The reticulocyte count is the most effective means of assessing red cell generation or response to anemia. Reticulocytes are red cells that are nonnucleated and that contain remnant RNA material, reticulum. Reticu-lum cannot be visualized by Wright's stain; to be counted and evaluated, reticulocytes must be stained with supravital stains, like new methylene blue or brilliant cresyl blue. On Wright's stain, reticulocytes are seen as polychromatophilic macrocytes, or large, bluish cells. The normal reticulocyte rate is 0.5% to 1.5 % in the adult and 2.0% to 6.0% in the newborn. Because the bone marrow has the capacity to expand its production up to 7 times the normal rate, an elevated reticulocyte count or reticulocytosis is the appropriate response in anemic stress. Reticulocytes will be seen in the peripheral smear as polychromatophilic macrocytes; nucle-
Table 2.7 O Symptoms of Anemia Linked to Pathophysiology
• Decreased oxygen transport leads to fatigue, dyspnea, angina pectoris, and syncope
• Decreased blood volume leads to pallor, postural hypotension, and shock
• Increased cardiac output leads to palpitation, strong pulse, and heart murmurs ated red blood cells may also be visualized in the peripheral smear as the bone marrow races to deliver cells prematurely at a rapid rate. EPO production is increased in response to hypoxia (anemia), and ery-throid hyperplasia in the bone marrow (the condition in which there are more red cell precursors than white cell precursors being produced) is clear evidence of rapid generation. Failure to produce the expected reticulo-cyte increase may occur in ineffective erythropoiesis, a condition where red cell precursors are destroyed before they are delivered to the peripheral circulation, or if the bone marrow is infiltrated with tumor or abnormal cells, etc. A decreased reticulocyte count may also be seen in aplastic conditions, where the production of either white or red cells or both is seriously impaired. In any event, the level of reticulocyte response or lack of reticulocyte response is an important indicator of bone marrow function.
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