Analysis of leptin levels in patients with axial spondyloarthritis who have impaired bone mineral density

Sytenko A.O.¹, Bortkevych O.P. ²

• ¹State Institution «National Scientific Center «Institute of Cardiology, Clinical and Regenerative Medicine named after Academician M.D. Strazhesko of the National Academy of Medical Sciences of Ukraine», Kyiv
• ²State Institution «National Scientific Center «Institute of Cardiology, Clinical and Regenerative Medicine named after Academician M.D. Strazhesko of the National Academy of Medical Sciences of Ukraine», Kyiv

Summary. Axial spondyloarthritis (AxSpA), limiting the physical activity of patients, is considered a risk factor for weight gain. Adipose tissue is a metabolic organ that produces adipokines, which are associated with the development of bone mineral density disorders and overweight. Leptin is a peptide hormone of adipose tissue (adipokine) that regulates eating behavior and metabolism in bone tissue. The aim. To investigate the association between leptin levels and body weight with the risk of osteoporosis in patients with axial spondyloarthritis (AxSpA) compared to the control group and a group of patients with other rheumatological diseases (psoriatic arthritis, rheumatoid arthritis). Methods. The study involved 56 patients, including 16 women and 40 men. The number of patients with AxSpA was 26, with psoriatic arthritis — 6, with rheumatoid arthritis — 12, the control group consisted of 6 patients without rheumatic disease. BMI, weight, laboratory indicators of activity for ESR and CRP, leptin were analyzed. To assess bone mineral density (BMD), the results of dual-energy X-ray absorptiometry (DRA) were used. The relationship between leptin levels, clinical and laboratory data, as well as DRA results was analyzed. For comparison of groups, nonparametric methods Kruskal — Wallis, Mann — Whitney test were used. To assess the reliability of differences, Pearson’s criterion (Х2) was used. To assess the strength of the association (between leptin levels and weight), regression analysis was performed. ST Statistica software. Results. As a result of the analysis of the association between leptin levels and weight, it was established that in the AxSpA group, each kg of body weight has a smaller amount of leptin than in the control group. In the AxSpA group, 10% (p = 0.25) had OP, the PsA group — 0% (p = 0.25), the RA group 5.9% (p = 0.25), and in the control group 3.8% (p = 0.25). All groups did not significantly differ in the frequency of osteoporosis; leptin levels were not significantly associated with the risk of osteoporosis. Conclusions. Patients with AxSpA have a higher median body weight and a significantly lower median leptin concentration compared to the control group. Compared to the control group, the strength of the association between leptin levels and body weight changes in AxSpA. In patients with AxSpA, the risk of osteoporosis is not associated with leptin levels.