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Item Value
Approval req'd? No
Available Stat? Yes (always run STAT)
Test code NH3
Performed by Parnassus & Mission Bay Chemistry
In House Availability Test available 24 hours per day 7 days per week
Method Spectrophotometric, kinetic (glutamate dehydrogenase)
Collection Instructions Pre-chill tube. Deliver to lab immediately on ice.

NOTE: Ammonia cannot be 'added-on' to a previously tested sample
Container type Light Green top (on ice)
Amount to Collect 2 mL blood
Sample type Heparinized plasma
Preferred volume 1 mL plasma
Min. Volume 0.7 mL plasma
UCSF Rejection Criteria Not delivered on ice
Processing notes Centrifuge tube with stopper in place and run test IMMEDIATELY.

If the test is ordered routine or at Mt. Zion, collect the specimen and centrifuge within 20 minutes. Aliquot and freeze the plasma at -20C immediately and send to Moffitt/Long on next scheduled delivery run.
Units µmol/L
Normal range
< 30 days < 50 µmol/L
≥ 30 days < 35 µmol/L

Note: Reference ranges determined by validating the assay manufacturer's reference range in 24 adult laboratory staff and by adapting the newborn reference range from method number 2 in Soldin et al. Pediatric Reference Intervals, 6th edition, 2007
Synonyms NH3
Stability Specimen stability: 20 minutes.
Turn around times 1 hour
Additional information NOTE: Ammonia cannot be 'added-on' to a previously tested sample

False positive elevations of ammonia can be caused by many factors including use of capillary samples or by delay between sampling and centrifugation (Clinical Biochemistry 40:531-535, 2007).

Newborn reference range adopted from Maranda et al., Clinical Biochemistry 40:531-535, 2007.
CPT coding 82140
LOINC code 22763-7
Last Updated 8/9/2016 2:13:12 PM
Entry Number 49
Lab Procedure Link Click here for Procedure
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