MO952EFFECT OF KIDNEY TRANSPLANTATION ON PARATHYROID GLANDS FUNCTION
Authors: Ivanova Maria , Vetchinnikova Olga , Vatazin Andrey 
Published: May 2021

Abstract

Background and Aims
The normalization of the function of the parathyroid glands after successful kidney transplantation does not occur in all patients. The aim of our study was to determine of parathyroid function, patient factors that would be predictive of achieving a normal serum PTH in the first months after surgery and prevalence of hyperparathyroidism (HPT) in patients after kidney transplantation (KT) at various stages of the post-transplant period.

Method
The observational cross-retrospective study included 230 kidney graft recipients. Inclusion criteria: the duration of the post-transplant period is more than 12 months and stable kidney transplant function for 6 months. The median of the pre-transplant stage was 18 months (Q1-Q3: 9; 35), post-transplant period - 42 months (Q1-Q3: 21; 73). Serum concentrations of parathyroid hormone (PTH), calcium, phosphorus, total alkaline phosphatase activity, albumin, and creatinine were determined using standard methods. HPT was diagnosed with PTH&gt;130 pg/ml. Retrospective analysis of parameters in three months after surgery it was performed in 197 patients. Estimated glomerular filtration rate (eGFR) was calculated using the CKD-EPI formula, stratification of chronic kidney disease (CKD) stages was carried out according to the eGFR.

Results
Patients had different kidney transplant function: eGFR 117-15 ml/min, median 51 (Q1-Q3: 39;65): CKD 1(КT) st. was in 3.5%, CKD 2(КT) st. - in 33.9%, CKD 3(КT) st. - in 49.1% and CKD 4(КT) st. – in 13.5% patients. Serum PTH levels were 27-670 pg/ml, median 120 pg/ml (Q1-Q3: 87; 182). The median PTH of blood in patients was 99 pg/ml (Q1-Q3: 76; 120), 98 pg/ml (Q1-Q3: 79; 123), 120 pg/ml (Q1-Q3: 89; 180) and 267 pg/ml (Q1-Q3: 170; 328), respectively, with CKD 1(КT), CKD 2(КT), CKD 3(T) and CKD 4(КT) st. The frequency of HPT was 38.7%: 19.8% in patients with eGFR≥60 ml/min, 38.1% and 93.5% in patients with CKD 3(КT) and CKD 4(КT) st. (p&lt;0.001) (Fig. 1). HPT was equally frequently diagnosed in the second, third, fourth and fifth years after kidney transplantation and amounted to 30.3% in the first five years. In patients with a post-transplant period of more than 5 years, HPT was 54.7% (p&lt;0.001). In the same group, the proportion of patients with eGFR&lt;60 ml/min was also higher - 55.5% (p=0.002) (Fig. 2). An inverse relationship was established between serum PTH and eGFR and a direct relationship between serum PTH and serum creatinine (p&lt;0.001). A retrospective analysis showed that 3 months after kidney transplantation, the median PTH was 178 pg/ml (Q1-Q3: 120; 250), HPT was recorded in 65.5% of patients. Serum PTH decreased by 6-92%, median 50%. Kidney graft function was worse in patients with a decrease in serum PTH ≤50% (n = 100) versus patients with a decrease in serum PTH &gt;50% (n = 97). Minimal blood creatinine was recorded in the early postoperative period, respectively, on (median) 7 and 5 days (p = 0.015), the median eGFR by the end of the third month was 59 and 63 ml/min, respectively (p=0.044). We found that preoperative PTH&gt;585 pg/ml (p&lt;0.0001 OR 2.93 95% CI 1.78; 5.05), delayed kidney graft function (p=0.005 OR 1.57 95% CI 1.58; 9.87), and eGFR&lt;60 ml/min (p&lt;0.0005 OR 2.01 95% CI 1.36; 3.09) were predictive of HPT in patients in the early stages after kidney transplantation.

Conclusion
Hyperparathyroidism in patients after kidney transplantation continues to be an ongoing problem. It occurs in a third of patients in the first five postoperative years and in half patients in subsequent years. Preoperative secondary hyperparathyroidism, delayed and suboptimal kidney graft function prevent the restoration of parathyroid glands function after kidney transplantation.