Hexosaminidase Testing
General
Synonym/Acronym:
TSD (Tay-Sachs disease) testing.
Rationale
To assist in diagnosing Tay-Sachs and Sandhoff disease by identifying a hexosaminidase enzyme deficiency.
Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction.
Normal Findings
Method: Fluorometry for enzyme assay, polymerase chain reaction (PCR)/primer extension for molecular assay.
Plasma Enzyme Assay Conventional Units | Plasma Enzyme Assay SI Units (Conventional Units × 0.0167) | ||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Hexosaminidase Total | 589–955 nmol/hr/mL | 9.83–15.98 nmol/hr/mL | |||||||||||||||||||||||||||||||||||||||
Hexosaminidase A | 55%–76% of total hexosaminidase | 55%–76% of total hexosaminidase | |||||||||||||||||||||||||||||||||||||||
Whole blood leukocyte assay: greater than 62% | Molecular assay: Negative for HEXA gene mutations | Molecular assay: Negative for HEXB variants | |||||||||||||||||||||||||||||||||||||||
Methods vary, reference ranges vary; the reference range and interpretive summary provided in the laboratory report should be used to properly evaluate results. Carrier values are approximately half of the expected normal values. |
Critical Findings and Potential Interventions
N/A
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Citation
Van Leeuwen, Anne M., and Mickey Lynn. Bladh. "Hexosaminidase Testing." Davis's Lab & Diagnostic Tests, 7th ed., F.A. Davis Company, 2017. Nursing Central, nursing.unboundmedicine.com/nursingcentral/view/Davis-Lab-and-Diagnostic-Tests/425267/all/Hexosaminidase_Testing.
Van Leeuwen AMA, Bladh MLM. Hexosaminidase Testing. Davis's Lab & Diagnostic Tests. F.A. Davis Company; 2017. https://nursing.unboundmedicine.com/nursingcentral/view/Davis-Lab-and-Diagnostic-Tests/425267/all/Hexosaminidase_Testing. Accessed September 7, 2024.
Van Leeuwen, A. M., & Bladh, M. L. (2017). Hexosaminidase Testing. In Davis's Lab & Diagnostic Tests (7th ed.). F.A. Davis Company. https://nursing.unboundmedicine.com/nursingcentral/view/Davis-Lab-and-Diagnostic-Tests/425267/all/Hexosaminidase_Testing
Van Leeuwen AMA, Bladh MLM. Hexosaminidase Testing [Internet]. In: Davis's Lab & Diagnostic Tests. F.A. Davis Company; 2017. [cited 2024 September 07]. Available from: https://nursing.unboundmedicine.com/nursingcentral/view/Davis-Lab-and-Diagnostic-Tests/425267/all/Hexosaminidase_Testing.
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