Association between bone remodeling and inflammatory markers in obstructive sleep apnea in relation to disease severity.

INTRODUCTION    There is growing evidence that obstructive sleep apnea (OSA) influences both bone metabolism and structure. Chitinase‑3‑like protein 1 (YKL‑40) is a novel inflammatory and remodeling marker, the levels of which were shown to increase in OSA. YKL‑40 can probably alter the bone turnover. OBJECTIVES    The aim of the study was to assess a possible interplay between YKL‑40 and bone turnover markers in patients with different stages of OSA, and to evaluate the relation between bone mass, severity of OSA, and YKL‑40 levels. PATIENTS AND METHODS    The study involved 72 male patients with OSA. They were divided into 3 groups according to disease severity, using the apnea-hypopnea index (AHI): group 1 (n = 18; 5≤ AHI <15), group 2 (n = 25; 15≤ AHI <30), and group 3 (n = 29; AHI ≥30). All patients underwent polysomnography and densitometry. Fasting blood samples were collected for YKL‑40, C‑terminal telopeptide of typeI collagen (CTX), procollagen type 1 N‑terminal propeptide (P1NP), and other markers. RESULTS    P1NP differed between groups 1 and 2, as well as groups 1 and 3 (P = 0.02). Group 2 had higher CTX levels than group 1 (borderline significance, P = 0.05). A simple linear regression analysis showed that serum YKL‑40 levels were associated with the levels of CTX (P <0.0001, β = 0.9871) and P1NP (P <0.0001, β = 0.9780). CONCLUSIONS    Our study might suggest that YKL‑40 is associated with bone turnover in OSA. We may assume that this marker influences both bone formation and destruction; thus, OSA could be characterized by preserved bone mineral density.