Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1189 page)

   Interpretation

   The RBC count is interpreted in conjunction with red cell indices, hemoglobin, and hematocrit.

Increased In

   Certain myeloproliferative neoplasms (e.g., polycythemia vera).

   Severe dehydration. RBC counts may be
appropriately
decreased or increased in certain physiologic states.

Decreased In

   Various types of anemia

Abnormal RBC Morphology

   It is flagged by automated counters, triggering microscopic examination of stained peripheral blood smears (see above).

   Abnormalities (see Tables 16.72 and 16.73) may be specific for certain conditions (e.g., spherocytes for hemolytic anemias, sickle cells for sickle cell anemias) or may be informative but not specific.
Anisocytosis
refers to variation in RBC size,
poikilocytosis
refers to variation in shape, and
polychromasia
refers to bluish discoloration of RBC reflecting high reticulocytes.

TABLE 16–72. Abnormal Shapes of Red Blood Cells

TABLE 16–73. Red Blood Cell Inclusions

   Limitations

   Patient’s circumstances (e.g., vomiting or diarrhea)

   Other preanalytic factors