Study of haemolysis interference limit on serum potassium assay on Roche® Cobas 8000 and evaluation of corrected potassium.

Roche Diagnostics® decided a more restrictive haemolysis index (≤20 HI) for approval the release of serum potassium results. This study examined the risk of overestimating serum potassium results related to the HI according to the Ricos total error (±5.6%) and evaluated the approach of Martinez-Morillo and Alvarez to determine a corrected potassium. According to Ricos' criteria, our study showed compliant potassium results with HI less than or equal to 75. Between 90 and 100 HI, the results did not show a significant overestimation. The equation to obtain Kcorrected was: Kmeasured - (0.004 × HI). The use of corrective formulas for adjusting results of potassium could help the laboratory to identify patients at increased risk and to repeat the test as soon as possible.