#4670 HYPERPARATHYROIDISM DURING 1ST YEAR OF RENAL TRANSPLANT IS ASSOCIATED WITH LONG TERM GRAFT LOSS

Abstract

Abstract Background and Aims Persistent hyperparathyroidism (HPT) is a frequent problem, especially during the first year after Renal transplant (RTx). We aimed to evaluate the possible association between parathormone (PTH) levels during 1st year of RTx and long-term graft loss (GL) in RTx patients (RTx-p). Method We retrospectively evaluated 871 RTx-p, transplanted in our unit from 2004 to 2020. We measured main renal function and mineral metabolism parameters at 1 month (T1), 6 months (T6) and 12 months (T12) after RTx. Renal outcome was intended as GL during the global follow-up (FU) of 103±60 mths. Results Mean age at RTx was of 49+13 yrs and 58% of RTx-p were male. Most of the RTx-p were on hemodialysis (HD) before RTx (77%) with a mean dialysis vintage of 53+52 months. Most of our cohort (84%) received a kidney from a deceased donor. HPT was highly prevalent during the 1st year of FU; at T1 79% of RTx-p were HPT, of which 63% had secondary HPT (SHPT) and 16% had tertiary HPT (THPT). Comparable prevalence was observed at T6 (HPT 80%; SHPT 64%; THPT 16%) and at T12 (HPT 77%; SHPT 62%; THPT 15%). A strong significant correlation was found between HPT type and GL at every time point [T1 GL: no HPT 6%, SHPT 11% THPT 24%, p<0.0001 - T6 GL: no HPT 9%, SHPT 9% THPT 22%, p<0.0001 - T12 GL: no HPT 8%, SHPT 9% THPT 21%, p = .008]. Moreover, PTH levels at T1 (GL+: 90.3 [50.6-165.6] vs. GL-: 61.7 [37.4-98.8] p<0.0001), at T6 (GL+: 83.6 [47.1-152.4] vs. GL-: 56.1 [38.3-89.7] p<0.0001) and at T12 (GL+: 69.8 [44-121.9] vs. GL-: 54.6 [36.4-84.1] p = 0.008) were significantly correlated to GL. PTH levels at T1 and T6 were associated with long-term GL [T1, OR: 3.3 (1.3-8.1), p = 0.01 - T6, OR: 3.9 (1.7-9.2), p = 0.001]. Then we considered PTH levels as mean exposure during the first year. Mean PTH exposure alone was strongly associated with GL [OR: 5.7 (2.7- 11.9), p<0.0001]. A multivariate logistic regression analysis was also performed. In the model, we considered 1st year mean PTH exposure and the main factors associated with GL (pre-RTx dialysis vintage, 1st year rejection, T12 uric acid, T12-Proteinuria and T12-MDRD). Mean PTH exposure remained strongly and independently associated with long-term GL (OR 3.1 [1.4-7.1], p = 0.008). We finally performed a ROC curve to calculate the best 1st-year mean PTH cut-off to predict long-term GL. AUC was 0.658, with a p<0.0001. Using Youden index we identified the best mean PTH cut off to be 88.6 pg/ml. Conclusion In our cohort of 871 RTx-p, the prevalence of HPT during the first year of RTx is quite high. High PTH levels during 1st year of RTx were independently associated with long-term GL. HPT might be considered a therapeutic target to prevent long-term graft failure.