Cardiovascular system: Anemia and clinical case

Anemia is a condition in which the number of red blood cells or the level of blood hemoglobin is reduced from an individual's baseline. The clinical findings in an anemic patient are associated with decreased or insufficient oxygen delivery to the tissues, known as hypoxia. Because the causes of anemia are diverse, clinicians use multiple laboratory tests to evaluate the underlying etiology:

A patient’s hematocrit describes the proportion of whole blood that is made up of red blood cells. This can help identify whether a case of anemia is caused by a decrease in the number of red blood cells or a decrease in functional hemoglobin levels. Both hematocrit and hemoglobin concentration are volume dependent and therefore can be artificially increased or decreased depending on the patient’s volume status.

The reticulocyte count is a measure of the concentration of immature RBC precursors in circulation. If anemia is due to the decreased production of red blood cells – rather than the increased destruction or loss of red blood cells – the reticulocyte count will be below the normal range.

The mean corpuscular volume (MCV) describes the average volume of circulating RBCs. Anemia with a low MCV, referred to as microcytic anemia, usually results from decreased hemoglobin levels. Anemia with a normal MCV, or normocytic anemia, may be due to a condition known as aplastic anemia, in which the stem cell precursors to all blood components (RBCs, leukocytes, and platelets) are damaged. This results in a global decrease in the number of these cells, even though they appear normal.

A patient in the ER has dry, cracked lips and symptoms of severe anemia. His blood test results are shown in Table 1.

Table 1 Patient data

In what context might an anemic patient’s hematocrit and hemoglobin concentration both appear to be normal or elevated?

MCAT

Course: MCAT > Unit 2

Problem