Synonyms
NH3; NH4
Specimen Type
Plasma
Performing Lab
RCHSD Chemistry
Epic ID
LAB47
Lab Test Days
As received
Standard TAT
1 Hour
Stat TAT
1 Hour
Collection Information
Specimen Required
0.6-1 mL Blood
Container Type
Light Green (Lithium Heparin PST)
Collection Instructions
Plasma collected in an EDTA (lavender-top) tube or sodium heparin (green-top) tube are also acceptable. Immediately place collected specimen on ice and deliver to lab. Ammonia levels increase as specimen sits before testing. Placing specimen on ice slows the level from increasing. Avoid capillary draws (fingerstick or heel stick) unless extreme circumstances as these collection techniques increases potential for hemolysis. Ammonia levels increase with hemolysis. Satellite locations must send patient to RCHSD for draw. If physician requests "Free Flowing" draw without tourniquet.
Processing Information - Lab Use Only
Transport Temperature
Refrigerated-OK/Frozen-OK
Specimen Stability
Room Temp: <15 minutes; Refrigerated: 2 Hours; Frozen: 3 Weeks
Rejection Criteria
Serum; Hemolysis; Specimens not collected/kept on ice
Test Volume Required
0.5 mL Plasma
Minimum Test Volume
0.3 mL Plasma
Processing Instructions
Keep specimen on ice. Rapid separation of plasma from blood cells is critical for obtaining reliable results. The standard recommendation is no more than 15 minutes from sample collection to the start of centrifugation. Timing is especially critical for patients with liver disease. Delays exceeding 15 minutes have been shown to increase ammonia concentration. Specimen should be free of bubbles. Remove bubbles with an applicator stick before analysis. Use a new applicator stick for each specimen to prevent cross-contamination. Deliver plasma on ice directly to Chemistry as soon as possible. Communicate specimen arrival to CLS/MLT.
CPT Codes
82140
Revised
9/10/25
Initials
SA