Short-Term Effects of TNF Inhibitors on Bone Turnover Markers and Bone Mineral Density in Rheumatoid Arthritis

TNFa inhibitors (TNFaI) exert positive effectson disease activity in rheumatoid arthritis (RA). Boneinvolvement is a major determinant of functional impairmentin this disease. Here we investigated the short-termeffects of TNFaI therapy on bone metabolism and density.We studied 54 patients with RA starting a TNFaI biologicdrug, in whom any factor known to interfere with bonemetabolism was excluded or rigorously accounted for. Wemeasured at baseline and after 6-month therapy boneturnover markers: N-propeptide of type I collagen (P1NP),and bone alkaline phosphates for bone formation andserum C-terminal telopeptide of type I collagen (CTX) forbone resorption. We also evaluated bone mineral density(BMD) at hip and lumbar by dual-energy X-ray absorptiometry.All bone markers rose significantly and thesechanges were not dependent on steroid dosage. A significantdecrease in femoral neck BMD was also observed.These results indicate that TNFaI therapy in RA over6 months is associated with an early increase in boneturnover and a decline in hip BMD.