Heat Inactivation, Fluorometric, Automated
Preferred test to order for Tay-Sachs disease, carriers of Tay Sachs, Sandhoff's disease, and carriers of Sandhoff's.
HEXOSAMINIDASE TOTAL, LEUKOCYTES: <=15 yrs: >=20 nmol/min/mg, >=16 yrs: 16.4 - 36.2 nmol/min/mg; HEXOSAMINIDASE PERCENT A, LEUKOCYTES: <=15 yrs: 20 - 80% of total, >=16 yrs: 63 - 75% of total; HEXOSAMINIDASE TOTAL, SERUM: <=15 yrs: >=20 nmol/min/mL, >=16 yrs: 10.4 - 23.8 nmol/min/mL; HEXOSAMINIDASE PERCENT A, SERUM: <=15 yrs: 20 - 90% of total, >=16 yrs: 56 - 80% of total.
Total hexosaminidase is increased in pregnancy due to the significant appearance of a third heat-stable enzyme. Serum results are ambiguous on pregnant females and will not be run.
2 - 5 days
MALES (serum): Collect specimen in a red top tube from a fasting patient. Centrifuge, aliquot serum into a plastic vial and freeze (do not refreeze thawed serum). FEMALES (leukocytes): Collect blood in 7 mL yellow top tube (ACD) solution A or B from a fasting patient. Refrigerate intact ACD tube (frozen ACD tube is unacceptable). ACD specimen must arrive within 48 hours of collection.
The preferred test for both pregnant and non-pregnant females is Hexosaminase A and Total, Leukocytes with Molecular Reflex (NAGR). If females wish screening for carrier status of hexosaminidase A deficiency, they must be tested prior to pregnancy. If the female is pregnant, we strongly suggest that her mate be tested for carrier status. Positive (or ambiguous) findings in the mate indicate a second order test on the female with leukocyte preparations. Please specify Hexosaminase A and Total, Leukocytes with Molecular Reflex (NAGR), Hexosaminase A and Total, Serum (NAGS), or Hexosaminidase A and Total, Leukocytes (NAGW). Leukocytes with Molecular Reflex assay includes leukocyte testing; if these results are abnormal (<63% Hexosaminidase A), Tay-Sachs Disease Mutation Analysis (Mayo TSD) will be performed at an additional charge. By ordering this test the clinician acknowledges that additional reflex testing will be performed and billed at a separate additional charge if indicated. Test sent to Mayo Medical Laboratories.