| abstract |
Radiolabelled steroid derivatives having the formula <IMAGE> wherein St is a des-hydroxy steroid moiety of (i) a hydroxy steroid intended for radioimmunoassay or (ii) a hydroxy containing derivative of a steroid intended for radioimmunoassay, said derivative having a strong affinity for the antibodies of the steroid intended for radioimmunoassay; R is hydrogen or alkyl of 1 to 3 carbon atoms; n is 0, 1, 2, 3, or 4 and the asterisk (*) indicates tagging with a radioisotope, are useful as tracers in radioimmunoassays. The unlabelled steroids and precursors thereof are also described. |