Mineral and bone disorder after kidney transplantation: a single-center cohort study

BACKGROUND: The assessment and prevention of mineral and bone disorder (MBD) in kidney transplant recipients (KTRs) have not been standardized. This study aimed to evaluate MBD one year after kidney transplantation (KT) and identify the influencing factors of MBD. METHODS: A total of 95 KTRs in our center were enrolled. The changes in bone mineral density (BMD) and bone metabolism biochemical markers, including serum calcium (Ca), phosphorus(P), 25-hydroxyvitamin D(25(OH)vitD), intact parathyroid hormone (iPTH), bone alkaline phosphatase, osteocalcin (OC), type I collagen N-terminal peptide and type I collagen C-terminal peptide (CTx), over one year after KT were assessed. The possible influencing factors of BMD were analyzed. The relationships between bone metabolism biochemical markers were evaluated. The indicators between groups with or without iPTH normalization were also compared. RESULTS: MBD after KT was manifested as an increased prevalence of hypophosphatemia and bone loss, persistent 25(OH)vitD deficiency, and partially decreased PTH and bone turnover markers (BTMs). Femoral neck BMD was positively correlated with body mass index (BMI) and postoperative 25(OH)vitD, and negatively correlated with postoperative PTH. Lumbar spine BMD was positively correlated with BMI and preoperative TG, and negatively correlated with preoperative OC and CTx. BMD loss was positively associated with glucocorticoid accumulation. Preoperative and postoperative iPTH was negatively correlated with postoperative serum P and 25(OH)vitD, and positively correlated with postoperative Ca and BTMs. The recipients without iPTH normalization, who accounted for 41.0% of all KTRs, presented with higher Ca, lower P, higher BTMs, advanced age, and a higher prevalence of preoperative parathyroid hyperplasia. CONCLUSIONS: MBD persisted after KT, showing a close relationship with hyperparathyroidism, high bone turnover, and glucocorticoid accumulation.