Transient impairment of tubular reabsorption of calcium (TRCa) after renal transplantation.

TRCa calculations (using the values of plasma ultrafiltrable Ca and urinary Ca) revealed impaired renal Ca handling in 14/32 patients with transplanted kidneys. TRCa improved in relationship with the increment in renal transplant function, and was within the normal range in all patients with GFR above 50 ml/min. There was a positive correlation between serum Ca and TRCa; hypocalcaemia was found in 9 patients and hypercalcaemia in 3. In the majority of hypocalcaemic patients TRCa impairment was discovered, however, pathologically decreased serum Ca values were found in only one half of the patients with impaired TRCa. In most hypocalcaemic patients the concomitant renal transplant insufficiency, hyperphosphataemia and/or insufficient dietary Ca intake seemed likely to have contributed to serum Ca depletion.