Persistent secondary hyperparathyroidism after renal transplantation in children

Abstract

Secondary hyperparathyroidism (HPTH) is a frequent complication of chronic kidney disease (CKD). Renal transplantation corrects the biochemical abnormalities that cause HPTH; however, HPTH persists in some patients. The factors that contribute to the persistence of HPTH after transplantation in children are poorly understood. We examined 57 children who underwent renal transplantation and determined whether baseline clinical and biochemical parameters could predict the persistence of HPTH at 1 year post-transplantation, using multivariate logistic regression. At the time of transplantation, serum parathyroid hormone (PTH) levels were >300 pg/ml in 60%, 150-300 pg/ml in 17%, and <150 pg/ml in 23% of recipients. HPTH (PTH >73 pg/ml) persisted in 78% of patients at 6 months and in 56% at 1 year after transplant. Older age at transplantation was the strongest predictor of HPTH at 1 year (OR=1.17, P<0.05). After adjustment for age, other baseline clinical or laboratory parameters were not predictive of HPTH at 1 year. The relationship between older age and persistent HPTH may be explained by longer duration of CKD. Given the potential morbidities associated with persistent HPTH, the role of interventions that would prevent or reverse persistent HPTH post-transplantation requires further investigation.

Parathyroid hormone levels in long-term renal transplant children and adolescents

“…Recently, a primary role of FGF23 as the cause of hypophosphatemia after transplantation has also been advocated in those recipients with persistent renal phosphate wasting [26]. The prevalence of hypercalcemia was lower than previously reported [3,8], occurring in only 6.2% of patients at 6 months and in 4.1% at 1 year post-transplant, but we did not measure ionized calcium, which could have underestimated the result. Moreover, difference in population analyzed and growing attention to Ca-P product before the transplant in the last years could explain our results compared to previous data.…”

“…Multivariate analysis indicated pre transplant iPTH, dialysis duration, creatinine clearance and hypophosphatemia as predictors of persistent hyperparathyroidism (Table 4). In two previous pediatric studies, risk factors for the persistence of high levels of iPTH after transplant were: high PTH at the time of transplant and duration of dialysis in one study [4], and age at transplantation in the second one [3]. In our study, two further risk factors emerged: reduced creatinine clearance and hypophosphatemia.…”

“…MatsudaAbedini examined the natural history of hyperparathyroidism in 57 transplanted children followed for the first year after transplantation and found that PTH above normal values (> 73 pg/ml) persisted in 78% of patients at 6 months and in 56% at 1 year post-transplant [3]. Similarly, in a study on 41 children, Koch Nogueira reported serum PTH above normal range (>55 pg/ml) 90 days after renal transplant in 17% of children with a pre-emptive transplant, and in 54% of children with a variable period of dialysis before transplant [4].…”

“…Post-transplant hyperparathyroidism is associated with hypercalcemia and hypophosphatemia in 20-30% of the transplanted patients [3]. Hypercalcemia is related to persistent high levels of PTH and calcitriol which, in turn, can lead to increased intestinal absorption, renal tubular reabsorption and mobilization of calcium from bone.…”

“…Recovery of a good renal function corrects phosphorus retention and calcitriol production. Nevertheless, secondary hyperparathyroidism persistence in children has been variably reported as about 50% and varies according to the definition of "normal" PTH level after transplant and to the time of assessment [3][4][5]. Duration of chronic kidney disease and high serum PTH before transplant emerged as significant determinants of persistent secondary hyperparathyroidism after transplant in children [3,4].…”