The blood in systemic disorders

The high rate of proliferation required of the bone marrow renders it highly susceptible to the influence of external factors. Anaemia is the most common haematological abnormality seen in systemic disorders. In the anaemia of chronic disease, erythropoietin production is reduced and proliferation of erythroid progenitor cells is also impaired; this anaemia can generally be alleviated by correction of the underlying disease process. The status of the endocrine system must always be considered in evaluation of a normocytic, normochromic anaemia. Anaemia in infection can be due to host or parasite factors or to the treatment administered. Anaemia due to malignant disease responds to erythropoietin therapy in many cases; failure to respond is a poor prognostic sign.