Detection of anabolic steroids by radioimmunoassay.

The synthetic anabolic steroids have structural features which distinguish them from the natural steroid hormones. It should therefore be possible to detect the taking of these substances by testing for their presence in either blood or urine. At present suitable techniques include gas chromatography, mass spectrometry and radioimmunoassay. For practical and psychological reasons urine tests are preferred although, as with the natural steroid hormones, only a small proportion of the anabolic steroid is excreted unchanged in the urine. A much larger proportion of the steroid usually undergoes minor chemical modification before being conjugated with glucuronic or sulphuric acids and is then excreted in the urine. It is this larger conjugated fraction which is usually used in the gas chromatography and mass spectrometry methods. Because of the great sensitivity of the radioimmunoassay technique we have so far used only the unconjugated steroid.