Laboratory Tests and Interpretation

Hemoglobin:

• Normal hemoglobin ranges are approximately:

  • 14-18.5 g/dL for males

  • 12-16.5 g/dL for females

Mean Corpuscular Volume (MCV):

• MCV <80 fL

  • Microcytic anemia

• MCV 80-100 fL

  • Normocytic anemia

• MCV >100 fL

  • Macrocytic anemia

(Refer to Anemia lecture for advanced information)

Red cell distribution width (RDW):

• Measures variation in red blood cell size

• Diagnostic value in differentiating types of anemia

Mentzer index:

• Calculated as MCV divided by RBC count

• Differentiate iron def. anemia from beta-thalassemia trait in microcytic anemia.

  • Mentzer index >13 suggests iron deficiency anemia

  • Mentzer index < 13 suggests beta-thalassemia trait

• Should be used as a screening tool rather than a definitive diagnostic test.

Reticulocyte production index (RPI):

• Retic % × (Patient's Hct / Normal Hct)

  • RPI >2-3 :

    • Appropriate BM response to anemia (hemolysis, acute blood loss)

  • RPI ≤2 :

    • Inadequate erythropoiesis (iron deficiency, BM suppression, chronic disease)

Leukocytosis:

Causes (beside malignancies)

• Elevated monocytes:

  • Chronic infections

  • Rheumatologic conditions

• Elevated eosinophils:

  • Parasitic infections

  • Allergic reactions

  • Connective tissue disorders

• Elevated neutrophils:

  • Infection

  • Inflammation

  • Stress response

  • Splenic sequestration

  • Asplenia

• Elevated lymphocytes:

  • Viral infection (EBV, CMV, etc)

  • Pertussis

  • Tuberculosis

  • Splenic sequestration

  • Asplenia

• Elevated basophils:

  • Viral infections

  • Inflammatory conditions

Peripheral Blood Smear (PBS):

• Marked increase of normal appearing lymphocytes:

  • Possible CLL

• Blast cells + predominant basophilia and eosinophilia:

  • Possible CML

• >20% blasts in blood or BM:

  • Acute leukemia:

    • >20% lymphoblasts

      • Possible ALL

    • >20% myeloblasts

      • Possible AML

• Atypical lymphocytes:

  • EBV, CMV, HIV

IN PROGRESS...