Relationship between delta checks for selected chemistry tests.

The correlation between delta differences for 20 serum chemistry tests was calculated for 2400 samples from 288 patients. There were 12 pairs of chemistry tests for which correlation coefficients of the delta checks exceeded 0.25; aspartate aminotransferase and alanine aminotransferase had the highest Pearson correlation coefficient, 0.915. The highest negative, indirect, correlation was between the delta checks of bicarbonate and chloride (-0.219). The relationship between delta differences may be used as a quality-control technique to detect analytical errors.