Predicting the ideal serum creatinine of kidney transplant recipients by a simple formula based on the balance between metabolic demands of recipients and renal mass supply from donors.

Serum creatinine (Scr) is the most frequently used test to estimate graft function after kidney transplantation. Our previous study demonstrated that the independent predictors of recipient posttransplantation Scr included the ratio of graft weight to recipient body weight, the ratio of graft weight to recipient body surface area (BSA), and the ratio of graft weight to recipient body mass index (BMI). A prospective analysis about the impact of the balance between metabolic demands and renal supply on posttransplantation Scr of recipients was previously reported. We plotted the scatter graph using the X-axis as the independent predictors of Scr by linear regression and the Y-axis as the recipient Scr. To generate the predictive formula of Scr, we calculated a fit of the line of plotted cases using a linear regression method with 2 regression lines for prediction of the upper and lower 95% confidence intervals. Each line was converted into a predictive formula: Scr = -0.0033* (Graft weight(g)/Recipient BSA(m2))+1.75. Under 95% confidence, the Scr ranges from -0.0033* (Graft weight(g)/Recipient BSA(m2))+1.07 to -0.0033* (Graft weight(g)/Recipient BSA (m2))+2.44. Scr = -0.1049* (Graft weight(g)/Recipient body weight(kg))+1.72, which ranges from -0.1049* (Graft weight(g)/Recipient body weight(kg))+1.06 to -0.1049* (Graft weight(g)/Recipient body weight(kg))+2.37. Scr = -0.0158* (Graft weight(g)/Recipient BMI(kg/m2))+1.56, which ranges from -0.0158* (Graft weight(g)/Recipient BMI(kg/m2))+0.75 to -0.0158* (Graft weight(g)/Recipient BMI(kg/m2))+2.26. Prediction of posttransplantation Scr may be achieved by measuring graft weight as well as recipient weight and height. When recipient Scr is significantly higher than that predicted by the formula, a clinician should suspect an underlying graft injury.