A chemiluminescence enzyme immunoassay (CLEIA) for the determination of medroxyprogesterone acetate in human serum.

An enzyme immunoassay with chemiluminescence detection (CLEIA) for measuring serum levels of medroxyprogesterone acetate (MPA), a synthetic progestational agent currently used in fertility control and hormonal cancer, is reported. The polyclonal antiserum was obtained by immunizing rabbits with the synthetized 17-hemisuccinate derivative of medroxyprogesterone (MPS) coupled to serum albumin. This antiserum does not display any cross reactivity with extracted metabolites or with corticosteroid analogs with modifications at positions 11 and 16. The same MPS coupled to alkaline phosphatase is used as tracer. For the chemiluminescent detection system, adamantyl-1,2-dioxetane phosphate is selected as substrate. The typical standard curve ranges from 18.5 to 1182 pg per well and displays a slope factor of 0.74, with an ED50 of 143.8 pg of MPA per well and a minimum detectable and maximal level of 0.83 and 12,400 pg per well respectively. The assay has been validated on spiked serum samples in terms of precision (intra- and interassay coefficient variations of less than 8% and 13%, respectively), and of accuracy (mean recovery 105%). The validation on clinical samples demonstrates a good correlation of MPA serum values obtained both by radioimmunoassay and CLEIA. This specific and sensitive CLEIA, which requires less than 100 microliters of serum sample, appears to be an interesting alternative for the monitoring of serum levels of MPA in humans.