Status de vitamina D e fatores associados em indivíduos submetidos a transplante renal: um estudo longitudinal

Abstract

Hypovitaminosis D has been a frequent finding in renal patients. In kidney transplant recipients, this may cause progression of albuminuria, increasing the decline in renal function and the risk of graft loss. The objective of this study was to evaluate the vitamin D status in kidney transplant recipients and its relation with renal function parameters at time zero, 3 months and 6 months post-transplantation. This is a longitudinal study with 46 kidney transplant recipients from August 2015 to January 2017. At zero time, 3 subjects were excluded due to vitamin D supplementation (n = 46), in 3 months there was 1 death, 1 (n = 43) and at 6 months 1 patient presented acute rejection of the graft (n = 42). The subjects were evaluated using anthropometric evaluation, a sun exposure questionnaire, biochemical evaluation, including 25-hydroxyvitamin D [25(OH)D], and urine collection to evaluate the albumin: creatinine ratio (ACR) at all times studied. The glomerular filtration rate (GFR) was computed by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. The median age of the subjects was 44 years, predominantly males (60.9%; n=28), and with brown ethnicity (73.9%; n=34). Most of the subjects had hypovitaminosis D during the three studied periods. In subjects with adequate Vitamin D status at 6 months post-transplant, the sun exposure was significantly lower. At 6 months post-transplant, 45.2% (n=19) presented with hypovitaminosis D at all times, and 19.1% (n=8) developed hypovitaminosis D at 3 months, totalizing 27 individuals with this profile. Of these, 37.0% (n=37) had no improvement in the GFR. The ACR of subjects with hypovitaminosis D were higher at six months post-transplant (p=0.037). This was negatively correlated with the 25(OH)D (r=- 0.358; p=0.02). The parathyroid hormone (PTH) had a negative influence on GFR at time zero but was positively correlated with ACR at six months post-transplantation (r=0.420; p=0.007). Therefore, there is a high frequency of hypovitaminosis D up to 6 months after renal transplantation, which may be related to greater changes in graft renal function. More studies are needed to support interventions, such as supplementation, in order to obtain better results after renal transplantation.