Abstract
Interference of Cyproterone Acetate which is an alkyl substituted steroid used as a drug for anti-androgen was observed on urinary 17-ketosteroids assay. This drug used for patients, sometimes for child, with abnormal high androgen activity is metabolized to 17-keto derivatives and interfer on the 17-ketosteroids assay. Color by Zimmermann reaction from patients urine was orange-brown. and it is impossible to correct the value so that it is prefered to stop the administration of the drug before the test.
