Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (287 page)

   Young child who fails to thrive and is not as active as expected for age.

   Anemia detected at ages 3−6 months suggests a congenital disorder of Hb synthesis or structure.

   Adults.

   Nonspecific symptoms and signs such as weakness, dizziness, progressive lack of energy, pallor, and shortness of breath in the absence of serious heart or lung disease (overt CHF may develop as a consequence of severe anemia).

   Protracted GI or vaginal bleeding.

   A family history of anemia.

   Jaundice or red urine.

   Laboratory Findings

   Initial laboratory investigation should include a complete CBC with a reticulocyte count and examination of the peripheral blood smear (PBS). The reticulocyte count reflects bone marrow response to anemia.

   Once the suspicion of anemia is confirmed by finding a reduction in Hb (the RBC count may be normal or even higher in certain conditions, such a thalassemia trait), the type of anemia must be determined by subsequent laboratory investigations, based mostly on the MCV, and subdivided by pathophysiology.

   The RDW provides a useful measurement of the variation in size of RBCs, indicating the presence of anisocytosis when elevated.

   Once anemia is documented, subsequent investigations depend on the type of anemia suspected based on indices and the reticulocyte count (see Figure
9-1
). More complex laboratory tests or bone marrow biopsy may be indicated to ascertain its precise etiology.

   Various types of anemias are described subsequently.