Evaluation of serum undercarboxylated osteocalcin in premenopausal rheumatoid arthritis patients: its correlation with disease activity and bone mineral density

Abstract

Background There is a definite role of vitamin K and undercarboxylated osteocalcin (ucOC) on bone mineral density (BMD) in rheumatoid arthritis (RA). Up to our knowledge, no other work has discussed the relationship between ucOC and BMD in premenopausal RA patients and its correlation with disease activity. Patients and methods Sixty premenopausal RA female patients and 30 healthy premenopausal controls of matched age were included. All were subjected to clinical examination, laboratory investigations including serum level of ucOC, disease activity measurement using DAS-28 score, and BMD measurement using dual-energy X-ray absorptiometry. Results The level of ucOC was significantly higher in patients with RA than in controls (P<0.001). BMD in patients was found to be significantly lower compared with controls in the spine, femoral neck, and distal radius areas. The most frequent osteoporotic site according to Z-score was the spine (16.7%), followed by the femoral neck (8.3%) and distal radius (6.7%). The most common commonest osteopenic site according to Z-score was the spine (31.7%), followed by the femoral neck (21.7%) and the distal radius (16.7%). Our work showed that ucOC level was found to be high in premenopausal RA patients with higher DAS values than in those with lower DAS value (P<0.001). In our work, BMD measured by means of dual-energy X-ray absorptiometry scan was found to be lower with higher DAS values and vice versa. Conclusion Serum level of ucOC (which is a mirror of vitamin K deficiency) was found to be higher in premenopausal RA patients than controls and correlated positively with disease activity and inversely with BMD measurement.

Keywords

• disease activity
• osteoporosis
• premenopause
• rheumatoid arthritis
• undercarboxylated osteocalcin