return to B index

return to index page

  PTD - 176

Test Directory -  Bicarbonate


TC02, Total C02, HC03

Clinical Indications

Investigation of acidosis/alkalosis.

Request Form

Combined Pathology Blood form (Yellow/Black)


On request. 

Patient Preparation

None required



Please note that this test cannot be added on to existing specimens as uncapped samples lose bicarbonate to air.

Turnaround Time

Same day




2 ml


Green top (lithium-heparin) tube or

Paediatric orange top (lithium-heparin)

A separate green top (lithium-heparin) tube must be taken for adults and samples must be transported to the laboratory within 4 hours of collection

Causes for Rejection

Unlabelled sample.

Reference Range

Serum Bicarbonate: 22 - 29 mmol/L

Reference: Pathology Harmony Group, Clinical Biochemistry Outcomes, January 2011 (www.


Decreased in metabolic acidosis (e.g. DKA) and respiratory alkalosis (overbreathing). Raised in compensated respiratory acidosis and metabolic alkalosis.

Lab Handling


Processing: Test code BIC. Centrifuge and store at 4C in separating fridge (CB39) before processing on primary sample. NOBIC if no sample received or requested as an add-on.

Version 1.2 / February 2015                                                                                                         Approved by: Consultant Biochemist