Time-resolved immunofluorometric assay of 17 beta-hydroxysteroid dehydrogenase in plasma

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 37; no. 8; pp. 1412 - 1415
• Main Authors: Maentausta, O, Menjivar, M, Vihko, R
• Format: Journal Article
• Language: English
• Published: Washington, DC Am Assoc Clin Chem 01.08.1991; American Association for Clinical Chemistry
• Subjects: 17-Hydroxysteroid Dehydrogenases - blood; Adenocarcinoma - enzymology; Adult; Analytical, structural and metabolic biochemistry; Biological and medical sciences; Enzymes and enzyme inhibitors; Female; Fluorescent Antibody Technique; Fundamental and applied biological sciences. Psychology; Humans; Male; Middle Aged; Uterine Neoplasms - enzymology; Menstrual cycle; Immunofluorescence; Enzyme; 20α-Hydroxysteroid dehydrogenase; Blood plasma
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1093/clinchem/37.8.1412

We describe a time-resolved immunofluorometric assay (TR-IFMA) for human 17 beta-hydroxysteroid dehydrogenase (17HSD) in which antibody-coated microtiter strip wells and europium chelate-labeled polyclonal antibodies are used. In preparing the label, a polyclonal antibody is affinity-purified and derivatized with diethylenetriamine-pentaacetic acid. With this derivative, five to eight europium ions can be combined with one antibody molecule without decreasing the antibody's immunoreactivity. The minimum detectable concentration of 17HSD is 0.13 microgram/L; the intra- and interassay CVs are less than 8% and less than 15%, respectively, for concentrations between 0.3 and 100 micrograms/L. There is no difference between the concentrations of 17HSD in plasma specimens taken during the proliferative and luteal phases of the menstrual cycle, the measured mean concentration being 0.22 microgram/L. We found no correlation between plasma 17HSD and progesterone concentrations. The plasma concentrations of 17HSD increase during pregnancy, the mean concentrations being 1.5, 4.4, and 12.5 micrograms/L, during the first, second, and third trimesters of pregnancy, respectively. In the specimens from 18 men, the mean concentration was 0.18 microgram/L. In six plasma specimens from patients with endometrial adenocarcinoma, the mean concentration was 0.20 micrograms/L. Pre-analytical aspects are important in the assay of 17HSD because of the lability of the enzyme protein. Preferably, blood should be sampled into EDTA-containing tubes, plasma should be separated within 15 min, and glycerol must be added without delay to a final volume of 200 mL/L.