Anaemia Flashcards
What is anaemia?
Anemia is strictly defined as a decrease in red blood cell (RBC) mass.
Causes of reduced RBC mass
The decrease may result from blood loss, increased destruction of RBCs (hemolysis), or decreased production of RBCs.
Work up: measuring RBC mass
Methods for measuring RBC mass are time consuming and expensive and usually require transfusion of radiolabeled erythrocytes.
Thus, in practice, anemia is usually discovered and quantified by measurement of the RBC count, Hb concentration, and hematocrit (Hct).
These values should be interpreted cautiously, because they are concentrations affected by changes in plasma volume.
For example, dehydration elevates these values, and increased plasma volume in pregnancy can diminish them without affecting the RBC mass.
Complications of Anaemia
The most serious complications of severe anemia arise from tissue hypoxia. Shock, hypotension, or coronary and pulmonary insufficiency can occur. This is more common in older individuals with underlying pulmonary and cardiovascular disease.
