Determination of serum bone-related minerals during denosumab treatment in osteoporosis patients with rheumatoid arthritis: Mineral change by denosumab in osteoporosis with rheumatoid arthritis.

OBJECTIVES

This study included 51 osteoporosis patients with rheumatoid arthritis (RA) who were treated with anti-resorption drug, denosumab. To date, there has been no report on the changes of bone-related minerals after anti-resorption drug therapy.

METHODS

Fifty one osteoporotic patients with RA were retrospectively enrolled. Serum Zinc (Zn), Magnesium (Mg), Iron (Fe), and Copper (Cu) were examined at 1 week, 1, 2, 4, 6, 8, 10, 12 months. Lumbar spine (L1-4) bone mineral density (L-BMD), and bilateral total hip BMD (H-BMD) were examined before and at 6 and 12 months after treatment commencement.

RESULTS

Serum Fe gradually increased except at 4 and 10 months, and significantly increased at 12 months. Serum Mg slightly decreased at 1 week and 1 month, then increased up to 4 months, then gradually decreased to 8 months, then increased thereafter. Serum Zn significantly increased at every time point except at 1 week during the period. Serum Cu increased during the period but slightly decreased at 2, 8, and 12 months. L-BMD as well as H-BMD significantly increased at 12 months (5.1% and 5.1%, respectively).

CONCLUSIONS

Denosumab might be a good option to improve bone-related minerals in OP patients with RA even without dietary supplement. Serum Fe and Mg values became approximately within normal range after the therapy. On the other hand, serum Zn significantly increased for 12 months, however, the Zn values showed still low status after the treatment. Thus, Zn supplementation and/or nutrition education are basically required for OP patients with RA, even though denosumab increases serum Zn level.