Plasma 11beta-hydroxy-4-androstene-3,17-dione: comparison of a time-resolved fluoroimmunoassay using a biotinylated tracer with a radioimmunoassay using a tritiated tracer.
The plasma concentration of 11beta-hydroxy-4-androstene-3,17-dione (11beta) is very high in 21-hydroxylase deficiency, Cushing's syndrome, and hyperandrogenism of adrenal origin, and very low in congenital 11-hydroxylase deficiency and adrenal insufficiency. Thus, when plasma 4-androstenedione is elevated, it is useful to measure the plasma 11beta level in order to determine the adrenal or ovarian origin of the hyperandrogenism. To eliminate disadvantages related to the 11beta radioimmunoassay (RIA), which uses a tritiated tracer, as well as the high cost associated with scintillation proximity assay (SPA), we developed a non-isotopic 11beta assay that utilizes an 11beta-biotin conjugate synthesized in our laboratory to measure time-resolved fluorescence after addition of streptavidin-europium to microtitration wells. The analytical qualities of this assay are very similar to those of the radioimmunoassay using a tritiated tracer, and an extraction step followed by celite chromatography (which separates 11beta from interfering plasma steroids) prior to a final radioimmuno-competition step. The correlation coefficient between 11beta levels measured by time-resolved plasma 11beta fluoroimmunoassay (TR-FIA) and RIA was 0.965.Finally, the TR-FIA technique was more sensitive and of greater precision than the RIA method.
Ibrahim
Fidaa
F
Laboratoire d'Hormonologie, Hôpital Saint-Louis, 1, avenue Claude-Vellefaux, 75475 Cedex 10, Paris, France
Giton
Frank
F
Boudou
Philippe
P
Villette
Jean Marie
JM
Julien
René
R
Galons
Hervé
H
Fiet
Jean
J
D000735:Androstenedione / Q000031:analogs & derivatives* / Q000097:blood*; D001710:Biotin / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D005063:Europium / Q000737:chemistry; D005260:Female; D015200:Fluoroimmunoassay / Q000379:methods*; D006801:Humans; D011863:Radioimmunoassay / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019809:Streptavidin / Q000737:chemistry
D000735:Androstenedione; D005063:Europium; C003582:11-hydroxyandrostenedione; D001710:Biotin; D019809:Streptavidin