Evolution of secondary hyperparathyroidism one year after successful renal transplantation

Background: The natural history of parathyroid function after successful renal transplantation (Tx) as well as the factors predisposing to persistent secondary hyperpathyroidism (sHPT) are not well established, whereas regression of sHPT is not always observed and depends on renal graft function. The aim of the present study was to evaluate the post-Tx natural history of parathyroid function in patients with a well functioning renal graft. Patients and Methods: One hundred and five (105) patients, which underwent successful renal transplantation, were studied. Sixteen (16) patients had a history of previous parathyroidectomy for severe HPT. Results: Parathyroid hormone (PTH) mean value presented a significant fall from 373.2 +/- 418 to 128 +/- 121 pg/ml (p<0.001) at 12 months post-Tx. Pre-Tx PTH levels were significantly correlated with 12 months post-Tx levels (r=0.46, p<0.001). Serum calcium did not present significant alterations, whereas serum phosphorus decreased significantly, since the third month post-Tx from 5.9 +/- 1.67 mg/dl to 3.2 +/- 0.75 mg/dl (p<0.001). Renal graft function remained well preserved and mean serum creatinine was 1.59 +/- 0.44 mg/dl at the 12(th) month post-Tx. Eighteen (18) patients presented severe HPT (PTH > 800 pg/ml) at the time of transplantation. In this group of patients, PTH was also significantly decreased, but remained in abnormal levels (PTH > 100 pg/ml) after 12 months post-Tx in 6 cases. Conclusions: These results suggest an improvement of parathyroid function as measured by PTH levels, during the first year after successful renal transplantation in patients with mild or moderate sHPT. Twelve months' PTH levels depend on pre-Tx levels. However severe pre-existing sHPT may persist even after one year post-Tx in a significant number of patients. Hippokratia 2011; 15 (Suppl 2): 30-32