Kidney Injury Molecule-1 Correlates With Kidney Function in Heart Allograft Recipients

Serum creatinine and estimated glomerular filtration rate (eGFR) (24 hours creatinine clearance, Modification of Diet in Renal Disease, Chronic Kidney Disease Epidemiology Collaboration, Cockcroft-Gault formulae), and urinary kidney injury molecule-1 (KIM-1), were evaluated in 111 heart allograft recipients on therapy with a calcineurin inhibitor, mycophenolate mofetil or azathioprine plus prednisone. KIM-1 was assessed using commercially available assay. Normotensive heart allograft recipients showed significantly lower KIM-1 values than hypertensive subjects. Urinary KIM-1 was significantly higher among New York Heart Association class III versus I and II patients. Upon univariate analysis, urinary KIM-1 strongly correlated with serum creatinine (r = .54) and eGFR (r = .66) but only weakly with other parameters. It was not related to cystatin C. Upon multiple regression analysis, the best predictor of urinary KIM-1 was eGFR (beta -0.56), explaining 76% of KIM-1 concentrations. Even a successful heart transplantation is associated with kidney injury as reflected by elevated urinary KIM-1 and reduced eGFR. Therefore, KIM-1 needs to be investigated as a potential early marker for impaired kidney function/kidney injury, especially in patients with other risk factor for kidney damage, for example, hypertension or congestive heart failure.