Adjustment of lactate dehydrogenase concentration results according to the haemolysis index following in vitro haemolysis.

In the presence of haemolysis, the interpretation of the Lactate dehydrogenase (LDH) activity result is a major operational challenge for medical laboratories: if the origin is intravascular, then the measurement will reflect the clinical reality, but in extravascular haemolysis, the laboratory will be confronted with an artefactual increase leading to false-positive high results. The aim of our study was to evaluate the adjustment of LDH concentration results according to the haemolysis index (HI). After designed a mathematical model to correct the LDH measured as a function of the haemolysis index using a Cobas 8000 analyser (Roche diagnostics, Mannheim, Germany), LDH measurement of seventy-four duplicate samples were tested before and after exposure to extravascular haemolysis process. After in vitro haemolysis process, a significant increase haemolysis index (Man-Whitney U-Test p < 0.0001) were observed. Before process the HI median was 4 [2.0 - 6.75] and after HI median was 18 [10 - 35.75]. Without correction, LDH results showed a significant increase (p < 0.001) after haemolysis process and substantial analytical discrepancies (31/74) were observed according to TEa of CLIA. After correction, data showed no significant difference (p = 0.497) and the mathematical algorithm allowed to reduce the analytical discrepancies (2/74). If haemolysis was present in vitro, the mathematical algorithm increased the accuracy of the LDH results. However, the lack of discrimination between in vivo and in vitro haemolysis requires caution and the results should be reported only as a commentary to inform the clinician.