Aim: In this study, we aimed to evaluate the analytical process performance of clinical biochemistry parameters by six sigma method and to make the necessary arrangements according to the obtained results in our laboratory.

Material and Methods: In this study, the process sigma levels of 17 biochemistry parameters in August, September and October 2018 were calculated according to the formula (TEa%-Bias%)/CV%. Bias values were obtained from external quality control reports (KBUDEK), CV% values were acquired from two levels of internal quality control (IQC) samples. Acceptable total error (TEa) ratios determined by CLIA were used for this formula.

Results: Sigma values for glucose in both levels, level-1 of total protein, level-2 of amylase were <3. Sigma values for albumin, chloride, cholesterol and creatinine in both levels and level-1 of HDL cholesterol, level-2 of ALT (Alanine Aminotransferase), total protein and triglyceride were between 3- 3.99. Sigma values for AST(Aspartate Aminotransferase), iron, urea, uric acid in both levels, level-1 of ALT, amylase and triglyceride, level-2 of HDL cholesterol found between 4-5.99. The sigma values for level-2 of total protein, ALT and AST found between 4-5.99. The sigma values for ALP (Alkaline Phosphatase), CK (Creatine Kinase) and LDH (Lactate Dehydrogenase) in both levels were > 6.

Conclusion: Six sigma method allow self-assessment to guide the laboratory's quality control management. In our study, it was concluded that the costs and time loss could be reduced by implementing the Westgard 13S rule especially for the parameters with sigma levels higher than six.