MO541: Secondary Hyperparathyroidism Influence on Parathyroid Hormone Levels After Kidney Transplantation

Abstract

Abstract BACKGROUND AND AIMS Optimal parathyroid hormone (PTH) control in patients before kidney transplantation (KT) might decrease the subsequent risk of parathyroid hyperplasia and hyperparathyroidism (HPT) after surgery. We evaluated the patient characteristics and HPT markers control before and over the first post-transplant year. METHOD We studied 210 patients (107 women, 103 men and age 45 ± 9 years) with end-stage renal failure (ESRF). All patients underwent primary KT. The duration of the pre-transplant period ranged from 0 to 158 months (median 19). The determination of HPT markers was carried out before 3 and 12 months after KT. The target PTH after KT was considered to be 130 pg/mL. Serum concentrations of PTH, calcium, phosphorus, total alkaline phosphatase activity, albumin and creatinine were determined using standard methods, estimated glomerular filtration rate (eGFR) was calculated using the CKD-EPI formula and stratification of chronic kidney disease stages was carried out according to the eGFR. RESULTS Patients were divided into two groups based on PTH before KT. In the first group were 63 patients with PTH > 585 pg/mL (median 866, Q1–Q3: 667; 1078), in the second group there were 147 patients with PTH 130–585 pg/mL (median 300, Q1–Q3: 225; 400). Patients with secondary HPT versus target PTH group had long duration of dialysis therapy (27 months versus 15 months; P = 0.005), frequency of hyperphosphatemia (87% versus 57%; P < 0.001) and increased activity of blood alkaline phosphatase (21% versus 4%; P < 0.001). Initial renal transplant function was the same in both groups: acute tubular necrosis amounted to 57% and 46% respectively (P = 0.07), duration of acute tubular necrosis 2 and 0 days respectively (P = 0.087). Three months after kidney transplantation in the first group median blood PTH decreased to 247 pg/mL (Q1–Q3: 163; 452), the prevalence of PTH > 130 pg/mL had 88% patients, in the second group median blood PTH decreased to 150 pg/mL (Q1–Q3: 120; 210), the prevalence of PTH > 130 pg/mL had 59% patients (P < 0.001). Hypercalcemia was in 13% patients of first group and 0 in second group (P < 0.001). Serum creatinine and eGFR did not differ and amounted respectively to 114 (Q1–Q3: 86; 150) and 110 (Q1–Q3: 80; 136) μmol/L (ns), 60 (Q1–Q3: 45; 80) and 60 (Q1–Q3: 49; 80) mL/min (ns). The ratio of stages of chronic kidney disease was the same (Figure 1). A total of 12 months after KT the blood level PTH was 180 (Q1–Q3: 95; 247) and 106 (Q1–Q3: 88; 125) pg/mL (P = 0.004), the prevalence of PTH > 130 pg/mL had 54% and 15% (P < 0.001) patients respectively. Kidney transplant function did not differ as well as after 3 months (median serum creatinine 120–121 μmol/L, eGFR 55 and 55 mL/min). In the post-transplant period, patients of the first group were more often prescribed vitamin D preparations and its analogues, five were treated with cinacalcet due to hypercalcemia and seven underwent parathyroidectomy after 1.5–2.5 years. CONCLUSION Secondary HPT before KT predicted a higher PTH level in the first year after surgery. Patients with ESRF who are on the waiting list for KT need careful monitoring of blood PTH and adequate treatment of secondary HPT.