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Test Code HS SCREEN Hereditary Spherocytosis Screen

Clinical System Name

Hereditary Spherocytosis Screen

Synonyms

Fragility, RBC
osmotic fragility
Red Cell Fragility

Description

This test is a flow cytometric analysis of the red blood cells band 3 membrane protein stained with the dye, Eosin-5-maleimide.  The assay is used in the evaluation for Hereditary Spherocytosis.  Note: The osmotic fragility test is no longer available.

Sample Requirements

Specimen:  Whole Blood

Container(s):  Lavender/EDTA

Preferred Vol:  3 mL

Minimum Vol:  0.5 mL or 1 lavender microtainer

 

Note: 

Specimen can be collected 24 hours a day, 7 days a week. Both venipuncture and capillary collections are acceptable. Test may be added to CBC specimen in lab. Pre-transfusion specimen is preferred. No patient age restriction for testing.

Processing Instructions

Reject due to:  n/a - send to lab

Spin: N

Aliquot:  N

Temp:  RT

Storage location:  Days:  Transport specimen, community services requisition, if applicable, and labels to 10th floor Cell Markers (station #280).    Eves/Nights/Off Hours:  Store specimen, requisition (if applicable) and labels in the Cell Markers box in CPA refrigerator #1.

 

Off-site collection:  Sent in specimens drawn from outside locations are acceptable.  Refrigerate whole blood and transport to Seattle Childrens as soon as possible.  Please send a copy of the patient's most recent CBC and differential results with the specimen.  Note: room temp is acceptable, but refrigeration is recommended for longer specimen stability.

Stability

Temperature Time
Room temp 48 hours
Refrigerated

96 hours

Frozen N

 

Availability

STAT Performed TAT
Y - with pathologist approval collected daily; performed M-Sat 2-3 days

 

Performing Laboratory

Seattle Children's Laboratory  

Department

Department:   Cell Markers

Phone Number: 206-987-2560

 

Reference Range

 

Negative

 

Methodology

Method:  Flow Cytometry

Analytical Volume:  0.1 mL

 

Limitations:  Specimens from newborns are acceptable for testing by this method

 

KNOWN FALSE POSITIVES:

Southeast Asian ovalocytosis

 

Congenital dyserythropoietic anemia type II

 

Cryohydrocytosis

KNOWN FALSE NEGATIVES:

normal EMA-binding in single ankyrin-deficiency HS

OTHER CAUSES OF INCREASED FLUORESCENCE (POSSIBLE FALSE NEGATIVE):   

BLOOD TRANSFUSIONS

According to reports in the literature, spherocytic red cells are detectable in the peripheral blood of a transfused HS patient, provided that a blood transfusion given does not exceed one-half of the total blood volume. In patients that have had a recent red blood cell transfusion a second peak with increased fluorescence may be detected or a single peak with an increased HPCV.

RETICULOCYTES

Retics have increased red cell membrane proteins that bind EMA. In patients with significantly elevated reticulocytes, a second peak with increased fluorescence may be detected or a single peak with an increased HPCV.

 

CPT Codes

CPT CODE(S)
88184