Causes of hypercalcemia in renal transplant recipients: persistent hyperparathyroidism and others

Hypercalcemia is common in patients after kidney transplantation (KTx) and is associated with persistent hyperparathyroidism in the majority of cases. This retrospective, single-center study evaluated the prevalence of hypercalcemia after KTx. KTx recipients were evaluated for 7 years after receiving kidneys from living or deceased donors. A total of 301 patients were evaluated; 67 patients had hypercalcemia at some point during the follow-up period. The median follow-up time for all 67 patients was 62 months (44; 80). Overall, 45 cases of hypercalcemia were classified as related to persistent post-transplant hyperparathyroidism (group A), 16 were classified as “transient post-transplant hypercalcemia” (group B), and 3 had causes secondary to other diseases (1 related to tuberculosis, 1 related to histoplasmosis, and 1 related to lymphoma). The other 3 patients had hypercalcemia of unknown etiology, which is still under investigation. In group A, the onset of hypercalcemia after KTx was not significantly different from that of the other groups, but the median duration of hypercalcemia in group A was 25 months (12.5; 53), longer than in group B, where the median duration of hypercalcemia was only 12 months (10; 15) (P<0.002). The median parathyroid hormone blood levels around 12 months after KTx were 210 pg/mL (141; 352) in group A and 72.5 pg/mL (54; 95) in group B (P<0.0001). Hypercalcemia post-KTx is not infrequent and its prevalence in this center was 22.2%. Persistent hyperparathyroidism was the most frequent cause, but other important etiologies must not be forgotten, especially granulomatous diseases and malignancies.

高钙血症（Hypercalcemia）在肾移植（Kidney Transplantation, KTx）术后患者中较为常见，且多数病例与持续性甲状旁腺功能亢进相关。本项回顾性单中心研究旨在评估肾移植术后高钙血症的患病率。研究对象为接受活体或尸体供肾移植的肾移植术后患者，随访时长为7年。本研究共纳入301例患者进行评估，其中67例患者在随访期间的某一时间点出现高钙血症。67例高钙血症患者的中位随访时长为62个月（四分位间距：44~80个月）。总体而言，45例高钙血症被归类为移植术后持续性甲状旁腺功能亢进相关型（A组），16例归类为"移植术后一过性高钙血症"（B组），另有3例的病因继发于其他疾病（1例与结核病相关、1例与组织胞浆菌病相关、1例与淋巴瘤相关）。其余3例患者的高钙血症病因不明，目前仍在研究中。A组患者肾移植术后高钙血症的发病时间与其他组无显著差异，但A组高钙血症的中位持续时长为25个月（四分位间距：12.5~53个月），长于B组的12个月（四分位间距：10~15个月）（P<0.002）。肾移植术后约12个月时，A组患者的血清甲状旁腺激素中位水平为210pg/mL（四分位间距：141~352pg/mL），B组为72.5pg/mL（四分位间距：54~95pg/mL），组间差异具有统计学意义（P<0.0001）。肾移植术后高钙血症并非少见病症，本中心中其患病率达22.2%。持续性甲状旁腺功能亢进是最常见的病因，但也不可忽视其他重要致病因素，尤其是肉芽肿性疾病与恶性肿瘤。