Abstract 552: Vitamin D in Chronic Kidney Disease is Aassociated with Total or Central Body Adiposity?

Abstract

Introduction: Obesity is reported as an important contributor for vitamin D (VitD) deficiency. Nevertheless, most of the studies use body mass index (BMI) to evaluate this relationship and results are not clear. In CKD, obesity and VitD deficiency are common conditions, however the association of body adiposity and VitD in nondialyzed CKD patients is not known. Objective: Determine the association of VitD with total and central body adiposity in nondialyzed CKD patients. Methods: Cross-sectional study conducted in nondialyzed CKD outpatients under regular treatment. Inclusion criteria: clinically stable; age≥18 years; estimated glomerular filtration rate (CKD-EPI) (eGFR)≤ 60 ml/min. Body adiposity: BMI (classified by WHO criteria; 1998); waist circumference (WC); waist-to-height ratio (WheiR); waist-to-hip ratio (WHR); total body adiposity (TBA) by dual-energy X-ray absorptiometry (DXA) and by body adiposity index (BAI). VitD[25(OH)D] analysed by Passing-Bablok method and leptin, used as TBA marker, by radioimmunoassay. Participants were stratified as: VitD-deficient (<20 ng/ml; 23%/n=40; VitD=16±3 ng/ml) and VitD-no-deficient (≥20 ng/ml; 77%/n=135; VitD=31±8 ng/ml). Results: We studied 175 nondialyzed CKD (57.7% men/n=101), 66±13 years, eGFR=29±13ml/min., BMI=26±5 kg/m2, VitD=27±9.7 ng/ml. CKD stages (CKD-s) profile was (%/n): 3A-15%/26; 3B-32%/56; 4-39%/68; 5-14%/25. VitD-deficient patients compared with VitD-no-deficient showed higher TBA evaluated by DXA (38±7 vs. 33±9%,p=0.003), BAI (32±7 vs. 29±5%,p=0.009) and leptin (median; interquartil interval=6.2; 5-10 vs. 11; 10-19 ng/dl,p=0,01), but showed no differences (p≥0.05) for BMI and central adiposity parameters (WC;WheiR;WHR). Serum 25(OH)D values were negatively associated with TBA (DXA: r= -0.3; p=0.0008; BAI: r= -0.22; p=0.008), but was not associated with BMI and with WC, WheiR, WHR. In multiple regression analysis TBA (by DXA and by BAI), but not BMI, was independently associated with VitD (p=0.001) after adjusted by age, gender, eGFR. Conclusion: Total body adiposity, but not BMI or central adiposity, was independently associated with vitamin D levels in this population with CKD.