Normocytic Anemia

Normocytic anemia is a type of anemia and is a common issue that occurs for people typically over 85 years old. Its prevalence increases with age, reaching 44 percent in men older than 85 years. The most common type of normocytic anemia is anemia of chronic disease. The mean corpuscular (or cell) volume (MCV) is the index most often used because it reflects the average volume of each red blood cell. It is calculated as follows:

$MCV={Hematocrit \over RBC(cells/l)}$

Cells with a low MCV are microcytic, and the ones with a high MCV are macrocytic. These size categories are used to classify anemias. MCV is less useful when mixed cell populations are present.

Pathophsyiology

If blood loss exceeds 20% of blood volume, the immediate threat is hypovolemic shock rather than anemia. If the patient survives, hemodilution begins at once and achieves its full effect within 2 to 3 days; only then is the full extent of the red cell loss revealed. The anemia is normocytic and normochromic. Recovery from blood loss anemia is enhanced by a compensatory rise in the erythropoietin level, which stimulates increased red cell production and reticulocytosis within a period of 5 to 7 days:

• Increased peripheral loss → high reticulocytes w/ hypercellular BM Acute blood loss

• Hemolytic anemia (peripheral RBC destruction):

• Extravascular: Sickle cell anemia, Spherocytosis → inc. serum unconj. Bilirubin & jaundice & pigment stones

• Intravascular: Paraoxysmal nocturnal hemoglobinuria, G6PD, Immune Hemolytic Anemia, Malaria → inc. serum Hb → Hemoglobinuria + low haptoglobin

• Underproduction → low reticulocytes Decreased Erythropoiesis:
• Aplastic anemia: Hypocellular BM with Pancytopenia → ↓ RBCs, Platelets, WBCs
• Endocrinopathies: ↓ EPO (chronic kidney disease)
• Early stages of Iron def. (sideropenic) anemia + Chronic disease (ACD) → later microcytic

Reticulocyte % is falsely elevated in anemia: Less of RBCs + same Reticulocytes = higher reticulocyte % without extra reticulocyte production. If we multiply the reticulocyte percentage by the % of hematocrit → gives real reticulocyte count elevation. If reticulocyte count is not elevated with anemia then there is a problem with bone marrow function. If due to increased peripheral loss → anemia with reticulocyte % elevation over 3% If due to underproduction → anemia with no reticulocyte % elevation less than 3%.

Etiology

Most normochromic, normocytic anemias are a consequence of other diseases; a minority reflects a primary disorder of the blood. This may be due to anemia of chronic disease (inflammation, neoplasia), renal failure, endocrine failure (hypothyroidism, hypopituitarism), marrow failure (pure red-cell aplasia, aplastic anemia, infiltration), acute blood loss, and polymyalgia rheumatica.[6] The etiology of normocytic normochromic anemia depends on whether the anemia is hypoproliferative (ie, corrected reticulocyte count <2%) or hyperproliferative (ie, corrected reticulocyte count >2%).[7][8]

Normal/Decreased Reticulocyte Count

• Normal bone marrow
  • Anemia of chronic disorders (neoplastic, infections)
  • Anemia of renal failure
  • Endocrinopathy (myxedema, Addison's disease, hypothyroidism, panhypopituitarism)
  • Anemia of liver disease
  • Early iron-deficiency anemia

• Abnormal bone marrow
  • Marrow infiltration (leukemia, myelofibrosis, metastasis)
  • Hypoplastic anemia
  • Aplastic anemia
  • Medication side effect

Increased Reticulocyte Count

• Hemolysis
  • Intrinsic: Inherited defects of hemoglobin, RBC membrane, or enzyme; paroxysmal nocturnal hemoglobinuria
  • Extrinsic: Autoimmune hemolytic anemia, microangiopathic hemolytic anemia, disseminated intravascular coagulation

• Hemorrhage
  • Given normal iron stores, reticulocyte count should be increased to above 2.5%

Treatment

Normocytic anemia treatment focuses on the underlying condition. For example, if you have aplastic anemia, your treatment may include antibiotics, blood transfusions and immunosuppressants. A condition that makes your red blood cells break down, like DIC. You may receive anticoagulant medication or plasma transfusions.