Abstract1. A radioimmunoassay has been developed for the measurement of 2-methoxyoestrogens in samples of human serum without chromatography after solvent extraction. Antibodies raised against 2-methoxyoestradiol-17\g=b\-hemi-succinyl-BSA served as binding protein and 2-methoxyoestrone -17cmo -[125I]iodohistamine served as 125I-labelled ligand. A specific (little or no cross-reactivities to other oestrogens), sensitive (2.4 \ m=+-\0.9 pg/tube) and precise (6.5% intra-assay; 9.1% inter-assay) assay was obtained by employing this heterologous bridge system. 1 The following trivial names and abbreviations were used 2-methoxyoestrone: 2-methoxy-3-hydroxy-1,3,5(10)oestratrien-17-one, 2-methoxyoestradiol: 2-methoxy-l,3,5(10)-oestratriene-3,l7ß-diol, 2-methoxyoestriol: 2-methoxy-l,3,5(10)-oestratriene-3,16ct,17ß-triol, 2-hydroxyoestrone: 2,3-dihydroxy-l,3,5(10)-oestratrien-17-one, 2-hydroxyoestradiol: l,3,5(10)-oestratriene-2,3,17ß-triol, 2-hydroxyoestriol: 1,3,5( 10)-oestratriene-2,3,16 , 17ßtetrol, oestrone: 3-hydroxy-l,3,5(10)-oestratrien-17-one, oestradiol-17ß: l,3,5(10)-oestratriene-3,17ß-diol, oestriol: l,3,5(10)-oestratriene-3,16a, 17ß-triol, 2-methoxyestrone-17-cmo : 2-methoxyoestrone-17carboxymethoxime : 17-(0-carboxymethyl)-oximino-2methoxy-3-hydroxy-1,3,5( 10)-oestratriene, 2-methoxy-oestradiol-17ß-succinyl-BSA : 2-methoxyl,3,5(10)-oestratriene-3,17ß-diol-17ß-ylhemisuccinate-bovine serum albumin. Dedicated to Professor Dr. med. J. Zander on the occasion ofhb 65th birthday. The following concentrations were found in serum sam¬ ples of healthy subjects (median, range in parentheses): men (19-58 years): < 10.3 (< 10.3-35.5) pg/ml (n = 22); women follicular phase: 46 (18-63) pg/ml (n = 8); luteal phase: 70 (31 -138) pg/ml (n = 8); post-menopausal women: 33 (21 -76) pg/ml (n = 10); pregnant women 11th-16th week: 674 (216-1678) pg/ml (n = 46); 37th-40th week: 3768 (2035-10691) pg/ml (n = 34); newborn cord serum 1608 (575-3095) pg/ml (n = 41).2-Hydroxyoestrogens and their monomethyl ethers are a major group of oestrogen metabolites in both laboratory animals and humans. Their role in endocrine physiology is still poorly understood. Investigations into the physiological significance of this type of oestrogens require sensitive and speci¬ fic methods for the quantitative determination of these compounds in body fluids and tissues. 2-Hydroxyoestrogens are rapidly metabolized, ini¬ tially in the vascular space (Bates et al. 1977) and from the quantitative point of view predominantly in the liver (Knuppen et al. 1970), by the catechol-O-methyltransferase. Therefore in addition to the measurement of 2-hydroxyoestrogens (Berg et al. 1982) the 2-methoxyoestrogens should be meas¬ ured for a sufficient description of the production and excretion rates of 2-substituted oestrogens.The radioimmunological method described hitherto utilizes tritium labelled radioligands, with high specific radioactivities not yet available com¬ mercially (Emons et al. 1979).

The serum concentration of the tumour marker CA 125 was determined during an inflammatory adnexitis of a young woman of 22 years of age, the measured value being 478 kU/l. After the inflammation had subsided, a malignoma was largely excluded by laparoscopy; the CA 125 value had dropped to 70 kU/l. In a woman of 34 years of age who had an endometriosis that had been identified for the last ten years, as well as an acute suppurative fibrinous peritonitis, the CA 125 value was found to be 205 kU/l. On the fourth postoperative day the value was around 165 kU/l, on the 13th and 26th postoperative day 273 kU/l and 168 kU/l, respectively. There were no signs of an inflammation.