Effects of Denosumab Treatment during Early Pregnancy A Case Report

Fumihiro Isobe, Yukio Nakamura, Mikio Kamimura, Shigeharu Uchiyama and Hiroyuki Kato

Background: Osteoporotic treatment during pregnancy is controversial. Denosumab, a fully human monoclonal antibody against receptor activator of nuclear factor-kB ligand (RANKL), is a potent new bone resorptive inhibitory drug for osteopenic and osteoporotic treatment. There has been no report on the effectiveness or adverse effect after denosumab treatment in a young osteoporotic patient.

Case: We experienced a young lady with osteoporosis due to idiopathic menstrual irregularity. Prior to the therapy, we confirmed that she would not be pregnant during the treatment. Denosumab among numerous drugs after the careful discussion was given who completed delivery without any serious complications for mother or child. We regularly examined the values of bone chemical markers during and after pregnancy, and the bone mineral density (BMD) before treatment and after giving birth. Those values improved at 6 months after an initial denosumab injection.

Conclusion: These results suggest that BMD and bone turnover marker values improved at 6 months after the denosumab unintended administration during early pregnancy in a young woman with osteoporosis. To our knowledge, though contraindicated in pregnancy, this is the first report of its use in pregnancy, though inadvertent. The purpose is to demonstrate a case in which it was used in this context without adverse effect.