Potassium (serum)

Alternative names, keywords

K

Samples required

● Clotted blood (gold cap, 5 mL tube). Smaller tubes are available for paediatric samples.

Avoid haemolysis. Separate within 2 hours if possible, or transport to lab within 4 hours at room temperature avoiding temperature change.

Samples received more than 8 hours after venepuncture are unsuitable for analysis.

Test indications

Bicarbonate on same sample may be useful if hypokalaemic.

Factors affecting test performance/ results

Contamination with erythrocyte contents will elevate results, because the potassium concentration in erythrocytes is 25x higher than in normal plasma. The degree of interference may be variable depending on the content of analyte in the lysed erythrocytes.

For certain types of haematological neoplasias, (severe) pseudohyperkalemia using lithium heparin samples has been reported.

Results should always be assessed in conjunction with the patient’s medical history, clinical examination and other findings.

Reference range

serum: 3.5 - 5.1 mmol/L
plasma: 3.4 - 4.5 mmol/L

_{Source: Roche Cobas^® ISE insert 2022-01, V13.0}

Turnaround time

Same day (within 1h if urgent)

Enquiries

Biochemistry (Automation)