New insights into the thrombopoietic status of patients on dialysis through the evaluation of megakaryocytopoiesis in bone marrow and of endogenous thrombopoietin levels

The thrombopoietic status of patients with uremia remains unclear. This iss ue was addressed with particular reference to marrow megakaryocytopoiesis a nd endogenous thrombopoietin (TPO) levels. A study was conducted in 114 pat ients on hemodialysis, 43 patients on continuous ambulatory peritoneal dial ysis, and 48 age-matched controls. Reticulated platelets, a marker of marro w megakaryocytopoiesis, were measured by flow cytometry, Serum TPO levels, platelet-associated IgG (PAIgG) levels, and hepatitis C virus (HCV) antibod y titers were also measured by enzyme-linked immunosorbent assay. Circulati ng and reticulated platelet counts were significantly lower in the patients on dialysis than in the controls. Thrombocytopenia (less than 150 x 10(9)/ L) was most frequent in the HCV-positive hemodialysis patients, who had a h igher incidences and higher PAIgG titers. The following results were obtain ed in the HCV-negative dialysis patients: (1) platelet counts chronological ly decreased with years on hemodialysis; (2) platelet counts were associate d with the reticulated platelet counts; (3) serum TPO levels were significa ntly elevated in the dialysis patients, responding to the decrease of retic ulated platelets; (4) hematocrits had a positive correlation with serum TPO levels, and serum TPO levels were significantly higher in the patients on hemodialysis who did not require recombinant human erythropoietin therapy t han in the other patients. In conclusion, thrombocytopenia is a frequent fi nding in patients on dialysis, The failure of megakaryocyte production coul d be the principal cause of the platelet reduction, and the peripheral dest ruction and sequestration of platelets may be concomitantly involved. Eleva tion of serum TPO may in part serve as an aid to erythropoiesis in dialysis patients. (C) 2001 by The American Society of Hematology.