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Lab Dept:
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Chemistry
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Test Name:
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HEXOSAMINIDASE A & TOTAL HEXOSAMINIDASE, SERUM
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General Information
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Lab Order Codes:
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HEXAT
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Synonyms:
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B-N-Acetylglucosaminidase; GM2 Gangliosidosis; Sandhoff Carrier Screening; Tay Sachs Carrier Screening
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CPT Codes:
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Enter code and description
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Test Includes:
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Total Hexosaminidase level reported as U/L, Hexoaminidase A reported as a % of total.
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Logistics
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Test Indications:
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Diagnosing Tay-Sachs disease, carriers of Tay-Sachs, Sandhoff’s disease, and carriers of Sandhoff’s disease.
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Lab Testing Sections:
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Chemistry - Sendouts
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Referred to:
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Mayo Medical Laboratories (MML Test#: 8774)
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Phone Numbers:
Minneapolis:
Saint Paul:
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612-813-6280
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651-220-6550
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Test Availability:
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Daily, 24 hours
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Turnaround Time:
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2 – 5 days
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Special Instructions:
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For females of child-bearing age: If females wish screening for carrier status of hexoaminidase A deficiency, they must be tested prior to pregnancy. Serum assay results are often ambiguous on pregnant females and will not be run.
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Specimen
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Specimen Type:
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Blood
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Container:
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Red top tube
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Draw Volume:
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3 mL (Minimum: 1.5 mL) blood
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Processed Volume:
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1 mL (Minimum: 0.5 mL) serum
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Collection:
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Routine venipuncture
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Special Processing:
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Lab Staff: Centrifuge specimen. Remove serum aliquot and place into a screw-capped plastic vial. Ship and store at frozen temperatures.
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Patient Preparation:
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None
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Sample Rejection:
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Warm specimens, samples from pregnant females, mislabeled or unlabeled specimens
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Interpretive
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Reference Range:
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Hexosaminidase A and Total, Serum (U/L)
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Age not given
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Reference values have not been established for patients that are less than 5 years of age.
10.4 - 23.8 U/L (>= 5 years)
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<5 years
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Reference values have not been established for patients that are less than 5 years of age.
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> or = 5 years:
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10.4 – 23.8 U/L
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Percent A (%)
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Age not given
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Reference values have not been established for patients that are less than 5 years of age.
56 – 80% (>= 5 years)
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<5 years:
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Reference values have not been established for patients that are less than 5 years of age.
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> or = 5 years:
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56 – 80%
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Interpretation is provided with report.
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Critical Values:
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N/A
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Limitations:
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Serum assay results are not valid on pregnant females and will not be run. The recommended test for Tay-Sachs carrier screening (regardless of gender or pregnancy status) is Hexoaminidase A and Total, Leukocytes/Molecular Reflex.
Because of the nature of Tay-Sachs screening, it is imperative that abnormal results reach the physician promptly for purpose of genetic counseling, and also so that alternate specimens can be considered without delay. Therefore, Mayo Medical Laboratories requires the name and phone number of the ordering physician to accompany the specimen.
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Methodology:
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Heat inactivation, Fluorometric, Automated
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References:
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Mayo Medical Laboratories August 2011
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