RBC Disorders - Normocytic Anemia

Question 1

Normocytic, normochromic anemia

Answer 1

Nonhemolytic (underproduction) or hemolytic (destruction)

Hemolytic further classified as hemolysis that is intrinsic or extrinsic to the RBCs and intravascular or extravascular

Question 2

Intravascular hemolysis

Answer 2

Destruction of RBCs within vessels

v haptoglobin (binds Hb and carries it in blood to spleen to be reprocessed - attempt to save the Hb)

Schistocytes and ^ reticulocytes on blood smear
Hemoglobinemia, hemoglobinuria, hemosiderinuria, urobilinogen in urine
^ unconjugated bilirubin (maybe)
^LDH

Notable causes: mechanical hemolysis (e.g. prosthetic valves), paroxysmal nocturnal hemoglobinuria, microangiopathic hemolytic anemias

Question 3

Extravascular hemolysis

Answer 3

RBC destruction by reticuloendothelial system (macrophages of spleen, liver, and lymph nodes)
Macrophages consume RBCs and break down Hb
Macrophages in spleen clear RBCs

sphereocytes in peripheral smear
^ LDH, ^ UCB (can –> jaundice), splenomegaly
no hemoglobinuria/hemosiderinuria
can present w urobilinogen in urine
marrow hyperplasia w corrected reticulocyte count >3%

Question 4

Nonhemolytic, normocytic anemia

Answer 4

Decreased production of RBCs by bone marrow
Low corrected reticulocyte count

Etiologies: causes of micro and macrocytic anemia, renal failure, damage to bone marrow precursor cells

Includes ACD (early), Parovirus B19, Aplastic Anemia, Myelophthisic processes

Question 5

Anemia of chronic disease

Answer 5

Normocytic, but can become microcytic

Inflammation –> ^ hepcidin (released by liver, binds ferroportin on intestinal mucosal cells and macrophages, thus inhibiting iron transport) –> v release of iron from macrophages and v iron absorption from gut

v iron, v TIBC, ^ ferritin

Assoc w rheumatoid arthritis, SLE, neoplastic disorders, chronic kidney disease

Tx: EPO (chronic kidney disease only)

Question 6

Aplastic Anemia

Answer 6

Caused by failure or destruction of myeloid stem cells due to:

• radiation and drugs (benzene, chloramphenicol, alkylating agents, antimetabolites)
• viral agents (parvovirus B19, HIV, EBV, hepatitis)
• Fanconi anemia (DNA repair defect –> bone marrow failure; short stature, ^ tumors/leukemia, cafe-au-lait spots, thumb/radial defects)
• idiopathic

v reticulocyte count, ^ EPO

Pancytopenia w severe anemia, leukopenia, thrombocytopenia
Normal cell morphology
Hypocellular bone marrow w fatty infiltrate (dry bone marrow tap)

Symptoms: fatigue, malaise, pallor, purpura, mucosal bleeding, petechiae, infection

Tx: withdraw offending agent, immunosuppressive regimens, bone marrow allograft, RBC/platelet transfusion, bone marrow stimulation

Question 7

Parovirus B19

Answer 7

Infects progenitor red cells and temporarily halts erythropoiesis
–> significant anemia in setting of preexisting bone marrow stress
Tx: supportive - usu self-limited infection

Question 8

Myelophthisic Process

Answer 8

Pathologic process (e.g. metastatic cancer) that replaces bone marrow 
Hematopoiesis is impaired --> pancytopenia