Important Information to Know During Our Campus Transformation — Read More
Search All

Lab Test Dictionary



NH3; NH4

Specimen Type


Performing Lab

RCHSD Chemistry

Epic ID


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 is also acceptable. Place collected specimen on ice and deliver to lab immediately after collection. Ammonia levels increase as specimen sits before testing. Placing specimen on ice slows the level from increasing. Avoid capillary draws (fingerstick or heelstick) 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


Specimen Stability

Room Temp: <15 minutes; Refrigerated=2 Hours; Frozen=3 Weeks

Rejection Criteria

Serum; Hemolysis

Test Volume Required

0.5 mL Plasma

Minimum Test Volume

0.3 mL plasma

Processing Instructions

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 directly to Chemistry as soon as possible. Communicate specimen arrival to CLS/MLT.

CPT Codes