Status of vitamin D and parameters of calcium homeostasis in renal transplant recipients in Nepal: a cross sectional study

Abstract

BackgroundVitamin D, apart from being an important part of the “calcium-vitamin D-parathyroid hormone” endocrine axis, has diverse range of “non-calcemic” biological actions. A high prevalence of vitamin D deficiency has been observed in renal transplant recipients (RTRs) worldwide. This study aimed to determine the prevalence of hypovitaminosis D in Nepalese RTRs and interrelations between serum 25-hydroxyvitamin D [25(OH) D] and other biochemical parameters.MethodsA total of 80 adult RTRs visiting a university hospital were enrolled in this cross sectional study. Serum 25(OH) D and intact parathyroid hormone (iPTH) were measured using Enhanced Chemiluminiscent Immunoassay. The RTR population was categorized into recent transplant recipients (≤1 year) and long term recipients (> 1 year). The vitamin D status was defined as per NKF/KDOQI guidelines. SPSS version 20.0 was used to analyze the data. Appropriate statistical tests were applied to compare variables between groups and establish correlation. P < 0.05 was considered to be statistically significant.ResultsThe mean age of the recipients was 38.11 ± 11.47 years (68 males, 85.0%). Chronic glomerulonephritis was the leading cause of CKD. The two RTR groups (recent and long term) didn’t differ in demographic and biochemical characteristics. 83.75% of the recipients had PTH levels above the upper limit of the recommended range for their stage of CKD. 57.5% had hypocalcemia and none of the recipients had hypercalcemia. The median serum 25(OH) D was 24.15 ng/ml (8.00–51.50 ng/ml). Only 27.5% had sufficient vitamin D status whereas 53.8% were vitamin D insufficient and 18.8% were vitamin D deficient, the distribution almost comparable in the 2 transplant group. The serum 25(OH) D was not significantly affected by the time post-transplant, gender and sunlight avoidance. There was a significant negative correlation between serum 25(OH) D and iPTH (Pearson’s r = − 0.35, P = 0.001), but not so with the graft function.ConclusionThere is a high prevalence of vitamin D insufficiency in RTRs. The deficiency status is not corrected despite of nutritional improvement and normalization of GFR post-transplantation and likely exacerbates secondary hyperparathyroidism. Vitamin D supplementation coupled with sensible sun exposure could be important strategies in optimization of the vitamin D status in this population.

Vitamin D status in an Australian patient population: a large retrospective case series focusing on factors associated with variations in serum 25(OH)D

“…The majority of patients from nephrology at RMH were treated for chronic kidney disease (CKD). Vitamin D levels are generally low in these patients, as CKD is associated with low levels of vitamin D, especially in patients with end-stage renal disease and kidney transplant recipient 55–59. Our findings are consistent with results from previous studies that demonstrated the association between low vitamin D levels and CKD.…”

Age, Gender and Season Are Good Predictors of Vitamin D Status Independent of Body Mass Index in Office Workers in a Subtropical Region

“…In the elderly, a significant negative correlation between serum 25(OH)D and corrected serum calcium was found [ 45 ]. Conversely, there was no significant correlation between serum 25(OH)D and corrected total serum calciumin some reports [ 46 , 47 ]. Besides hypovitaminosis D, causes of hypocalcemia include hypoparathyroidism [ 48 ], intestinal malabsorption, magnesium depletion [ 49 ] and hyperphosphatemia [ 30 ].…”

Prevalence and risk factors of post-kidney transplant hyperparathyroidism: a single-center study

“…В то же время известно, что сывороточный магний не является надежным маркером его содержания в организме и при нормальном его уровне в крови возможна магниевая недостаточность [27]. Не установлено также взаимосвязи между плазменными концентрациями ПТГ и витамина D в отличие от исследования Timalsina S. et al [18]. Более того, витамин D у всех реципиентов и с нормальной и с гиперфункцией ОЩЖ был ниже принятого в общей популяции целевого диапазона [29].…”

“…Факторами риска развития ГПТ в посттрансплантационном периоде явились длительность диализной терапии более 18…”

“…Одни авторы сообщили о 40-50% реципиентов с уровнем ПТГ в крови в первый послеоперационный год более 130 пг/мл, другие -только о 18%; через несколько лет после трансплантации почки от 17% до трети реципиентов имели ГПТ [8,[13][14][15]. Анализируются разнообразные факторы риска развития посттрансплантационного ГПТ -в отношении одних получены убедительные данные, в отношении других исследования продолжаются [13,[15][16][17][18]. Обращает внимание немногочисленность информации о ГПТ после трансплантации почки, которая представлена исключительно в зарубежных публикациях.…”