Underrecognition and Underestimation of Disturbances in Calcium-Phosphate Balance in Kidney Transplant Recipients

Disturbances in mineral metabolism, namely chronic kidney disease-metabolic bone disease, became more profound with impairment of renal function. The aim of the study was to assess how often calcium, phosphate, alkaline phosphatase, and parathyroid hormone (PTH) were measured in kidney transplant recipients relative to hemodialyzed patients. In addition, prevalence of hypercalcemia defined as calcium concentration over 10.5 mg/dL was assessed.

We studied 200 kidney allograft recipients and 100 hemodialyzed patients. Calcium, phosphate, alkaline phosphatase, 25-hydroxy vitamin D, and PTH were obtained from outpatient charts.

All the studied parameters were available in 100% of the hemodialyzed patients. In kidney allograft recipients, calcium and phosphate levels were available in 80%, alkaline phosphatase activity was available in 40%, PTH was available in less than 10%, and vitamin D was available in 1%. Hypercalcemia was present in 10% of hemodialyzed patients and in 5% of kidney allograft recipients. Vitamin D analogue was administered to 98% of hemodialyzed patients, whereas vitamin D was administered to 28% of kidney allograft recipients, particularly those with impaired kidney function. In conclusion, calcium and phosphate are seldom assessed on an outpatient basis in kidney allograft recipients, making the diagnosis and treatment of secondary hyperparathyroidism in this population difficult. Care of kidney transplant recipients could be substantially improved, particularly in regard to chronic kidney disease-metabolic bone disease, when regular check-ups for calcium-phosphate balance are implemented and proper treatment could be introduced to prevent further chronic kidney disease-metabolic bone disease.