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Test Code COHB Carboxyhaemoglobin, Blood

Important Note

Therapeutic levels (1 mg/mL and 2 mg/mL) of Hydroxocobalamin may interfere with COHB assay. Do not expose specimen to air. Specimen should be completely without air bubbles. Mix sample well to prevent clotting. Chill specimen and send to laboratory immediately.

Laboratory Code

LAB56

Specimen Requirements

Submit only one of the following:

 

Preferred

Specimen Type: Whole Blood
Container/Tube: Heparinised Syringe 
Volume: 3.0 mL 
Minimum Volume: 1.0 mL 
Collection Instructions: Collect sample in heparinized syringe and mix well to prevent clotting. Send sample on ice to laboratory immediately.

 

Acceptable:

Specimen Type: Whole Blood
Container/Tube: Capillary Tube (Blood Gas)
Volume: 180.0 uL
Minimum Volume: 180.0 uL
Collection Instructions: Mix well to prevent clotting. Send sample on ice to laboratory immediately (to arrive within 5 mins).

Specimen Stability

Specimen Type Whole Blood
Ambient Reject
Refrigerate 5 mins (ice slurry)
Frozen Reject

Methodology

CO-oximetry

Days and Times Performed

24 hrs, TAT 1 day

Specimen Condition

Haemolysis Not applicable
Icterus Not applicable
Lipaemia Not applicable
Others: Sample not sent in ice, sample not sealed, bubbles present in sample, clotted sample   Reject 

Reference Interval

Potentially toxic: > 15.0%

Testing Laboratory

National University Hospital

Clinical Chemistry, 67724346

Useful For

Diagnosis of carboxyhemoglobinemia.

Service Code

31005

LOINC Code Information

2030-5

Update

Last updated 10/03/2025