Hematopoiesis

Hematopoiesis is the process by which the formed elements of the blood are regulated through a series of steps, beginning with the pluripotent stem cell. Once stem cells are committed to specific differentiated cell lineages, hematopoietic precursor cells come under increasing regulation by growth factors and hormones. The physiologic regulator of red cell (erythrocyte) production is the glycoprotein hormone erythropoietin, of which >90% is made in the kidney.

Anemia is a common complication of CKD, mainly due to the inability of the kidneys to secrete enough erythropoietin to stimulate adequate hematopoiesis. Additional factors that may cause or contribute to CKD-related anemia include iron deficiency, severe hyperparathyroidism,12 acute and chronic inflammatory conditions, aluminum toxicity, folate deficiency, shortened red blood cell survival, hypothyroidism, and hemoglobinopathies such as a-thalassemia.

hematopoiesis

CAUSES OF CANCER-RELATED ANEMIA

Neoplastic process: chronic anemia of cancer
Chemotherapy and radiation therapy
Intercurrent infections
Clonal disorders of hematopoiesis
Gastrointestinal blood loss
Autoimmune hemolysis
Microangiopathy
Excessive marrow fibrosis and displacement
Iron, folate, vitamin B12 deficiency
Renal impairment
Reprinted with permission from Semin Oncol.

Hematopoiesis

Multiple Factors Contribute to Anemia

Multiple factors, both disease-related and treatment-related, can cause anemia during HIV infection. HIV plasma viral load appears to correlate inversely with all hematologic values, suggesting a causative role of HIV in hematologic disorders. The disease can cause anemia by influencing cytokine production and suppressing hematopoiesis; decreasing erythropoietin concentrations; and increasing the risk of opportunistic infection with agents, such as Mycobacterium avium complex and parvovirus B-19.