Hematopoietic System



Anemia is a nearly universal finding in patients with advanced renal disease. The etiology of the anemia is multifactorial. Red blood cell produc­tion is decreased owing to the lack of erythro­poietin production by the kidney, the presence of products retained in uremia which inhibit erythropoiesis, and fibrosis of the bone marrow. Red blood cell loss may be accelerated owing to the presence of uremic gastroenteritis and the disor­dered function of platelets. The anemia may be exacerbated by associated dietary limitations or malabsorption of essential foodstuffs required for red cell production, such as folic acid and iron.

Total white blood cell counts are normal to low in ESRD. Some patients manifest poor polymor­phonuclear leukocyte chemotaxis. Although not present in all ESRD patients, blunted production of antibodies and/or cellular immune responsivity is present in a significant number of such patients. The nature of the defects in white blood cell func­tion are not known with certainty but appear to include both an inherent defect in the cells them­selves and a response to a circulating factor. These defects in white blood cell function, in conjunc­tion with other factors, may provide an explana­tion for the findings that infections are a common cause of death in ESRD patients.

Platelet counts are normal in patients with ad­vanced renal disease, but qualitative defects in platelet function have been well-documented. Abnormalities in activity of clotting factors and in factors mediating the bleeding time have been described in ESRD patients. The abnormalities of hemostasis are not totally reversed by dialysis and may contribute to the frequent findings of gas­trointestinal blood loss and subcutaneous he­matomas in patients with ESRD. The defects in hemostasis are also important considerations in the evaluation of an ESRD patient who requires surgery.