Specimen Collection

The tube must be filled with minimum air space above sample (at least 80% full).

Sample stability:

• 4 hours at 15-25 ^o C
• 7 days at 4-8 ^o C
• 6months at -20 ^o C

4.5 mL PST Blood (Preferred)

5 mL Heparin Blood

4 mL Plain Serum

3.5 mL SST Blood

1 mL Paediatric Micro-PST Blood
Reference Intervals

Units : mmol/L

Reference range:

Age	Bicarbonate
<2 years	17 - 27
2 years and older	22 - 31

Uncertainty of Measurement : 10%

Turnaround Time: Within 3 hours
Assay Method

Principle: Colorimetric

Reagents: Roche Bicarbonate (CO2-L) kit

Analyser: Cobas c502

Diagnostic Use and Interpretation

Bicarbonate is increased in metabolic alkalosis and compensated respiratory acidosis, and decreased in metabolic acidosis and compensated respiratory alkalosis.

The bicarbonate concentration in plasma is subject to loss of CO ₂ into the air space in the tube, and metabolism by the red blood cells producing lactic acid. For these reasons, bicarbonate values from blood collected into plain or heparin tubes must be regarded as approximate.

For accurate bicarbonate measurement, blood must be taken anaerobically into a heparin syringe and a blood gas requested. See Acid-base.

Contact Information

The chemical pathology team can be reached via email: chemicalpathologist@adhb.govt.nz or via Lablink (09) 307 4949 ext 22000 or 09-3078995

Emails will receive priority attention from the on-call chemical pathologist. Include the patients NHI.

After-hours: contact Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours .

• Dr Samarina Musaad (Clinical Lead) : SamarinaM@adhb.govt.nz ext. 22402
• Dr Cam Kyle : CampbellK@adhb.govt.nz ext 22052
• Dr Weldon Chiu : WeldonC@adhb.govt.nz ext. 23427
• Dr Campbell Heron : CHeron@adhb.govt.nz ext. 23427
• Dr Sakunthala Jayasinghe Saku.Jayasinghe@adhb.govt.nz
• Dr Owen Yi WenyiYi@adhb.govt.nz

Last updated at 11:42:03 16/01/2026