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Ammonia

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.

Specimens should be sampled from free flowing blood without the use of tourniquets or heel/finger sticks.

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 Uncentrifuged blood samples that are > 30 minutes old or plasma samples that have not been tested or frozen within 2 hours of preparation.
Processing notes Sample should be transported to the lab on ice immediately after draw and the plasma separation from cells should be completed within less than 30 minutes of the blood draw. Once the plasma sample is obtained, it should be maintained on ice or refrigerated and analyzed immediately.

If the plasma cannot be analyzed immediately, it is stable on ice or in the refrigerator for 2 hours.

Stability information obtained from ARUP

If the test is ordered routine or at Mt. Zion, collect the specimen and centrifuge within 30 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
Critical value >150 µmol/L for patients less than 18 years of age
Synonyms NH3
Stability Sample should be transported to the lab on ice immediately after draw and the plasma separation from cells should be completed within less than 30 minutes of the blood draw. Once the plasma sample is obtained, it should be maintained on ice or refrigerated and analyzed immediately.

If the plasma cannot be analyzed immediately, it is stable on ice or in the refrigerator for 2 hours.

Stability information obtained from ARUP
Turn around times 1 hour
Additional information NOTE: Ammonia cannot be 'added-on' to a previously tested sample

Specimens should be sampled from free flowing blood without the use of tourniquets or heel/finger sticks. 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 10/30/2017 10:11:34 PM
Entry Number 49
Lab Procedure Link Click here for Procedure
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