Serum levels of magnesium and their relationship with CRP in patients with OSA

Low levels of magnesium (Mg) are associated with chronic inflammatory stress. Some animal studies have reported that a moderate deficiency of Mg, similar to that which occurs in humans, may increase inflammatory or oxidative stress stimulated by other factors, such as disrupted sleep or sleep deficiency. This cross-sectional study evaluated the relationship between serum levels of Mg and the inflammatory response in patients with a new diagnosis of obstructive sleep apnea (OSA). This clinical, retrospective study registered 68 patients with newly diagnosed mild to severe OSA and 30 without OSA. The Apnea-Hypopnea Index (AHI), oxygen desaturation index (ODI), time until blood hemoglobin oxygen saturation < 90 % (SpO(2) < 90 %), and mean blood hemoglobin SpO(2) were measured. Serum levels of Mg, plasma C-reactive protein (CRP), and total sleep time (TST) by polysomnography were also measured. Mg levels were lower in patients with OSA than those in controls matched for age, sex, and body mass index (BMI). Patients with OSA had substantially higher plasma CRP concentrations than controls. A negative correlation was observed between the AHI and ODI and Mg levels. Significant differences in Mg and CRP levels were observed between patients with AHI scores of 5-15 and scores >= 30 based on OSA severity but independent of BMI. Furthermore, the AHI, ODI, TST < 90 %, and mean SpO(2) significantly correlated with CRP. A significant negative correlation was observed between Mg and CRP levels (p < 0.0001). Our results show that Mg levels changed depending on the presence and severity of OSA. Low levels were associated with a higher CRP concentration in patients with OSA.