Laboratory: Clinical Biochemistry  (AUTOMATED)
Test Name:
AMMONIA - (P)
Test Code: AMM
Clinical Information:
Normal values are for venous samples.  Arterial values are slightly lower than venous.  Capillary values are higher.

Ammonia is a waste product of protein catabolism; it is potentially toxic to the central nervous system

Test Indications:
1. Urea cycle disorder in infants including inherited deficiencies of urea cycle enzymes, inherited metabolic disorders of organic acids, and
2. Severe liver disease in adults. Please note that plasma ammonia concentrations do not correlate well with the degree of hepatic encephalopathy and elevated ammonia levels alone do not add diagnostic, staging, or prognostic value for patients with hepatic encephalopathy (Reference: Ammonia Levels Do Not Guide Clinical Management of Patients With Hepatic Encephalopathy Caused by Cirrhosis, Haj, Mona MD; Rockey, Don C. MD, The American Journal of Gastroenterology: May 2020 - Volume 115 - Issue 5 - p 723-728)

Patient Preparation Instructions: Patients must not smoke prior to specimen collection.
Collection Devices:
Collect ON ICE and transport to Lab immediately.
Specimen Required:

Specimens should be put on ice immediately after collection, centrifuged at refrigerated temperature within 20 minutes from collection and tested immediately or frozen immediately if being shipped to another testing lab.
 
Proper specimen handling is critical as false increases in ammonia can occur if transport and processing instructions are not followed. Clotting releases large amounts of ammonia so specimens containing clots are unsuitable and must be rejected. Capillary blood: Values are higher than venous plasma so this is not recommended. If capillary collection is necessary: the capillary site should be warmed to produce a good blood flow and cleansed well to ensure no trace of sweat remains. Sample should be collected into 1 microtainer tube (mix well with each drop), placed on ice and sent to the lab immediately.

Separated Plasma Stability: 
Ambient:Not stable
Refrigerated:3 hours
Frozen:1 day
Referral:
Plasma: 2.0 mL
Pediatric Plasma: 0.3 mL

Shipping & Storage:  Plasma must be transferred to an aliquot tube and stored frozen within 20 minutes of collection. Ship on dry ice if transportation is required. See #110-10-05 Serum / Plasma Separation & Transport for shipping instructions
Requisition:
Reference Values:
< 1 wk:                    ≤82 µmol/L

1 wk – 2 wk:            56-92 µmol/L

3 wk – 17 y:            21-50 µmol/L

≥ 18 y Female:       11-51 µmol/L

≥ 18 y Male:           16-60 µmol/L
Availability:
Stat or Routine
See Also:
More Information: