AB0514 The relationship between serum level of c-terminal telopeptide of type i collagen with course of systemic lupus erythematosus and structural and functional state of bone tissue

Abstract

Background It is well known, that the incidence of osteoporosis in patients with systemic lupus erythematosus (SLE) is higher compared to the population level. Its severity in patients with SLE is associated with a number of factors: female gender, disease activity, damage index, glucocorticoid therapy etc. One of metabolic factors indicating the reducing bone mineral density (BMD) is the level of C-terminal telopeptide of type I collagen (CTX). Its place in the formation of osteoporosis in SLE patients is poorly understood, as well as its relationship with the course of the disease. Objectives The aim of study was to determine serum level of CTX in the SLE patients and its relationship with structural and functional state of bone tissue, course of the disease. Methods The study involved 58 SLE women (study group) and 29 healthy individuals (control group) representative by age and gender. The mean age of patients was 45,11±1,03 years. For every patient data were recorded on age, body mass index (BMI), chronic SLE damage (SLICC/ACR DI) and disease activity score (SLEDAI), cumulative glucocorticoid dose, serum concentrations of interleukin-6 (IL-6) and C-reactive protein (CRP), bone resorption marker (CTX). Serum concentration of CTX was determined using ELISA test system “Nordic Bioscience Diagnostics A/S”. Changes in BMD of the lumbar spine and proximal hip were determined by Dual-energy X-ray absorptiometry. Results It was established, that in patients with SLE serum level of C-terminal telopeptide of type I collagen was 1,15±0,03 ng/ml, while in the control group – 0,83±0,03 ng/ml, or was higher more than 19,0%. Violation of bone remodeling in patients with SLE was associated with reduced BMD, increased incidence of osteopenia and osteoporosis. Thus, the mean concentration of CTX in patients with osteoporosis was 1,63±0,04 ng/ml, while in patients with normal bone – 1,0±0,03 ng/ml. In SLE patients with osteopenia the level of C-terminal telopeptide of type I collagen was 1,23±0,04 ng/ml (higher more than 23% compared with the control group). Increased CTX practically had no correlation with age, duration of the disease, smoking and BMI. At the same time the serum CTX was associated with chronic SLE damage index (r =0,51), SLEDAI disease activity (r =0,41), concentration of IL-6 (r =0,45) and CRP (r =0,44) Conclusions Alterations of bone metabolism were found in 19% female SLE patients in the form of increasing serum CTX and closely associated with the severity and activity of the disease, high levels of CRP and IL-6 and did not depend on the age, disease duration, smoking and body mass index. Disclosure of Interest None declared