Effect of some commonly prescribed drugs on certain chemistry tests

Of the 44 commonly prescribed drugs listed only ascorbic acid, at the upper end of its therapeutic range, significantly affected any (glucose, uric acid) of the twenty-three more frequently requested tests measured in the clinical chemistry laboratory. Acetaminophen, acetylsalicylic acid, ascorbic acid, nitrofurantoin, methyldopa and tetracycline at five times the upper end of their therapeutic ranges individually produced consistently significant effects on one or more of the following tests: glucose, bilirubin, carbon dioxide, calcium, cholesterol, uric acid and aspartate aminotransferase. When drugs are added to lyophilized human serum and to fresh human serum in similar concentrations, their effects on clinical chemistry tests performed on these two different sera are not always the same.