Correlation of serum magnesium with cardiovascular risk factors in maintenance hemodialysis patients--a cross-sectional study.

BACKGROUND AND OBJECTIVES: Changes in serum magnesium (Mg) may affect some clinical features of patients on maintenance hemodialysis (HD). The aims of our study were to evaluate the correlation between serum Mg concentration and clinical characteristics in Chinese HD patients, and to determine whether it has any relevance for cardiovascular outcomes. MEASUREMENTS: 98 chronic HD patients were recruited, and clinical features related to cardiovascular disease (CVD) were measured: the correlation between Mg and these characteristics was analyzed.
RESULTS: In patients who were hypomagnesemic, serum Mg, creatinine (Scr), albumin (Alb), pre-albumin (pre-Alb) levels, protein catabolic rate per normalized body weight (nPCR), dietary protein intake (DPI), triceps skin fold (TSF) thickness, mid-arm circumference (MAC), mean mid-arm circumference (MAMC), subjective global assessment (SGA) scores and Kt/V were lower than in hypermagnesemic patients. On the other hand, the incidence of intradialytic hypotension (IDH), levels of serum calcium (Ca), phosphorus (P), intact parathyroid hormone (iPTH), C reactive protein (CRP), high-density lipoprotein cholesterol (HDL-c) levels, carotid artery plaque (CAP), and carotid intima-media thickness (CIMT) (all p<0.05, respectively) were higher in patients with low serum magnesium. Correlation analysis showed Mg to be not only positively associated with the nutritional status index, but also negatively correlated with other characteristics, such as IDH incidence, Kt/V, Ca, P, iPTH, CRP, HDL-c, CAP, CIMT (p<0.05, respectively). There was no significant correlation between Mg and low-density lipoprotein cholesterol (LDL-c), lipoprotein-a (LP-a), cholesterol (TC), serum triglycerides (TG), or subjective global assessment (SGA) scores (p>0.05, respectively). Multiple linear regression analysis showed that Mg was negatively associated with CIMT, a direct predictor of CVD (β coefficient=-0.260, p=0.009).
CONCLUSIONS: It is suggested that lower serum Mg reflects poorer nutritional status and that it is also associated with other risk factors for cardiovascular disease in hemodialysis patients, such as greater incidence of IDH, poorer HD adequacy, deteriorating calcium-phosphate metabolism, inflammation and CIMT.