OBJECTIVECurrently people regard polysomnography (PSG) monitoring as the golden standard for diagnosis of obstructive sleep apnea-hypopnea syndrome (OSAHS) in children. However, due to the high cost, time and manpower consuming, PSG is not applicable to epidemiological investigation and clinical screening, especially not suitable for child patients and remote hospitals in Xinjiang. Therefore, it is of important clinical significance to find out a simple method (e.g. a kind of serum index) to primarily screen out suspicious patients for early diagnosis and treatment. The present study was conducted to assess the clinical usefulness of the measurement of orexin-A concentration in serum as a diagnostic predictor to screen patients with OSAHS in children.

METHODSSerum orexin-A concentration was measured with enzyme immunoassay (EIA) kit in 60 patient with snoring before performing polysomnography (PSG). Subsequently all the subjects underwent PSG test. Forty subjects were diagnosed as having OSAHS, and twenty subjects had no OSAHS. These 20 non-OSAHS subjects served as controls. Compared with the PSG results the clinical usefulness of the measurement of orexin-A concentration in serum was assessed as a diagnostic predictor to screen patients with OSAHS. Correlation between orexin-A levels and apnea hypoventilation index (AHI), micro-arousal index (MAI) and lowest SaO2 (LSaO2) were analyzed.

RESULTSThe serum orexin-A levels in the OSAHS group [(0.49 +/- 0.10) microg/L] was significantly higher than that of the control group [(0.28 +/- 0.11) microg/L, P < 0.01]. If a patient's level of orexin-A was higher than 0.36 microg/L, the patient more likely to have OSAHS. The sensitivity rate was 85.0% and the specificity was 80.0%. Serum orexin-A levels in children with OSAHS correlated positively with the AHI (r = 0.427, P < 0.05) and MAI (r = 0.468, P < 0.05), but correlated negatively with the LSaO2 (r = -0.527, P < 0.01) and the mean oxygen saturation (MSaO2) (r = -0.541, P < 0.01), not correlated significantly with the BMI (r = -0.212, P > 0.05). The serum orexin-A levels in the OSAHS children after who under went tonsillectomy and adenoidectomy significantly decreased (P < 0.05) 3 months after surgery as compared with pre-operation level.

CONCLUSIONThese findings suggest that the serum level of orexin-A could be used as a predictor in screening for OSAHS children and a biological marker of the severity of OSAHS children.