Evaluation of iron metabolism in obstructive sleep apne syndrom

Aim: Obstructive sleep apnea is characterized by repeated disruptions of breathing during sleep. In this study, we aimed to investigate markers that affect systemic iron balance in obstructive sleep apnea. Material and methods: This study including 37 patients with obstructive sleep apnea, evaluated by polysomnography and 36 healthy volunteer. The patients were divided into three groups according to their apnea-hypopnea index ( mild 5-15, moderate 15-30, severe > 30). Fasted blood samples were collected and samples were analyzed for iron, total iron binding capacity, ferritin, IL-6, hsCRP, soluble transferrin receptor, hepcidin, hemojuvelin. Iron and total iron binding capacity were measured using an colorimetric method. Ferritin, IL-6, hsCRP, soluble transferrin receptor, hepcidin and hemojuvelin were measured by ELISA. Results were assesed by Statistical Package for Social Sciences (SPSS, version 18), using statistical tests including Mann-Whitney U test and Pearson's or Spearman's correlation coefficient. P value < 0.05 was considered as a significant level. Results: IL-6, hsCRP, ferritin, soluble transferrin receptor and hemojuvelin showed a statistically significant increase in obstructive sleep apnea. Iron and total iron binding capacity, hepcidin values did not differ. There was no a statistically significant correlation between apnea-hypopnea index and parameters (iron, total iron binding capacity, ferritin, IL-6, hsCRP, soluble transferrin receptor, hepcidin and hemojuvelin) (p> 0.05). We demonstrated a statistically significant correlation, IL-6 between hsCRP (r=0.322, p=0.005), hsCRP between soluble transferrin receptor (r=0.318, p=0.006) and ferritin between hemojuvelin (r=0.925, p<0.0001) Conclusion: In our study, we found higher IL-6, hsCRP, ferritin, soluble transferrin receptor and hemojuvelin in obstructive sleep apnea. However, hepcidin, iron and total iron binding capacity are not elevated in obstructive sleep apnea. Further studies with detailed must be planned to explain the exact mechanism of iron in obstructive sleep apnea. Keywords: Obstructive sleep apnea syndrome, IL-6, Hepcidin, Hemojuvelin