Ammonia, Plasma

Test ID: 

702769

CPT code:

82140

Clinical Use:

Ammonia is elevated in the following conditions: liver disease, urinary tract infection with distention and stasis, Reye syndrome, inborn errors of metabolism including deficiency of enzymes in the urea cycle, HHH syndrome (hyperammonemia-homocitrullinuria, hyperornithinemia), some normal neonates (usually returning to normal in 48 hours), total parenteral nutrition, ureterosigmoidostomy, and sodium valproate therapy.

Specimen Type:

Plasma, frozen

Requested Volume: 

1 mL

Minimum Volume: 

0.5 mL

Container Type: 

Lavender-top (EDTA) tube; EDTA is the only acceptable anticoagulant.

Collection:

Tube must be filled completely and kept tightly stoppered at all times. Mix well. Specimen must be placed on ice immediately. Separate plasma from cells within 15 minutes of collection. Patient should not clench fist.

Storage Instructions:

Freeze. Ammonia is stable for several days at -20°C. Caution: Blood ammonia increases rapidly at room temperature.

Stability Requirements:

Rejection Criteria

Hemolysis which increases plasma ammonia; specimen not received frozen; anticoagulants such as citrate, oxalate, ammonium heparin, or sodium fluoride (may cause spuriously high results); lithium heparin may cause spuriously low results; serum specimen (ammonia values in serum are significantly but variably higher than their corresponding plasma values, as ammonia may be generated during clotting); lipemia.