Hematology

1 Define anemia.

Hemoglobin less than 12 mg/dL in women or less than 14 mg/dL in men.

2 What are the symptoms and signs of anemia?

Symptoms: Fatigue, dyspnea on exertion, light-headedness, dizziness, syncope, palpitations, angina, and claudication.

Signs: Tachycardia, pallor (especially of the sclera and mucous membranes), systolic ejection murmurs (from high flow), and signs of the underlying cause (e.g., jaundice, pigment gallstones (Fig. 17-1; Plate 29) in hemolytic anemia, positive stool guaiac with a gastrointestinal [GI] bleed).

Figure 17-1 Pigment gallstones within an otherwise unremarkable gallbladder are a marker for hemolytic anemia. See Plate 29. (From Kumar V, Abbas AK, Fausto N, Aster JC. Robbins and Kotran pathologic basis of disease, professional edition. 8th ed. Philadelphia: Saunders, 2009, Fig. 18-53.)

3 What are the important elements of the history when anemia is present?

Important points include medications, blood loss (e.g., trauma, surgery, melena, hematemesis, menorrhagia), chronic diseases (anemia of chronic disease), family history (e.g., hemophilia, thalassemia, sickle cell disease, glucose-6-phosphatase deficiency), and alcoholism (which may lead to iron, folate, and B₁₂ deficiencies as well as GI bleeds).

4 What medications can cause anemia? How?

Many medications can cause anemia through various mechanisms. Methyldopa, penicillins, and sulfa drugs can cause red blood cell (RBC) antibodies with subsequent hemolysis; chloroquine and sulfa drugs cause hemolysis in patients with glucose-6-phosphatase deficiency; phenytoin causes megaloblastic anemia through interference with folate metabolism; and chloramphenicol, cancer drugs, and zidovudine cause aplastic anemia and bone marrow suppression. Other drugs also are implicated, but this list should be sufficient for answering questions on the USMLE.

5 What test should be ordered first to help determine the cause of anemia?

The complete blood count (CBC) with red blood cell indices. First and foremost, the hemoglobin must be below normal to diagnose anemia. The mean corpuscular volume (MCV) tells you whether the anemia is microcytic (MCV < 80), normocytic (MCV = 80-100), or macrocytic (MCV > 100).

6 What test should be ordered next?

Peripheral blood smear. There are many “classic” findings that can help make the diagnoses:

Sickled cells (sickle cell disease; Fig. 17-2; Plate 30).

Figure 17-2 Sickle cells show a sickle or crescent shape resulting from the polymerization of hemoglobin S. This smear also shows target cells and boat-shaped cells with a lesser degree of polymerization of hemoglobin S than in a classic sickle cell. See Plate 30. (From Goldman L, Schafer AI. Goldman’s Cecil medicine. 24th ed. Philadelphia: Saunders, 2011, Fig. 160-7.)

Hypersegmented neutrophils (folate/B₁₂ deficiency; Fig. 17-3; Plate 31).

Figure 17-3 Megaloblastic changes of macrocytosis and a hypersegmented neutrophil. See Plate 31. (From Rakel RE, Rakel DP. Textbook of family medicine. 8th ed. Philadelphia: Saunders, 2011, Fig. 39-4; The American Society of Hematology Image Bank image #2611. Copyright 1996 American Society of Hematology, used with permission.)

Hypochromic and microcytic RBCs (iron deficiency; Fig. 17-4; Plate 32).

Figure 17-4 Iron-deficiency anemia. Pale red blood cells (RBCs) with enlarged central pallor. See Plate 32. (From McPherson R, Pincus M. Henry’s clinical diagnosis and management by laboratory methods. 21st ed. Philadelphia: Saunders, 2006, Fig. 31-2.)

Basophilic stippling (lead poisoning; Fig. 17-5; Plate 33).

Figure 17-5 Basophilic stippling. Irregular basophilic granules in red blood cells (RBCs); often associated with lead poisoning and thalassemia. See Plate 33. (From McPherson R, Pincus M. Henry’s clinical diagnosis and management by laboratory methods. 21st ed. Philadelphia: Saunders, 2006, Fig. 29-23.)

Heinz bodies (glucose-6-phosphatase deficiency; Fig. 17-6; Plate 34).

Figure 17-6 Bite cells with Heinz bodies. See Plate 34. (Courtesy Dr. Robert W. McKenna, Department of Pathology, University of Texas Southwestern Medical School, Dallas, Texas.)

“Bite cells” (classically, glucose-6-phosphatase deficiency; other hemolytic anemias; Fig. 17-6; Plate 34).

Howell-Jolly bodies (asplenia; Fig. 17-7; Plate 35).

Figure 17-7 Howell-Jolly bodies in peripheral blood erythrocytes. These nuclear remnants indicate lack of splenic filtrative function. See Plate 35. (From Orkin SH, et al. Nathan and Oski’s hematology of infancy and childhood. 7th ed. Philadelphia: Saunders: 2009, Fig. 14-4.)

Teardrop-shaped RBCs (myelofibrosis; Fig. 17-8; Plate 36).

Figure 17-8 Teardrop red blood cells (RBCs), usually seen in myelofibrosis. See Plate 36. (From Goldman L, Ausiello D. Cecil medicine. 23rd ed. Philadelphia: Saunders, 2008, Fig. 161-13.)

Schistocytes, helmet cells, and fragmented RBCs (intravascular hemolysis; Fig. 17-9; Plate 37).

Figure 17-9 Schistocytes and helmet cells. Red blood cell (RBC) fragments seen with microangiopathic hemolytic anemia and disseminated intravascular coagulation (DIC). See Plate 37. (From McPherson R, Pincus M. Henry’s clinical diagnosis and management by laboratory methods. 21st ed. Philadelphia: Saunders, 2006, Fig. 29-19.)

