Pretransplant serum FT3 levels in kidney graft recipients are useful for identifying patients with higher risk for graft failure

Objective End‐stage renal disease (ESRD) is a condition associated with thyroid disturbances both in function and morphology. Recent studies demonstrated that serum free triiodothyronine 3 (FT3) levels are negatively correlated with serum markers of inflammation and endothelial activation in patients with ESRD. However, no previous research evaluated serum thyroid function parameters in relation to kidney graft outcome, as we aim to do so in this study. Design Serum FT3, free thyroxine 4 (FT4) and TSH levels were measured before transplantation in 196 kidney graft recipients. Results The graft survival rate at 5 years for all patients was 92·3%. Kidney graft recipients with normally functioning grafts showed serum pretransplant thyroid parameters similar to patients who experienced graft failure. Life‐time analysis was performed after stratification of patients according to pretransplant serum FT3 levels < 3·1 pmol/l or > 3·1 pmol/l. A significantly different 5‐year death‐censored graft survival rate (93·9%vs. 76·5% for patients with normal or low FT3 levels, respectively; P < 0·01) and similar survival rate (death of patients with functioning grafts) (21·1%vs. 5·9%; P = 0·288) were observed. No similar feature was found for FT4 or TSH, suggesting that the effect is not related to hypothyroidism but rather dependent upon inappropriately low FT3 levels. Pretransplant serum FT3 levels were similar in patients who experienced early acute rejections as compared with nonrejector patients. Conclusions The results of this study demonstrate that among patients with ESRD undergoing kidney transplantation, those displaying lower pretransplant serum FT3 levels are at higher risk for subsequent graft failure. The demonstration of a predictive value of serum FT3 levels for graft survival suggests that measurement of pretransplant serum FT3 levels might represent a clinically useful parameter to identify patients with increased risk for graft failure.