Analytical clinical chemistry precision. State of the art for fourteen analytes

Relationships of concentration and coefficient of variation for 14 clinical chemistry analytes are described. Estimated mean regression curves and standard deviations of individual laboratory coefficients of variation about the mean regression are calculated. Two analytes, calcium and sodium, showed no relationship of concentration to precision. Twelve analytes showed significant relations between concentration and coefficient of variation. State-of-the-art precision is compared with medical goals. The average coefficient of variation for one analyte, calcium, fails to meet medical goals for automated or manual methods. Average precisions for 13 analytes meet medical goals. The distribution of individual laboratory precision above average state-of-the-art figures is discussed. The proportions of laboratories failing to meet medical goals are large for sodium, chloride and glucose, in addition to calcium.