Body adiposity predictors of vitamin D status in nondialyzed patients with chronic kidney disease: A cross-sectional analysis in a tropical climate city.
OBJECTIVE
The association of vitamin D status with high body adiposity is poorly investigated in the chronic kidney disease (CKD) population. The aim of the present study was to describe vitamin D status and to identify body adiposity predictors of vitamin D deficiency, in a nondialyzed CKD population inhabiting a tropical city.


METHODS
This cross-sectional study included patients with CKD, defined as estimated glomerular filtration rate (eGFR) <60 mL/min, regularly treated by an interdisciplinary team in an outpatient university clinic, set in a Brazilian city (latitude: 22°54'S; 43°12'W). Adiposity parameters analyzed were body mass index (BMI), total body adiposity (dual-energy x-ray absorptiometry [DXA] and body adiposity index [BAI]), and central body adiposity (DXA-trunk fat and waist-to-height ratio [WHtR]). Laboratory parameters included serum concentrations of 25-hydroxyvitamin D, phosphate, parathyroid hormone, and insulin (insulin resistance [IR evaluation: homeostasis model assessment; HOMA]).


RESULTS
We studied 244 patients (54.9% men; n = 134) with median eGFR = 29.1 mL/min and BMI 26.1 kg/m2, comprising 58.2% (n = 142) with overweight/obesity. The vitamin D status was sufficient (≥30 ng/dL) in 43%, insufficient (20-30 ng/dL) in 37%, and deficient (<20 ng/dL) in 20%. Total body adiposity was the independent predictor of vitamin D deficiency (DXA: odds ratio [OR], 2.3; 95% confidence interval [CI], 1.1-5; P = 0.03; BAI: OR, 1.9; 95% CI, 1-3.8; P = 0.02), whereas BMI, DXA-trunk fat, and WHtR showed no correlation. Higher serum phosphorus and hyperparathyroidism were related (P < 0.05) to vitamin D deficiency. IR was not independently associated with 25-hydroxyvitamin D concentration.


CONCLUSIONS
Just under half of the CKD population presented sufficient concentration of 25-hydroxyvitamin D. Total body adiposity, independent of age and eGFR, regardless if evaluated by DXA or BAI, was the predictor of vitamin D deficiency, which in turn was associated with higher serum phosphorus and hyperparathyroidism, but not with IR.
Department of Applied Nutrition, Nutrition Institute, Rio de Janeiro State University, Rio de Janeiro, Brazil. Electronic address: Mibsab@terra.com.br.
Maria Inês
MI
Barreto Silva
Postgraduation Program in Medical Science, Rio de Janeiro State University, Rio de Janeiro, Brazil.
Vanessa Vicente de Souza
VV
Cavalieri
Nephrology Division, Rio de Janeiro State University, Rio de Janeiro, Brazil.
Carla Cavalheiro da Silva
CC
Lemos
Department of Applied Nutrition, Nutrition Institute, Rio de Janeiro State University, Rio de Janeiro, Brazil.
Márcia Regina Simas Torres
MR
Klein
Nephrology Division, Rio de Janeiro State University, Rio de Janeiro, Brazil.
Rachel
R
Bregman
D015652:25-Hydroxyvitamin D 2 / Q000097:blood; D050154:Adiposity / Q000208:ethnology; D000368:Aged; D015992:Body Mass Index; D001938:Brazil / Q000453:epidemiology; D002112:Calcifediol / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009752:Nutritional Status / Q000208:ethnology; D009765:Obesity / Q000097:blood / Q000150:complications / Q000208:ethnology / Q000503:physiopathology*; D050177:Overweight / Q000097:blood / Q000150:complications / Q000208:ethnology / Q000503:physiopathology*; D015995:Prevalence; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000150:complications / Q000208:ethnology / Q000503:physiopathology*; D012307:Risk Factors; D012720:Severity of Illness Index; D014329:Tropical Climate; D014808:Vitamin D Deficiency / Q000453:epidemiology / Q000208:ethnology / Q000209:etiology* / Q000503:physiopathology; D065927:Waist-Height Ratio
D015652:25-Hydroxyvitamin D 2; D002112:Calcifediol
25-hydroxyvitamin D; Adiposity; Chronic kidney disease; Overweight/obesity