High Plasma Ionized Calcium with Normal PTH and Total Calcium Levels in Normal-Function Kidney Transplant Recipients

Abstract

Hypercalcemia is a postrenal transplant complication. We found a high frequency of elevated plasma ionized calcium values (65.8%) in 41 normal-function renal graft recipients. In 8 patients increased free calcium was associated with high PTH levels, whereas in 19 PTH was not increased but free calcium was high. In the other 14 patients both free calcium and PTH were in the normal range. The mean transplant duration was different in the three groups: shorter in high PTH patients, longer in normal free calcium patients, intermediate in normal PTH and high free calcium patients. Our findings confirm that a condition of hyperparathyroidism persists in the first post-transplant period, and suggest that this complication evolves towards normalization of the blood chemistry values, passing through a condition of inappropriate PTH secretion with elevated plasma free calcium which in this period is the only marker of parathyroid hyperfunction.

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

“…Comparable studies are scarce in literature. 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).…”

Persistent secondary hyperparathyroidism after renal transplantation in children

“…In adult renal transplant recipients, persistent high serum PTH levels are thought to result in hypercalcemia [9,17] and hypophosphatemia [10]. In our study, hypercalcemia after transplantation was seen in 28% and 23% at 6 months and 12 months, respectively.…”

Endocrine Alterations in Kidney Transplant Patients

“…57], hypercalciuria [13], hypophosphataemia with hyperphosphaturia [52], and subnormal in testinal calcium absorption [13] have been reported. Persistent secondary hyperpara thyroidism may be normo-or hypercalcaemic [47,[51][52][53]. Reduced phosphate reabsorption in renal tubules seems not to be related or predominantly related to PTH af ter renal transplantation [52], Unexpectedly, in some KTP normal plasma PTH and total calcium levels in the presence of highly ion ized calcium have been reported [51].…”

“…Persistent secondary hyperpara thyroidism may be normo-or hypercalcaemic [47,[51][52][53]. Reduced phosphate reabsorption in renal tubules seems not to be related or predominantly related to PTH af ter renal transplantation [52], Unexpectedly, in some KTP normal plasma PTH and total calcium levels in the presence of highly ion ized calcium have been reported [51]. Thus, it seems that hyperparathyroidism may per sist during the first post-transplant period and that this complication evolves towards normalization of the blood chemistry values passing through a period of inappropriate PTH secretion with elevated ionized calcium [51], The incidence of bone abnormalities during the post-transplant period does not only depend upon the functional quality of the graft, but also upon the degree of phos phate depletion, the amount of total gluco corticoids administered, and the nutritional and vitamin D status before and after trans plantation.…”

“…Reduced phosphate reabsorption in renal tubules seems not to be related or predominantly related to PTH af ter renal transplantation [52], Unexpectedly, in some KTP normal plasma PTH and total calcium levels in the presence of highly ion ized calcium have been reported [51]. Thus, it seems that hyperparathyroidism may per sist during the first post-transplant period and that this complication evolves towards normalization of the blood chemistry values passing through a period of inappropriate PTH secretion with elevated ionized calcium [51], The incidence of bone abnormalities during the post-transplant period does not only depend upon the functional quality of the graft, but also upon the degree of phos phate depletion, the amount of total gluco corticoids administered, and the nutritional and vitamin D status before and after trans plantation. Plasma PTH levels during the post-transplant period are not predictive for the occurrence of bone complications in KTP [48], The kind of immunosuppressive therapy (azathioprine or CS-A) does not seem to influence markedly the incidence of persistent hyperparathyroidism during the post-transplant period [unpublished own data].…”