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Test ID: HSEP    
Hereditary Spherocytosis Evaluation

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Useful For Suggests clinical disorders or settings where the test may be helpful

Investigation of suspected hereditary spherocytic hemolytic anemia

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

The hemolytic anemias are a group of anemias that are characterized by an increased destruction of RBCs. Anemias may be divided into inherited or acquired. Hereditary spherocytosis (HS), also known as congenital hemolytic anemia, is inherited as a non-sex-linked dominant trait. HS is caused by a RBC membrane defect. The RBCs are spherocytic in shape and show an increased rate of destruction. HS can result from abnormalities involving several red cell membrane proteins, such as band 3, spectrin, and ankyrin.

 

Most often HS is diagnosed in childhood, adolescence, or early adult life. The diagnosis of HS is usually made by a combination of patient and family history, laboratory evidence of hemolysis, and review of a peripheral blood smear. The osmotic fragility test is usually markedly abnormal in these cases. However, factors such as age, sex, and medications can affect the osmotic fragility test.

 

This evaluation combines osmotic fragility testing with a newly developed flow cytometry assay to provide complementary information in the evaluation of patients with suspected HS.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

> or equal to 12 months:

0.50 g/dL NaCl (unincubated)

Males: 0.0-47.8% hemolysis

Females: 0.0-31.1% hemolysis

 

0.60 g/dL NaCl (incubated)

Males: 18.7-67.4% hemolysis

Females: 10.9-65.5% hemolysis

 

0.65 g/dL NaCl (incubated)

Males: 4.4-36.6% hemolysis

Females: 0.2-39.3% hemolysis

 

0.75 g/dL NaCl (incubated)

Males: 0.8-9.1% hemolysis

Females: 0.0-10.9% hemolysis

 

An interpretive report will be provided.

 

Reference values have not been established for patients who are <12 months of age.

Interpretation Provides information to assist in interpretation of the test results

An interpretive report will be provided.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Interfering factors:

-Recent transfusion

-Oral contraceptives

-H2 blockers      

Infrequently, other hemolytic disorders may also be associated with positive results, as in patients with congenital nonspherocytic hemolytic anemia due to glucose-6-phosphate dehydrogenase or pyruvate kinase deficiency.

 

Patients with an immunohemolytic anemia, or who have recently received a blood transfusion may also have increased RBC lysis.

 

The shipping control specimen is required to adequately interpret these cases, as temperature extremes can increase fragility of the specimen. 

 

Resulting Cautions:

Osmotic fragility results will be reported if the shipping control is normal.

 

If the shipping control is abnormal and the osmotic fragility results are within normal range, the results will be reported; however, a comment will be added to the report indicating that the shipping control was not entirely satisfactory.

 

The test will be cancelled if the patient specimen and shipping control are both abnormal. 

Clinical Reference Provides recommendations for further in-depth reading of a clinical nature

1. Gladen BE, Luicens JN: Hereditary spherocytosis and other anemias due to abnormalities of the red cell membrane. In Wintrobe's Clinical Hematology. 10th edition. Edited by GR Lee, J Foerester, J Lukens, et al. Baltimore, Williams and Wilkins, 1999, pp 1132-1159

2. Gallagher PG, Jarolim P: Red cell membrane disorders. In Hematology: Basic Principles and Practice. Third edition. Edited by R Hoffman, EJ Benz, SJ Shattil, et al: New York, Churchill Livingstone, 2000, pp 576-610

Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test