Analytic clinical laboratory precision. State of the art for twenty-nine analytes

Relationships of concentration and coefficient of variation are described for 29 clinical laboratory analytes. Estimated mean regression curves and the standard deviations of individual laboratory coefficients of variation about the mean regression are calculated. Twenty-seven analytes showed a significant relation between concentration and coefficient of variation. State of the art precision is compared to medical goals. The average coefficient of variation for one analyte, calcium, fails to meet medical goals for manual methods. The distribution of individual laboratory precision above average state of the art figures is discussed. The proportion of laboratories failing to meet medical goals is large for osmolality, as well as manual calcium methods.