O

Microspherocyte

Figure 7.2 Three mechanisms of spherocyte formation.

100 Part II • Red Cell Disorders mune process are the result of an antibody being attached to the red cell and then removed or sheared as the coated red cell passes through the spleen. As this occurs, the exterior membrane of the red cell is sheared and a spherocyte produced. A more moderated spherocyte-producing process is senescence, or natural red cell death. As the cell ages, it progressively loses membrane, leading to the production of spherocytes. However, in the normal peripheral smear, spherocytes are not seen because they are removed by the spleen under normal circumstances of cell death.

Laboratory Diagnosis of Hereditary Spherocytosis

The laboratory diagnosis of HS is relatively easy in an individual with elevated MCHC, RDW, and the presence of spherocytes. Because most individuals have mild or moderate disease and share a common clinical laboratory picture, additional laboratory testing is usually not necessary. The confirmatory tests, though, are labor intensive and usually not offered as part of a regular laboratory menu of test items. The osmotic fragility test, incubated and unincubated, is the test of choice to confirm a diagnosis of HS. Red blood cells from patients suspected of having HS are subjected to varying salt solutions ranging from isotonic saline (0.85% NaCl) to distilled water (0.0% NaCl). Under isotonic conditions, normal red cells reach equilibrium and have little hemolysis. As the solutions become more hypotonic (less salt and more water), hemolysis occurs and is observed at the initial appearance of hemolysis and after complete hemolysis. The level of complete hemolysis is usually the only data reported on the patient sample. Normal red cells initially hemolyze at 0.45% NaCl. Red cells from patients with HS have a decreased surface to volume ratio and an increased osmotic fragility. They are less able to tolerate an influx of water and therefore lyse at 0.65% (Fig. 7.3). An increased osmotic fragility curve will be seen in conditions other than HS such as autoimmune hemolytic anemia or any of the acquired hemolytic processes. Conditions such as thalassemia and iron deficiency anemia will show a reduced osmotic fragility (hemolysis at 0.20%) owing to the high number of target cells, a red cell morphology with a capacity to intake a high influx of water before hemolysis.

Treatment and Management of Hereditary Spherocytosis

It should come as no surprise that because the spleen is the offending organ in HS, splenectomy is often suggested as a remedy for moderate to severe hemolysis in

Figure 7.3 Osmotic fragility curves. Normal patient's plot is shown in the shaded area. The curve to the right shows a decreased fragility as seen in patients with sickle cell anemia. The curve to the left shows an increased fragility as seen in patients with hereditary spherocytosis.

Figure 7.3 Osmotic fragility curves. Normal patient's plot is shown in the shaded area. The curve to the right shows a decreased fragility as seen in patients with sickle cell anemia. The curve to the left shows an increased fragility as seen in patients with hereditary spherocytosis.

this disease. Removal of the spleen will diminish the anemia by allowing the spherocytes to remain in the circulation longer, thus reducing the need for blood transfusion, and in some cases minimizing gallbladder disease. Splenectomy is a procedure that demands serious consideration before approval. Splenectomy in younger children poses serious risks to those children by making them more vulnerable to infections with encapsulated organisms. Prophylactic penicillin should be offered postsurgery to this age group, or a partial splenectomy surgical procedure should be considered. Partial splenectomy is known to reduce hemolysis while preserving important immune splenic function.9 If symptoms return as a result of remaining splenic tissue, a total splenectomy may be considered once the patient has the appropriate management and support.

The Prevention and Treatment of Headaches

The Prevention and Treatment of Headaches

Are Constant Headaches Making Your Life Stressful? Discover Proven Methods For Eliminating Even The Most Powerful Of Headaches, It’s Easier Than You Think… Stop Chronic Migraine Pain and Tension Headaches From Destroying Your Life… Proven steps anyone can take to overcome even the worst chronic head pain…

Get My Free Audio Book


Post a comment