[Negative interference with peroxidase-coupled enzymatic serum creatinine assay by a hemostatic drug containing a...

We report a discrepancy between serum creatinine levels obtained by the method based on alkaline picric acid (Jaffé reaction) and that by automated analyzer employing enzymatic assay based on peroxidase-coupled reaction in a patient with renal dysfunction taking Ethamsylate, a capillary vessel stabilizer. Serum creatinine level obtained by the Jaffé reaction was 83 mg/l, and that by the enzymatic method was 22 mg/l. Recovery test of creatinine using the patient's serum showed 101 to 102% recovery by the Jaffé reaction and 77 to 89% by the enzymatic method. The same results were observed both in an in vitro test and in serum obtained from a healthy volunteer who had been given Ethamsylate previously. As the chemical structure of Ethamsylate includes a hydroquinone unit, it was thought that the compound may consume hydrogen peroxide produced by the reaction of peroxidase as the hydrogen donor and compete with the substrate used as the hydrogen donor for the color development. Thus evaluation of test results obtained by peroxidase coupled methods should be carefully interpreted in a patient who is consuming drugs which hydrogen peroxide such as hydroquinone.