Test Overview
Test Methodology

Heat Inactivation, Fluorometric, Automated

Test Usage

Preferred test to order for Tay-Sachs disease, carriers of Tay Sachs, Sandhoff's disease, and carriers of Sandhoff's.

Reference Range *

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.

Test Limitations

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.

Test Details
Days Set Up
Monday, Wednesday, Friday
Analytic Time

2 - 5 days

Soft Order Code
MiChart Code
Hexosaminidase A, Total, with Molecular Reflex
Reference Laboratory
Mayo NAGS (8774) Serum, NAGR (82943) Leukocytes with Molecular Reflex, NAGW (8775) Leukocytes
Special Testing
Specimen Requirements
Collection Instructions

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.

Special Handling

Fasting specimen.

Hexosaminase A and Total, Serum (NAGS), is contraindicated in pregnant females. During pregnancy the total hexosaminidase in serum is increased and the percentage of hexosaminidase A appears to be decreased, resulting in a false positive carrier result. In leukocytes, pregnancy does not elevate total hexosaminidase, therefore leukocyte hexosaminidase testing is recommended during pregnancy.
Normal Volume
Serum: 1 mL serum; Leukocytes: 7.0 mL ACD (solution A or B) whole blood
Minimum Volume
Serum: 0.5 mL serum; Leukocytes: 5.0 mL ACD (solution A or B) whole blood
Additional Information

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.

CPT Code
83080 per specimen
Fee Code
20045 NAGS, 20424 NAGW, 32125 NAGR
Reflex CPT
81255 TSD
Reflex Fee Code
22003 TSD
NY State Approved