interference . measurements - - a direct derivatives and 17 - oxosteroid Anti - arthritic propionic acid

The 24 h urinary excretion of 17-oxo and oxogenic steroids is often used in the investigation of adrenal disease, the 17-oxosteroids reflecting androgen production. The assay involves the formation of a chromogen with 17-oxosteroids by the Zimmerman reaction (Callow et al., 1938). Although a number of drugs are known to interfere with this reaction (Varley et al., 1976; Gray et al., 1969) interference by propionic acid derivatives has not been reported. We report here a patient in whom tiaprofenic acid (Surgam TM), a new anti-arthritic propionic acid derivative, was shown to interfere directly in this reaction.