Overweight and body fat are predictors of hypovitaminosis D in renal transplant patients

Abstract

BackgroundHypovitaminosis D has been frequently reported after renal transplantation, but the impact of obesity and other factors in the reduction of vitamin D levels is not well established. We aimed to evaluate risk factors contributing to hypovitaminosis D among nondiabetic renal transplant recipients (RTR) with serum creatinine <2.0 mg/dL, at least 6 months after transplantation.MethodsOne hundred RTR were subjected to anthropometric evaluation and body composition assessment through bioelectrical impedance analysis; blood samples were drawn for biochemical and hormonal determinations and clinical data were retrieved from the medical records.ResultsHypovitaminosis D was observed in 65% and overweight (body mass index, BMI >25 kg/m2) in 59% of cases with a significant median weight gain after transplantation of 5.1 kg. An inadequate distribution of body fat was evidenced in 50% of males and in 58% of females. Patients with either vitamin D deficiency or insufficiency presented significantly higher median values of body fat and weight gain since transplantation, as well as lower lean mass compared with patients with normal vitamin D levels (P < 0.001). Moreover, median values of waist circumference, BMI, serum leptin and parathyroid hormone levels were significantly higher in the group with vitamin D deficiency. A multivariate linear regression analysis then revealed that body fat and leptin levels, but not skin color, gender, age, glucocorticoid use, renal function, microalbuminuria and other confounding factors, were independently associated with low levels of 25 hydroxyvitamin D3 even after adjustments for seasonal variations.ConclusionIn conclusion, the present study showed body fat and serum leptin levels to be the only independent risk factors for hypovitaminosis D among RTR.

Vitamin D status in renal transplant recipients living in a low-latitude city: association with body fat, cardiovascular risk factors, estimated glomerular filtration rate and proteinuria

“…Weight gain during the 1st year post-tx was significantly higher in the vitamin D-deficient group in the present study. Similar findings were observed by Baxmann et al (36) in RTR. Several mechanisms have been proposed to explain the lower levels of 25(OH)D in obese individuals, and the main mechanism appears to be the sequestration of vitamin D by adipose tissue (51) .…”

“…Some studies conducted in Brazil also found that more than half of the participants presented hypovitaminosis D. These studies included the general population (32,33) and chronic kidney disease (CKD) patients in predialysis (34,35) . In Brazil, to date, only one study evaluated the prevalence of hypovitaminosis D in RTR (36) , and was conducted in the city of São Paulo, which has a higher latitude (23°32'51"S) than Rio de Janeiro, and the prevalence of hypovitaminosis D was higher (65 %). As expected, the prevalence of vitamin D deficiency/insufficiency in the present study was lower than that observed in previous studies conducted with RTR in other countries with higher latitudes (12)(13)(14)(37)(38)(39) .…”

Association of Vitamin D Levels With Kidney Volume in Autosomal Dominant Polycystic Kidney Disease (ADPKD)

“…Hypovitaminosis D was more prevalent for patients who had their blood samples drawn during winter, as already evidenced in our country (29, 30). Some studies have reported an association between hypovitaminosis D with BMI (29, 31) possibly due to either the low exposure of obese individuals to sunlight or sequestration and storage of vitamin D in adipose tissue (32). We did not observe a higher BMI, waist circumference or percentage of body fat in vitD-insufficient patients, differing from previous studies by our group and others in CKD or after renal transplant (29, 31), but corroborating with Gronborg et al (33), who found no association.…”

Low socio‐economic status is a newly identified independent risk factor for poor vitamin D status in severely obese adults

“…Finally, it has been suggested that vitamin D deficiency was associated with an increased risk of developing obesity in subjects who were non-obese (13) . Inversely, obesity appeared to be a risk factor for hypovitaminosis D in nondialysed patients with chronic kidney disease and in renal transplant patients (14,15) . Taken together, these studies have highlighted a strong link between MetS, obesity and hypovitaminosis D.…”