[How reliable are laboratory results? Many factors are to be considered]

Variation in medical laboratory results is predominantly due to biological factors in the patients and differences in sampling and sample handling procedures, factors which are unaffected by quality assurance procedures in the laboratory. Regarding medical diagnostics, physicians are often deficient in their knowledge of optimal analytical alternatives appropriate for different clinical requirements, and of biological and pre-analytical factors characterised by variation. This reduces the efficacy of laboratory diagnostics. Laboratory results are reliable when they are obtained by competent personnel, and reach their optimal diagnostic potential when they are interpreted by experienced and well informed diagnosticians.