Erythropoietin deficiency and relative resistance cause anaemia in post-renal transplant recipients with normal renal function

BACKGROUND: Following successful renal transplantation, blood erythropoietin(Epo) levels peak in two phases during the first 2–3 months,and blood haemoglobin/haematocrit (Hb/Hct) levels are restoredto normal in a period of 2–6 months. However, some transplantrecipients continue to remain anaemic in spite of normal graftfunction and in the absence of recognizable causes. The roleof endogenous Epo production in the causation of anaemia insuch patients is poorly understood and has been investigatedin this study. METHODS: Twenty-three post-renal transplant recipients with stable normalrenal function were studied. Eleven of these patients had normalHb/Hct levels (group 1) and served as control for the rest 12patients with anaemia (group 2). Patients included in group2 had no readily recognizable cause for their anaemia. Otherlaboratory and clinical findings were similar in both groups.Patients with erythrocytosis were excluded. Serum Epo levelswere measured in all patients. Five patients in group 2 weretreated with recombinant human erythropoietin (rHuEpo) and theirerythropoietic response was assessed. rHuEpo was discontinuedwhen the target Hb/Hct levels (lowest normal range) were achievedand the patients were followed up for a further period of 9–12months. RESULTS: Five patients in group 1 had normal expected serum Epo levelswhereas the other six patients had inappropriately high serumEpo levels with respect to their Hb/Hct status suggestive ofrelative ‘Epo resistance’. Serum Epo levels in allpatients except two in group 2 were low indicative of ‘Epodeficiency’. The two exceptional patients in group 2 hadhigher serum Epo levels in the presence of anaemia suggestiveof relative ‘Epo resistance’. All five patients treated with rHuEpo responded adequately byachieving normal Hb/Hct levels. Three of them were originally‘Epo deficient’ and they reached target Hb/Hct levelsin a mean period of 4 weeks, requiring a mean cumulative rHuEpodose of 428.3 units/kg. The other two patients with higher initialserum Epo levels, and considered to be ‘Epo resistant’,required an average of 11 weeks of treatment and a mean cumulativerHuEpo dose of 1582.5 units/ kg, indicating an increased Epodemand. On cessation of therapy the Hb/Hct levels fell in allfive patients to pretreatment values in 6 months. CONCLUSIONS: There are important variations in the endogenous Epo productionin renal transplant patients with normal renal function, thecause of which is not clear. Epo deficiency and relative Eporesistance play a causative role for anaemia in some post-renaltransplant recipients with stable normal renal function. Theyrespond adequately to rHuEpo administration.