Spherocytes and elliptocytes (hereditary spherocytosis and elliptocytosis; Fig. 17-10; Plate 38).

Figure 17-10 Hereditary elliptocytosis. Blood film reveals characteristic elliptical red blood cells (RBCs). See Plate 38. (From McPherson RA, Pincus MR. Henry’s clinical diagnosis and management by laboratory methods. 22nd ed. Philadelphia: Saunders, 2011, Fig. 30-16.)

Acanthocytes and spur cells (abetalipoproteinemia; Fig. 17-11; Plate 39).

Figure 17-11 Acanthocytes. Irregularly spiculated red blood cells (RBCs), frequently seen in abetalipoproteinemia or liver disease. See Plate 39. (From McPherson R, Pincus M. Henry’s clinical diagnosis and management by laboratory methods. 21st ed. Philadelphia: Saunders, 2006, Fig. 29-20.)

Target cells (thalassemia, liver disease; Fig. 17-12; Plate 40).

Figure 17-12 Target cells are frequently seen in hemoglobin C disease and liver disease. See Plate 40. (From McPherson R, Pincus M. Henry’s clinical diagnosis and management by laboratory methods. 21st ed. Philadelphia: Saunders, 2006, Fig. 29-18.)

Echinocytes, including “burr” cells and acanthocytes (uremia; Fig. 17-13; Plate 41).

Figure 17-13 Echinocytes, or burr cells *(arrows),* are the hallmark of uremia. See Plate 41. (Hoffman R, et al. Hematology: basic principles and practice. 5th ed. Philadelphia: Churchill Livingstone, 2008, Fig. 156-1.)

Polychromasia (from reticulocytosis; should alert you to the possibility of hemolysis; Fig. 17-14; Plate 42).

Figure 17-14 Microangiopathic hemolytic anemia demonstrating red blood cell (RBC) fragments, anisocytosis, polychromasia, and decreased platelets. See Plate 42. (From Tschudy MM, Arcara KM, editors. The Harriet Lane handbook. 19th ed. Philadelphia: Mosby, 2011, Plate 7.)

Rouleaux formation (multiple myeloma; Fig. 17-15; Plate 43).

Figure 17-15 Rouleaux formation of stacked red blood cells (RBCs) seen in multiple myeloma. See Plate 43. (From Goldman L, Ausiello D. Cecil Medicine. 23rd ed. Philadelphia: Saunders, 2008, Fig. 161-19.)

Parasites inside red blood cells (RBCs) (malaria [Fig. 17-16; Plate 44], babesiosis).

Figure 17-16 Malaria. Peripheral blood film examples of various stages of *Plasmodium falciparum.* A, Small ring forms. B, A crescentic gametocyte with centrally placed chromatin. See Plate 44. (From Hoffman R, et al. Hematology: basic principles and practice. 5th ed. Philadelphia: Churchill Livingstone, 2008, Fig. 159-5.)

Iron inclusions in RBCs of the bone marrow (sideroblastic anemia; Fig. 17-17; Plate 45).

Figure 17-17 Ringed sideroblasts seen in sideroblastic anemia. See Plate 45. (From Goldman L, Ausiello D. Cecil medicine. 23rd ed. Philadelphia: Saunders, 2008, Fig. 163-5.)

7 What are reticulocytes? Why is a reticulocyte count routinely ordered in an anemia workup?

Reticulocytes are immature RBCs. If their count is abnormally decreased in the setting of anemia, the marrow is not responding properly and is the problem. A high reticulocyte count should make you think of hemolysis or blood loss as the cause (the marrow is responding properly and is not the problem).

8 Which test comes next?

At this point, it depends. If you have a complete history and results of the other three tests (CBC with red blood cell indices, peripheral smear, and reticulocyte count), most possibilities will be eliminated and you can order a confirmatory test. If the answer is still not clear, consider a bone marrow biopsy. For the Step 2 examination, biopsy is unlikely to be necessary unless malignancy is the cause of the anemia.

9 What are the classic causes of microcytic, normocytic, and macrocytic anemia? Which of these tends to have an inappropriately low reticulocyte count?

MICROCYTIC	NORMOCYTIC
With normal or elevated reticulocyte count	With normal or elevated reticulocyte count
Thalassemia/hemoglobinopathy (e.g., sickle cell disease)	Acute blood loss Hemolytic (multiple causes) Medications (antibody-causing)
With low reticulocyte count	With low reticulocyte count
Lead poisoning Sideroblastic anemia Anemia of chronic disease (some cases) Iron deficiency	Cancer/dysplasia (e.g., myelophthisic anemia, acute leukemia) Anemia of chronic disease (some cases) Aplastic anemia/medications causing bone marrow suppression Endocrine failure (thyroid, pituitary) Renal failure
MACROCYTIC
All types have low reticulocyte count
Folate deficiency Vitamin B₁₂ deficiency Medications (methotrexate, phenytoin) Alcohol abuse (interferes with folate use) Cirrhosis, liver disease

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Apr 8, 2017 | Posted by admin in NURSING | Comments Off

1 Define anemia.

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Hematology

Hematology

2 What are the symptoms and signs of anemia?

3 What are the important elements of the history when anemia is present?

4 What medications can cause anemia? How?

5 What test should be ordered first to help determine the cause of anemia?

6 What test should be ordered next?

7 What are reticulocytes? Why is a reticulocyte count routinely ordered in an anemia workup?

8 Which test comes next?

9 What are the classic causes of microcytic, normocytic, and macrocytic anemia? Which of these tends to have an inappropriately low reticulocyte count?

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