Postprandial increase in serum creatinine in renal transplant recipients

Daily variation in serum creatinine and the effect of a protein load was studied in 18 patients with renal transplants and in 10 healthy controls. Serum creatinine was analyzed both with a standard Jaffe method and with a specific HPLC technique. Following a protein meal, a 30% increase in serum creatinine levels was noted in both groups, but the rise in absolute terms was more prominent among the transplanted patients. Urinary excretion of creatinine did not increase in the transplanted group, indicating a reduced ability to deal with the surplus creatinine in the protein meal. It is concluded that serum creatinine levels are diet-dependent and that this variation is more pronounced when renal function is reduced. Standardized blood sampling is important when following serum creatinine in renal transplant recipients from one day to the next.