Test Name


Specimen Type & Acceptability

5 days refrigerated
(CO2 is only acceptable for 5 days if it is in an unopened, refrigerated SST)

General Use

Screening for acid-base balance in a patient.

High value can indicate respiratory acidosis with CO2 retention, or metabolic alkalosis (eg, prolonged vomiting).

Low value may indicate respiratory alkalosis as in hyperventilation or metabolic acidosis (eg, diabetes with ketoacidosis).

CPT Code(s)


Special Instructions

Let clot for 10-20 minutes. After the sample is fully clotted, centrifuge the sample. Verify complete separation between cells and serum. DO NOT OPEN TUBE and refrigerate.

Container/Tube Type


0.5 mL Min. vol. = 100 ul

Suggested Tube Types


Typical Volume

Gold Top Serum Separator Tube (SST)

⋜ 5 mL

Tiger Top Serum Separator Tube (SST)
^For larger volume tests

> 5 mL

Red Top Tube (No additive)

⋜ 5 mL

EDTA Whole Blood

3 mL

3.2 % Sodium Citrate Whole Blood

2.7 mL

Lithium Heparin Plasma Separator Tube

⋜ 5 mL