Associação dos níveis séricos e urinários de magnésio com a composição corporal e marcadores inflamatórios em portadores de doença renal crônica não dialítica

Abstract

Reduced magnesium (Mg) levels may be associated with mortality or adverse cardiovascular outcome in chronic kidney disease (CKD). The aim of this study was to evaluate the association of serum and urinary Mg levels with body composition and inflammatory markers in patients with non-dialysis dependent CKD. Longitudinal, prospective study for a period of 24 months, with a sample of patients with CKD on non-dialysis treatment, in stages 3A, 3B and 4, of both sexes and aged 20 years or older. Data collection occurred in three steps: t1 (inclusion), t2 (12 months) and t3 (24 months). At each moment of the study, sociodemographic, lifestyle, anthropometric, body composition, clinical and laboratory data were collected. Sociodemographic, lifestyle, anthropometric, body composition, clinical, and laboratory data were collected. Venous samples were collected after a 12-hour night fast and included: creatinine, Mg, calcium, sodium, uric acid, phosphorus, parathormone, vitamin D, triglycerides, cholesterol, high density lipoprotein, low density lipoprotein, fasting glycemia, alkaline phosphatase, complete blood count, interleukin 6 (IL6) and ultrasensitive C-reactive protein. The 24-hour urine was used to dose urinary excretion of Mg and creatinine. The dietary intake of magnesium was estimated by means of the 24-hour food recall. The anthropometric evaluation was performed by measuring body mass, height, abdominal sagittal diameter and waist circumference (WC), calf circumference and neck circumference. To evaluate body composition, Dual-energy X-ray absorptiometry and Air Displacement Plethysmography were used. A linear regression model with random effects was ajusted to investigate the impact of serum and urinary Mg levels on body composition and inflammatory status. The final study sample consisted of 134 patients with a mean age of 60.2±12.0 years and 52.2% were female. The prevalence of excess weight according to the body mass index was 57.1% and the percentage of body fat (%BF) was high at 66.9%. Women had a higher prevalence of high %BF (77.5% vs 56.6%; p=0.005). Men had a higher average consumption of calories (p<0.001). As for the intake of macro and micronutrients, no statistically significant difference was observed between genders. There was no statistically significant difference between serum and urinary Mg levels with CKD stages. In the adjusted model, percentage of lean mass and dietary intake of magnesium were positively associated with serum magnesium. Triglyceride levels, uric acid, WC and fat mass percentage were negatively associated with serum magnesium. For urinary Mg, in the adjusted model, estimated glomerular filtration rate, IL6, dietary Mg intake and lean mass percentage showed a positive association. The results of this study demonstrated that serum and urinary levels of Mg were positively associated with lean body mass. Total and core body fat were negatively associated with serum magnesium. Furthermore, a positive correlation was shown between urinary magnesium and the inflammatory state. A low dietary intake of Mg was identified in the surveyed population