SERUM ERYTHROPOIETIN AND RETICULOCYTE MATURITY INDEX AFTER RENAL-TRANSPLANTATION - A PROSPECTIVE LONGITUDINAL-STUDY

Improvement in erythropoiesis following renal transplantation (RT) was assessed in 74 consecutive patients by serial measurements of serum e rythropoietin (EPO), hematocrit, absolute reticulocyte count (ARC) and serum creatinine during the first month after RT. The reticulocyte ma turity index (RMI) which provides an objective measure of red-cell mat urity was assessed in 31 patients by flow cytometry using thiazole ora nge. In group I (n = 39) with immediate graft function, EPO levels inc reased rapidly from day 2 and remained elevated at the plateau between two and three times the upper limit of normal during the first 2 mont hs. In group II (n = 29) with delayed graft function, EPO levels incre ased gradually from day 10 when renal function improved significantly. No particular significant biphasic pattern of secretion was detected in group I or II. In both groups, hematocrit rose to over 35% approxim ately 3 months after RT. In a third group (n = 6) with immediate posto perative acute blood loss and severe anemia, a hematocrit fall was fol lowed by a steep increase in EPO levels with a negative correlation be tween hematocrit and EPO levels during the first 4 days. During acute rejection, EPO diminished significantly by more than 50% either on the day of diagnosis or on the following days in 8 patients. RMI increase d by 25% over the pretransplantation values by 7 days on average befor e the ARC rose. Thus the RMI seems to be an early sensitive predictor of erythropoiesis after RT. EPO response after RT depends on graft fun ction, and the early transient increase in EPO observed in patients wi th acute blood loss may explain the apparent biphasic response previou sly reported.