Oxygen regulated protein 150 can be considered as a severity indicator in obstructive sleep apnea.

Oxygen-regulated protein 150 (ORP150) is a chaperone found in the endoplasmic reticulum (ER) induced by ER stress, oxidative stress, glutamate toxicity, ischemia, and hypoxia. Increased expression of ORP150 protects the cells by stopping ER stress, maintaining calcium balance, and delaying apoptosis. In this study, we aim to investigate serum ORP150 amount in patients with different severity levels of obstructive sleep apnea (OSA). Forty-nine patients (25 of severe and 24 of mild-moderate), and 23 healthy controls were included in the study. Routine biochemical measurements and serum ORP150 measurements of all groups and sleep quality measurements of OSA groups were obtained. ELISA was used to measure ORP150 levels in serum samples. In addition, ROC analysis was performed to determine the diagnostic power of the ORP150 parameter. There are significant differences between all three groups in terms of ORP150 values (severe OSA: 8.03 ± 0.4 ng/mL; mild-moderate OSA: 5.54 ± 0.47 ng/mL; control: 4.41 ± 0.25 ng/mL, p < 0.017). The highest ORP150 level belongs to the severe OSA group and there is a direct correlation between the severity of the disease and ORP150 levels. ORP150 value is a distinguishing parameter for OSA and the cut-off value of ORP150 was observed as 7.14 ng/mL. We concluded that serum ORP150 levels can be a differential diagnostic parameter in OSA patients and that disease severity can be determined by serum ORP150 measurement.