Monoclonal gammopathy may disturb oestradiol measurement in the treatment and monitoring of in-vitro fertilization

A 31 year old woman had her treatment for infertility by in-vitro fertiliza tion (IVF) cancelled because a highly elevated serum concentration of oestr adiol was detected, contrary to the clinical picture and that observed by v aginal ultrasound. The immunoassay for measuring oestradiol had been affect ed by circulating heterophilic antibodies in the form of an elevated immuno globulin (Ig) G-kappa M component. This may often be associated with a haem atological malignancy of lymphoid origin, but this patient had a benign mon oclonal gammopathy, Monoclonal gammopathy has not been described in IVF pat ients previously, nor has monoclonal gammopathy been reported as a cause of erroneously elevated oestradiol concentration. This sort of interference i n oestradiol analysis is probably very rare, but may lead to unnecessary ca ncellation of the treatment. A highly elevated oestradiol that is not in ac cordance with the clinical course may indicate heterophilic antibody interf erence, and the cause should always be investigated.