Improved radioimmunoassay of urinary estriol

We report a rapid double-antibody radioimmunoassay for urinary estriol. Advantages over other current methods include: (a) 30-min hydrolysis; (b) total incubation time, 55 min; (c) assay unaffected by urinary glucose; (d) no degradation of estriol evident during hydrolysis; (e) superior (85%) analytical recovery of estriol conjugates; (f) linear standard curve by logit-log extrapolation; (g) good correlation (r = 0.83) with total estrogen determination by a generally accepted colorimetric method; (h) only 20 muL of urine required; and (i) the detection range is 1.9 to 100.5 mg/24-h urine.