Hyperparathyroidism (HPT) with hypercalcemia, often deemed irreversible and detrimental to graft survival post-kidney transplantation (KT), prompts pre-transplant parathyroidectomy in hypercalcemic patients. In this retrospective analysis of 1212 kidney transplant recipients (KTRs) between 2006 and 2019, the incidence and effect of persistent HPT and hypercalcemia on graft and patient survival, and risk factors for persistence were analyzed until 60 months of follow up (FU). At KT, 5.7% (n = 69) had no HPT, 32.7% (n = 396) had HPT without hypercalcemia and 37.0% (n = 448) had HPT with hypercalcemia. At 2 years FU, 26.4% (n = 320) of patients had no HPT and 6% (n = 73) had HPT with hypercalcemia. Dialysis and dialysis duration were linked to HPT development, while dialysis, KT waiting time and donor type correlated with persisting hypercalcemia after KT. KTRs with normalized PTH and recovered hypercalcemia had improved death-censored graft survival (p < 0.001) and overall patient survival (p < 0.001). HPT with hypercalcemia is frequent at time of KT with normalization of PTH and calcium in a substantial proportion of patients after a KT. These findings question the routine pre-KT parathyroidectomy for suspected parathyroid autonomy. Persisting HPT, especially with hypercalcemia, adversely affects graft and patient survival, suggesting the need for more aggressive treatment of HPT, especially in cases of persisting hypercalcemia.

Disturbances in calcium-phosphate homeostasis are common after kidney transplantation. We aimed to assess the relationship between deregulations in plasma calcium and phosphate over time and mortality and death-censored graft failure (DCGF). In this prospective cohort study, we included kidney transplant recipients with ≥2 plasma calcium and phosphate measurements. Data were analyzed using time-updated Cox regression analyses adjusted for potential confounders including time-updated kidney function. We included 2769 patients (mean age 47 ± 14 years, 42.3% female) with 138 496 plasma calcium and phosphate levels (median [IQR] 43 [31-61] measurements per patient). During follow-up of 16.3 [8.7-25.2] years, 17.2% developed DCGF and 7.9% died. Posttransplant hypercalcemia was associated with an increased risk of mortality (1.63 [1.31-2.00], p < 0.0001), but not with DCGF. Hyperphosphatemia was associated with both DCGF (2.59 [2.05-3.27], p < .0001) and mortality (3.14 [2.58-3.82], p <  .0001). Only the association between hypercalcemia and mortality remained significant in sensitivity analyses censored by a simultaneous eGFR <45 mL/min/1.73 m2 . Hypocalcemia and hypophosphatemia were not consistently associated with either outcome. Posttransplant hypercalcemia, even in the presence of preserved kidney function, was associated with an increased mortality risk. Associations of hyperphosphatemia with DCGF and mortality may be driven by eGFR.

Tertiary hyperparathyroidism is a common cause of hypercalcemia after kidney transplantation (KT) and has been associated with renal dysfunction, bone mineral density loss, and increased risk of fracture and cardiovascular events. In a previous 12-month clinical trial, we demonstrated that subtotal parathyroidectomy was more effective than cinacalcet for controlling hypercalcemia. In the current study, we retrospectively evaluate whether this effect is maintained after 5 years of follow-up. In total, 24 patients had data available at 5 years, 13 in the cinacalcet group and 11 in the parathyroidectomy group. At 5 years, 7 of 11 patients (64%) in the parathyroidectomy group and 6 of 13 patients (46%) in the cinacalcet group (P = .44) showed normocalcemia. However, recurrence of hypercalcemia was only observed in the cinacalcet group (P = .016). Subtotal parathyroidectomy retained a greater reduction in intact parathyroid hormone (iPTH) compared with cinacalcet group. No differences were observed in kidney function and incidence of fragility fractures between both groups. Cinacalcet was discontinued in 5 out of 13 patients. In conclusion, in kidney transplant patients with tertiary hyperparathyroidism recurrence of hypercalcemia after 5-year follow-up is more frequent in cinacalcet than after subtotal parathyroidectomy.

Persistent hyperparathyroidism (HPT) after kidney transplantation (KTx) is associated with hypercalcemia, hypophosphatemia and abnormally high levels of parathyroid hormone (PTH). In this randomized trial, cinacalcet was compared to placebo for the treatment of hypercalcemia in adult patients with persistent HPT after KTx. Subjects were randomized 1:1 to cinacalcet or placebo with randomization stratified by baseline corrected total serum calcium levels (≤11.2 mg/dL [2.80 mmol/L] or >11.2 mg/dL [2.80 mmol/L]). The primary end point was achievement of a mean corrected total serum calcium value<10.2 mg/dL (2.55 mmol/L) during the efficacy period. The two key secondary end points were percent change in bone mineral density (BMD) at the femoral neck and absolute change in phosphorus; 78.9% cinacalcet- versus 3.5% placebo-treated subjects achieved the primary end point with a difference of 75.4% (95% confidence interval [CI]: 63.8, 87.1), p<0.001. There was no statistical difference in the percent change in BMD at the femoral neck between cinacalcet and placebo groups, p=0.266. The difference in the change in phosphorus between the two arms was 0.45 mg/dL (95% CI: 0.26, 0.64), p<0.001 (nominal). No new safety signals were detected. In conclusion, hypercalcemia and hypophosphatemia were effectively corrected after treatment with cinacalcet in patients with persistent HPT after KTx.