma may remain in the tube after spinning for up to 2 hours. 

Specimen Requirements

Patient Preparation:

The patient should refrain from smoking or eating for 4-6 hours before sample collection.
Container Type:

Required: Lavender top (EDTA) whole blood

 
Optimal Collection Volume: 

4.5mL; full tube
Minimum Volume:
  • Adults: 1 mL whole blood
  • Neonates: 1 microtainer (400-600 uL)
Collection Instructions:
  1. Draw blood from a stasis-free vein if possible. If tourniquet is used, limit application to less than 1 minute.
  2. Gently invert the sample 5-6 times after collection.
Specimen Transport:

On Ice (see ordering note)
Processing Instructions: 
  1. Centrifuge the specimen as soon as possible. Plasma must be separated from the red cells within 30 minutes of draw (see ordering note for details).

Specimen Stability

Transport Temperature

Stability

Refrigerated - plasma in aliquot tube or spun down in gel tube

2 hours

Frozen - plasma separated from gel tube before freezing

4 weeks

On wet ice - whole blood in non-gel tube

30 minutes

 

*Whole blood in gel tube: Centrifuge immediately. Do not ice the gel tube before centrifugation as gel may not function properly when cold or frozen.

Specimen Rejection Criteria

Hemolysis

Mild OK; Moderate Reject; Gross Reject
Lipemia

Mild OK; Moderate OK; Gross Reject
Icterus

Mild OK; Moderate OK; Gross Reject
Other

Quantity not sufficient

Useful For

Aiding in the diagnosis of various hepatic disorders such as hepatic coma or liver cirrhosis.

 

Investigating and monitoring treatment for inborn errors of metabolism

Methodology

Roche Cobas - Enzymatic kinetic colorimetric assay

Reference Ranges

Age

Reference Range and Reporting Units

Newborn (0 up to 7 days)

54-90 umol/L

Young Infant (7 days to 6 months)

24-48 umol/L

All others >6 months of age

12-48 umol/L

Critical Values:    <6 months of age = >100 umol/L

Note: new critical range for infants only is effective 5/6/2025

Day(s) Performed

24/7

Expected TAT

Same day

Performing Laboratory

Bronson Laboratory, Chemistry - Kalamazoo, Battle Creek, Paw Paw, South Haven

Sample Retention Time

6 days

CPT Code

82140

LOINC Code

16362-6