Abnormalities of the formed elements of the blood, and of the clotting, fibrinolytic, and related systems, are very common in systemic lupus erythematosus (SLE). The major hematologic manifestations of SLE are anemia, leukopenia, thrombocytopenia, and the antiphospholipid syndrome (APS). These hematologic abnormalities may be a presenting manifestation of SLE, and can be a sign of disease activity if other possible causes are excluded. This topic review will provide an overview of these problems.
Anemia is a frequent occurrence in systemic lupus erythematosus (SLE), affecting most patients at some time in the course of their disease. Multiple mechanisms contribute to the development of anemia, including inflammation, renal insufficiency, blood loss, dietary insufficiency, medications, hemolysis, infection, hypersplenism, myelofibrosis, myelodysplasia, and aplastic anemia that is suspected to have an autoimmune pathogenesis [1-8].
Anemia of chronic inflammation — A frequent cause of anemia in SLE is suppressed erythropoiesis from chronic inflammation (anemia of chronic disease or anemia of chronic inflammation) . The anemia is normocytic and normochromic with a relatively low reticulocyte count. Although serum iron levels may be reduced, bone marrow iron stores are adequate, and the serum ferritin concentration is elevated. The major mediator of the anemia of chronic inflammation is hepcidin, a central regulator of iron homeostasis that inhibits the release of iron from macrophages and iron absorption in the small intestine. This results in iron-limited hematopoiesis. The mechanisms by which this anemia is produced by chronic inflammatory diseases are further discussed in detail elsewhere. (See "Anemia of chronic disease (anemia of [chronic] inflammation)".)
As in other chronic illnesses, serum erythropoietin levels may be inappropriately low for the degree of anemia. However, some of the apparent reduction in serum erythropoietin may be spurious; autoantibodies to erythropoietin may interfere with commercial laboratory testing .
Recommendations — In the absence of either symptoms attributable to anemia (eg, dyspnea on exertion, easy fatigability) or renal insufficiency (see 'Renal insufficiency' below), anemia of chronic inflammation does not require specific treatment.