Anemia Dr. Meg-angela Christi M. Amores
What is Hematopoeisis? • It is the process by which the formed elements of the blood are produced • Erythropoeisis: production of erythrocytes (red blood cells) • Regulatory hormone: EPO (erythropoeitin) • kidney
Erythropoeisis • Critical elements: • EPO production • iron availability • the proliferative capacity of the bone marrow • effective maturation of red cell precursors
Anemia • Often recognized by abnormal screening tests • Less commonly presents signs and symptoms unless advanced • Acute anemia – due to blood loss or hemolysis • If acute blood loss, hypovolemia results • Hypotension is the issue, not anemia • 10 – 15% blood loss- signs of vascular instability • >30% - postural hypotension, tachycardia • >40% - hypovolemic shock (confusion, dyspnea, diaphoresis, hypotension, tachycardia)
Anemia • Acute anemia – due to blood loss or hemolysis • Acute hemolysis • Symptoms: fatigue, loss of stamina, breathlessness, and tachycardia (particularly with physical exertion) • Most often only occurs when advanced (hgb <7 mg/dL)
Approach to patient • History: • Nutritional (food, drugs, alcohol) • Family history • G6PD deficiency • PE: • Findings of infection • blood in the stool, lymphadenopathy, splenomegaly, or petechiae • forceful heartbeat, strong peripheral pulses, and a systolic "flow" murmur
Pallor • skin and mucous membranes may be pale if the hemoglobin is <80–100 g/L (8–10 g/dL) • If palmar creases are lighter in color than the surrounding skin when the hand is hyperextended, the hemoglobin level is usually <80 g/L (8 g/dL)
Laboratory Evaluation
Normal Hgb and Hct levels
CBC • Components of CBC help in the classification of anemia: • Microcytosis - reflected by a lower than normal MCV (<80) • Macrocytosis - high values (>100) of MCV • MCH and MCHC reflect defects in hemoglobin synthesis - hypochromia
Peripheral blood smear • provides important information about defects in red cell production • the blood smear also reveals variations in cell size (anisocytosis) and shape (poikilocytosis)
Reticulocyte count • key to the initial classification of anemia • Normally, the reticulocyte count ranges from 1–2% and reflects the daily replacement of 0.8–1.0% of the circulating red cell population • reticulocyte count provides a reliable measure of red cell production • In the face of established anemia, a reticulocyte response less than two to three times normal indicates an inadequate marrow response.
Tests of Iron Supply and storage • serum iron • TIBC • percent transferrin saturation • serum ferritin is used to evaluate total-body iron stores
Bone Marrow examination • Indications: • patients with hypoproliferativeanemia and normal iron status • can diagnose primary marrow disorders such as myelofibrosis, a red cell maturation defect, or an infiltrative disease
Functional Classification • marrow production defects (hypoproliferation) • red cell maturation defects (ineffective erythropoiesis) • decreased red cell survival (blood loss /hemolysis)
HypoproliferativeAnemia • 75% of all anemia • reflects absolute or relative marrow failure • Majority are due to mild to moderate iron deficiency or inflammation • can result from marrow damage, iron deficiency, or inadequate EPO stimulation • normocytic, normochromic red cells • Key diagnostic tool: IRON studies
HypoproliferativeAnemia • anemia of acute or chronic inflammation • serum iron (low), TIBC (normal or low), percent transferrin saturation (low), and serum ferritin (normal or high) • mild to moderate iron deficiency • (low serum iron, high TIBC, low percent transferrin saturation, low serum ferritin)
Maturation disorders • anemia with an inappropriately low reticulocyte production index, macro- or microcytosis on smear, and abnormal red cell indices • ineffective erythropoiesis that results from the destruction within the marrow • vitamin B12 or folic acid deficiency, drug damage, or myelodysplasia
Blood Loss / HemolyticAnemia • Red blood cell indices >2.5x the normal • stimulated erythropoiesis • typically normocytic or slightly macrocytic • Hemolysis – least common form of anemia • present in different ways • paroxysmal nocturnal hemoglobinuria • Hemoglobinopathies • hereditary spherocytosis
Treatment • Severe anemia: red cell transfusions • acute or gradual onset: determined by the documented cause(s) of the anemia • important to evaluate the patient's iron status fully • Chronic kidney disease: Recombinant EPO
