Serum undercarboxylated osteocalcin level increases with 48 weeks of teriparatide treatment in pre-treated elderly rheumatoid arthritis patients who use anti-resorptive drugs.

The serum undercarboxylated osteocalcin (ucOC) level, a biochemical bone marker of vitamin K insufficiency, is often affected by anti-osteoporosis drugs. There have been no reports regarding the relationship between ucOC and teriparatide. We conducted a prospective observational study of 26 female rheumatoid arthritis (RA) patients. The patients were divided into 3 groups: those who underwent a direct switch from anti-resorptive drugs to teriparatide (12 cases), those who started teriparatide without pre-treatment (5 cases), and the control patients (9 cases). The median age (interquartile range) of the patients in each group was 75 (67-77), 82 (78-84), and 69 (62-80) yr, respectively. All patients, except controls, received 48-week treatments of teriparatide. We analyzed the median 48-week changes from baseline of the serum ucOC levels with the Steel-Dwass method. The median change from baseline in the direct switch group was higher than that in other groups (p<0.05). The serum ucOC levels increased with treatment of teriparatide in elderly RA patients, especially when the patients received pre-treatment.