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Order Code LALB Lysosomal Acid Lipase, Blood

Useful For

Evaluation of patients with a clinical presentation suggestive of lysosomal acid lipase deficiency using blood specimens

 

This test is not useful to determine carrier status for cholesteryl ester storage disease or Wolman disease.

Reporting Name

Lysosomal Acid Lipase, B

Specimen Type

Whole blood


Specimen Required


Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Yellow top (ACD) or green top (sodium heparin)

Specimen Volume: 2 mL


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole blood Refrigerated (preferred) 7 days
  Ambient  7 days

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Reference Values

≥21.0 nmol/h/mL

Method Description

The whole blood specimen is spotted onto filter paper and dried overnight. A 3-mm (one-eighth inch) disk is punched out of the dried blood spot into a microcentrifuge tube, and water is added as a preincubation extraction that takes place on an orbital shaker. Extraction liquid is combined with either water (total activity well) or Lalistat (inhibited well) in a black 96-well plate. The plate is incubated. The substrate is then added to the same plate. After the incubation period, calibrators are prepared and analyzed on every plate to calculate enzyme activity results based on fluorescence units in patient wells vs calibrators. The calibration is derived from 4-methylumbelliferone (4-MU) that is serially diluted manually in the plate, with the highest calibrator being equivalent to an enzyme activity of 672.0 nmol/hour/mL blood. The plate is then ready to be read using the spectrofluorometer. Enzyme activity is calculated by subtracting the inhibited activity from total activity.(Hamilton J, Jones I, Srivastava R, Galloway P. A new method for the measurement of lysosomal acid lipase in dried blood spots using the inhibitor Lalistat 2. Clin Chim Acta. 2012;413(15-16):1207-1210; Cowan T, Pasquali M: Laboratory investigations of inborn errors of metabolism. In: Sarafoglou K, Hoffman GF, Roth KS, eds. Pediatric Endocrinology and Inborn Errors of Metabolism. 2nd ed. McGraw-Hill; 2017:1139-1158)

Day(s) Performed

Friday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

82657

Method Name

Fluorometric Enzyme Assay

Forms

1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Biochemical Genetics Patient Information (T602)

3. If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-Biochemical Genetics Test Request (T798)

-Gastroenterology and Hepatology Test Request (T728)

Genetics Test Information

This test provides diagnostic testing for patients with clinical signs and symptoms suspicious for lysosomal acid lipase deficiency (LALD).

 

LALD is expressed phenotypically as infantile-onset Wolman disease or later-onset cholesterol ester storage disease.