Associação dos níveis séricos e urinários de magnésio com a progressão da doença renal e aterosclerótica em portadores de doença renal crônica não-dialítica

Abstract

The reduction in the glomerular filtration rate (GFR) causes decreasing and unbalancing in some divalent elements, such as magnesium (Mg2+). Several evidence suggest that low serum Mg2+ levels may be a risk factor for kidney disease and cardiovascular events, but there is still a gap about the role of urinary Mg2+ in these outcomes. Thus, the present study investigated the effects of serum and urinary Mg2+ levels in non-dialytic CKD patients, in relation to the progression of kidney and atherosclerotic disease. A cohort study was developed with a sample of 124 individuals with GFR 15-59mL/min/1.73m² monitored at the Prevention Center of Kidney Diseases at the University Hospital of the Federal University of Maranhão. The patients were evaluated at 3 steps: t1 (inclusion), t2 (12 months) and t3 (24 months), about clinical, laboratory and imaging aspects. The patients showed mean age of 59.6 (12.1) years and 66 (53.2%) were female. Regarding the etiology of CKD, the main cause was hypertension (n=51; 41.1%), followed by diabetes (n=28; 22.6%). Most cases were patients with CKD stage 3A (n=53; 42.7%). Seventy (56.5%) patients had albuminuria levels <30mg/24h. Mineral-bone disorder markers (calcium, phosphorus and alkaline phosphatase) were normal, but there was a high prevalence of patients with increased PTH (n=51; 41.1%). Glycemic control was compromised in about half of the cases. Regarding dyslipidemia, there was a higher prevalence of low HDLc (n=57; 46.0%) and isolated hypertriglyceridemia (n=44; 35.5%). Seventy four (59.7%) patients were identified with a coronary calcification score (CCS) >0, 56 (45.2%) with carotid intima-media thickening (CIMT) and 70 (56.5%) with carotid walls showing calcifications. In the multivariate analysis, it was observed that the lowest tertile of serum Mg2+ was associated with progression of albuminuria (β=78,473, p=0.028), while the highest tertiles of urinary Mg2+ (24h) were associated with GFR (β=5.264, p=0.011), albuminuria (β=104.185, p=0.005), coronary calcification (β=354.147, p=0.005) and carotid thickness (β=0.063, p=0.046). Compared to serum levels, urinary Mg2+ showed a greater number of associations with indicators of progression of renal and atherosclerotic disease in the evaluated sample, and can be used in clinical practice for monitoring of patients with high cardiovascular risk.