The serum leptin level in non-obese patients with obstructive sleep apnea

Objective: This study aimed to determine the association between the severity of obstructive sleep apnea (OSA) and the serum leptin level in non-obese OSA patients. Methods: This prospective case-control study included non-obese OSA patients that presented with sleep-related disturbances and underwent polysomnography (PSG) between April 2015 and June 2016. The serum leptin level was measured and its relationship to PSG parameters was investigated. Results: The study included 73 OSA patients (20 female and 53 male) with a mean age of 41.1 +/- 11.5 years and mean body -mass index (BMI) of 26.4 +/- 2.7 kg m(-2). The serum leptin level in 44 patients with moderate/severe OSA (AHI >= 15) was 3.4 +/- 2.6 ng mL(-1), versus 4.5 +/- 3.8 ng mL(-1) in 29 patients with snoring/mild OSA (AHI <15) (P = 0.20). There were not any correlations between any of the PSG parameters and the serum leptin level, but there was a significant correlation between the leptin level and BMI (r = 0.345, P < 0.01). Conclusion: The serum leptin level does not differ significantly between non-obese OSA patients with moderate/severe and snoring/mild OSA. Obesity is the primary factor associated with the serum leptin level. (C) 2017 Elsevier B.V. All rights reserved.