Monoclonal gammopathy may disturb oestradiol measurement in the treatment and monitoring of in-vitro fertilization: case report.

A 31 year old woman had her treatment for infertility by in-vitro fertilization (IVF) cancelled because a highly elevated serum concentration of oestradiol was detected, contrary to the clinical picture and that observed by vaginal ultrasound. The immunoassay for measuring oestradiol had been affected by circulating heterophilic antibodies in the form of an elevated immunoglobulin (Ig) G-kappa M component. This may often be associated with a haematological malignancy of lymphoid origin, but this patient had a benign monoclonal gammopathy. Monoclonal gammopathy has not been described in IVF patients previously, nor has monoclonal gammopathy been reported as a cause of erroneously elevated oestradiol concentration. This sort of interference in oestradiol analysis is probably very rare, but may lead to unnecessary cancellation of the treatment. A highly elevated oestradiol that is not in accordance with the clinical course may indicate heterophilic antibody interference, and the cause should always be investigated.