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Test Code LAB2785 Ammonia, Blood Venous

Important Note

NO MICROTAINERS. Read "Notes" under Sample Requirements before collection.

Place specimen in outside pocket of a pre-filled biohazard bag of ice, then put into a separate biohazard bag for transport.

Clinical System Name

Ammonia, Blood Venous

Synonyms

LAB2785

Ammon Ven

Sample Requirements

Specimen:  Whole Blood

Container(s):  Dark Green/Sodium Heparin or Heparinized Syringe

Preferred Vol: A filled, unopened 4.0mL Dark Green/Sodium Heparin
                        1.0 mL in a Heparinized syringe

Minimum Vol: 2.5 mL in an unopened 4.0mL Dark Green/Sodium Heparin
                        0.5 mL in a Heparinized syringe

Note: Place specimen in outside pocket of a pre-filled biohazard bag of ice, then put into a separate biohazard bag for transport.

  • There are not good studies on the use/not of tourniquets.  Recommend following CLSIGP41 guidelines for tourniquet use (no longer than 30-60 s) and to avoid clenching fist.
  • For 4.0 mL Dark Green/Sodium Heparin tubes, less than 1/2 full will be rejected. Do not remove vacutainer top to fill tube. Remove air bubbles from Heparinized Syringe immediately after collection.  A venous sample is preferable unless an arterial line is in place.

Processing Instructions

Reject due to: Insufficient quantity, age of specimen, specimen not transported correctly.

Spin: Y

Aliquot: Y

Storage location:  Core 5 Refrigerator

Notes:  Transfer blood gas syringe contents to a bullet tube; centrifuge for 3 minutes. Method is affected by exposure to red blood cells and hemolysis. Not affected by icterus or lipemia.

 

Off-site collection:  Note on requisition if sample is venous or arterial.  Place specimen in separate bag and then in bag with ice. Centrifuge, remove plasma from cells (within 15 minutes), and freeze plasma ASAP. Keep specimen frozen during transport. Plasma must be removed from red blood cells within 15 minutes for an accurate ammonia result.

Stability

Specimen Type Temperature Time
Whole Blood 2-4 C ≤ 15 min
Plasma RT ≤ 15 min
Plasma 2-4 C

≤ 3 h
Plasma -20 C or -70 C

≤ 24 h

 

Plasma must be removed from red blood cells within 15 minutes for an accurate ammonia level.

Availability

STAT Performed TAT
Y 24/7 1 h

Performing Laboratory

Seattle Children's Laboratory    

Department

Department:  Core Lab Chemistry

Phone Number: 206-987-2617 (Client Services)

CPT Codes

82140

Methodology

Method:  Colorimetric method by Vitros 4600

Analytical Volume:  0.02 mL + 0.03 dead space.

Reference Range

Age uMol/L
0 - 3 d 9 - 107  
3 d - 2 w 9 - 92
2 w- 2 m 9 - 50
2 m - adult   9 - 35

Ranges are established in venous plasma. Arterial plasma values will be lower.

Description

Ammonia is a waste product of protein catabolism that is potentially toxic to the central nervous system. Increased plasma ammonia may be indicative of hepatic encephalopathy, hepatic coma in terminal stages of liver cirrhosis, hepatic failure, acute and subacute liver necrosis, and Reye's syndrome. Hyperammonemia may also be found with increasing dietary protein intake.