Ammonia
Label Mnemonic: PNH3
Epic code: LAB47
Downtime form: A-1a Doctor/Provider Orders - Pathology Core and Specialty Care Nursery
Chemistry
6240 RCP
356-3527
Specimen(s):
Plasma
Collection Medium:
Lavender top tube 3 mL (EDTA)
Alternate Collection Media:
Heelstick specimens are highly discouraged due to risk of artifactually elevated ammonia levels. or Call laboratory for additional acceptable specimen collection containers.
Minimum:
Full 3 mL lavender top (EDTA) tube or ONE lavender top (EDTA) microtube for pediatric patients.
Rejection Criteria:
Syringe is not acceptable.
Delivery Instructions:
Mix well and place on wet ice. Keep on ice and deliver to laboratory immediately.
Testing Schedule:
24 hrs/day, 7 days a week, including holidays.
Turn Around Time:
1 hour (upon receipt in laboratory)
Reference Range:
Birth to 48 hours old: 64-107 μmol/L
2 days old to 30 days old: 56-92 μmol/L
1 month to 18 years: 21-50 μmol/L

Male: 11-51 μmol/L
Female: 16-60 μmol/L
Clinically significant: >150 μmol/L (<18 years old only)
Comments:
This test is also performed in the Iowa River Landing (IRL) clinical laboratory (for specimens drawn at that site).
Test Limitations:
Criterion: recovery within plus or minus 10% of initial values

Icterus: No interference up to an I index of 30 (approximate 
conjugated 
and unconjugated bilirubin concentration: 30 mg/dL).

Hemolysis: No interference up to an H index of 200 (approximate 
hemoglobin concentration: 200 mg/dL).

Lipemia (Intralipid): No interference up to an L index of 150.  There 
is poor correlation between turbidity and triglycerides 
concentration. 
Absorbance flagging may also be observed as a result of an absorbance 
increase.
Methodology:
Enzymatic
CPT Code:
82140
 
See Additional Information:
Specimens Requiring Immediate Delivery