One year vitamin D and parathyroid hormone influence in patients with OSAS and CPAP treatment

Obstructive sleep apnea syndrome (OSAS) is characterized by intermittent hypoxemia and disturbance of circadian rhythms. Continuous positive airway pressure (CPAP) treatment affects hormone and bone metabolism. Aim: Monitoring of the levels of 25 (OH) vitamin D (Vit.D) and parathyroid hormone (PTH) in patients with newly diagnosed OSAS after initiating CPAP treatment for 12 months period. Material and methods: 30 patients with newly diagnosed OSAS and 20 healthy controls without Vit.D substitution were studied. The patients were followed up on the 6th and 12th months after initiation of CPAP treatment. Results: The patients with newly diagnosed OSAS were with statistically higher PTH value (5.93 ±1.82 pmol/l, p <0.001). A severe Vit.D deficiency was observed in both groups (18.91± 8.37nmol/ l in OSAS vs.19.80 ± 13.69 nmol/l in controls, p = 0.08). There was a statistically significant difference in Vit.D levels below and above 25 nmol/ l and mean desaturation time during sleep (12.50± 5.41% vs. 7.60±3.72%, p=0.036). A statistically significant negative correlation between level of Vit.D and desaturation time during sleep was found (r = -0.398, p=0.036). A statistically significant increase of Vit.D level (43.29 ± 31.64nmol/l) compared to baseline (18.91 ± 8.37nmol/l) was observed at 6th month of CPAP treatment (p=0.001). On the 12th month there was a statistically significant decrease in PTH levels (4.49±1.70 pmol/l, p=0.028). Conclusions: Vitamin D deficiency and secondary osteoporosis are found in OSAS. The severe vitamin D deficiency correlates with the duration of desaturation during sleep and the severity of OSAS. Long-term treatment with CPAP increases Vit.D levels.