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

Abstract

Recent evidence suggests that vitamin D deficiency is associated with CVD, impaired kidney function and proteinuria. To date, no study has evaluated these associations in renal transplant recipients (RTR) adjusting for body adiposity assessed by a 'gold standard' method. This study aimed to evaluate the vitamin D status and its association with body adiposity, CVD risk factors, estimated glomerular filtration rate (eGFR) and proteinuria in RTR, living in Rio de Janeiro, Brazil (a low-latitude city (22°54'10"S)), taking into account body adiposity evaluated by dual-energy X-ray absorptiometry (DXA). This cross-sectional study included 195 RTR (114 men) aged 47·6 (sd 11·2) years. Nutritional evaluation included anthropometry and DXA. Risk factors for CVD were hypertension, diabetes mellitus, dyslipidaemia and the metabolic syndrome. eGFR was evaluated using the Chronic Kidney Disease Epidemiology Collaboration equation. Serum 25-hydroxyvitamin D (25(OH)D) concentration was used to define vitamin D status as follows: 10 % (n 19) had vitamin D deficiency (30 ng/ml). Percentage of body fat (DXA) was significantly associated with vitamin D deficiency independently of age, sex and eGFR. Lower 25(OH)D was associated with higher odds of the metabolic syndrome and dyslipidaemia after adjustment for age, sex and eGFR, but not after additional adjustment for body fat. Hypertension and diabetes were not related to 25(OH)D. Lower serum 25(OH)D was associated with increasing proteinuria and decreasing eGFR even after adjustments for age, sex and percentage of body fat. This study suggests that in RTR of a low-latitude city hypovitaminosis D is common, and is associated with excessive body fat, decreased eGFR and increased proteinuria.

The Role of Vitamin D in Kidney Transplantation Outcomes: A Systematic Review

“…Out of these 196 articles 40 were eligible for full-text analysis. Ultimately, sixteen articles were included in this review [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ] ( Figure 1 ). The rest of the articles were excluded as the design, protocol and/or methodology used investigated a different PICO question to those of our study.…”

Vitamin D Metabolites, Body Composition, and Nutritional Status in Patients in the Long Term After Kidney Transplantation

“…Similar to our observations, the authors show that fat tissue amount and BMI are independent factors affecting 25(OH)D level, but this was not observed for eGFR or proteinuria [ 28 ]. Excess fat tissue, particularly indexes of obesity, were found to be strongly associated with vitamin D insufficiency among Brazilians after KTx [ 29 ]. They showed that patients with either vitamin D deficiency or insufficiency had significantly higher values of body fat and greater weight gain since transplantation [ 29 ].…”

“…Excess fat tissue, particularly indexes of obesity, were found to be strongly associated with vitamin D insufficiency among Brazilians after KTx [ 29 ]. They showed that patients with either vitamin D deficiency or insufficiency had significantly higher values of body fat and greater weight gain since transplantation [ 29 ].…”

“…We noticed a reverse relationship between calcitriol and HDL level. Data assessing associations between particular components of lipids and vitamin D metabolites are unequivocal – some of them show the relationship, some do not [ 29 , 38 , 39 ]. However, we must emphasize that most of our patients (73%) had received statin therapy, so the described improvement cannot be assigned only to the beneficial influence of vitamin D. Sikgenc et al showed that vitamin D supplementation in KTx patients decreases TC and TG levels [ 38 ].…”

Vitamin D Deficiency in Renal Disease

“…Marchal et al established a significant association between lower 25VD and vascular calcification after KT [85]. However, a more recent study did not find a relationship between VD status and post-transplant hypertension and major CV events [97]. One of the aims of the already mentioned trial VITALE is to assess the effect of cholecalciferol supplementation on blood pressure control and CVD rates in KTRs [96].…”