Calcium Metabolism in the Early Posttransplantation Period

Abstract

Background and objectives: Information on the time course of serum calcium levels after renal transplantation is scanty, especially in the early posttransplantation period. Both the abrupt cessation of calcium-containing phosphorus binders and vitamin D (analogs) at the time of surgery and the recovery of renal function may be hypothesized to affect serum calcium levels in this period.Design, setting, participants, & measurements: In this prospective observational study, biointact parathyroid hormone, calcidiol, calcitriol, calcium, and phosphorus levels were monitored in 201 renal transplant recipients at the time of transplantation and 3 mo thereafter. In addition, the serum calcium nadir and peak in each individual patient within this time frame were identified and the urinary fractional calcium excretion was determined at month 3.Results: Serum calcium levels followed a biphasic pattern with a significant decline during the first postoperative week, followed by a significant increase. High pretransplantation parathyroid hormone levels protect against hypocalcemia within the first postoperative week but put patients at risk for hypercalcemia later. These complications, occurring in 41 and 14% of the patients, respectively, most probably reflect inappropriate calcium release from the skeleton, rather than inappropriate renal calcium handling.Conclusions: Our data indicate that both hypo-and hypercalcemia are prevalent in the early posttransplantation period. Pretransplantation parathyroid function is an important predictor of posttransplantation calcium levels.

Measuring Total Blood Calcium Displays a Low Sensitivity for the Diagnosis of Hypercalcemia in Incident Renal Transplant Recipients

“…Vezzoli et al (20) reported iCa levels exceeding 1.29 mmol/L in 27 of 41 renal transplant recipients, which represent a prevalence rate that is close to ours. Most studies assessing post-transplant calcium metabolism thus far analyzed uncorrected or albumin-corrected tCa levels and reported substantially lower prevalences of hypercalcemia (7)(8)(9)(10)(11)21,22). Also in this study, hypercalcemia, defined as tCa Ͼ10.3 mg/dl, was observed in only 13.1% of the patients.…”

“…We recently showed that serum Ca levels follow a biphasic pattern during the first 3 months after renal transplantation, with an immediate postoperative decline followed by a significant increase (7). Transient hypercalcemia is reported in 5 to 66% of renal transplant recipients (8 -11).…”

Surgical management of secondary hyperparathyroidism in chronic kidney disease—a consensus report of the European Society of Endocrine Surgeons

“…However, progressive renal dysfunction potentially due to consequences of persistent hyperparathyroidism was described in tertiary HPT patients [115] (EL 2). Moreover, medical treatment with cinacalcet [112] is often used after renal transplantation, despite lack of approval for this indication in many countries [116].…”

“…Patients should be operated after efficient vitamin D supplementation in order to avoid severe postoperative hypocalcaemia [115] (EL 3). However, hypercalcemia before PTX may prevent vitamin D supplementation in some.…”

Persistent hyperparathyroidism after kidney transplantation; updates on the risk factors and its complications

“…Reported risk factors for persistent HPT after kidney transplantation are shown in Box 2 (1,(17)(18)(19)(20)(21)(22). Persistent post-transplant HPT is thought to be primarily attributed to some degree of CKD and parathyroid gland hyperplasia retained by kidney-transplant patients (9,23).…”