Test Catalog

Test ID: BGAW    
Beta-Galactosidase, Blood

Method Description Describes how the test is performed and provides a method-specific reference

Whole blood collected in ACD or EDTA anticoagulant tubes is spotted onto filter paper and dried overnight. A one-eighth inch (3-mm) disk is punched out of the dried blood spot (DBS) into a 96-well, round-bottom plate with citrate-phosphate buffer as elution liquid and 4-methylumbelliferyl-beta-D-galactopyranoside in water as the substrate. A blank is prepared using only elution liquid, substrate, and filter paper punches containing no blood. All patients, controls, and blank are set up in duplicate. After the incubation period, the liquid from the plate is transferred to a 96-well, flat-bottom black plate. A calibration curve is 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 10.4 nmol/hour/mL. Stop buffer is added to all wells (patients, quality controls, blanks, calibrators). The plate is then read on the spectrofluorometer. Fluorescence readings for duplicate wells are averaged, and the average fluorescence is used to calculate the enzyme activity result.(Civallero G, Michelin K, de Mari J, et al: Twelve different enzyme assays on dried-blood filter paper samples for detection of patients with selected inherited lysosomal storage diseases. Clin Chim Acta. 2006 Oct;372(1-2):98-102; Cowan T, Pasquali M: Laboratory investigations of inborn errors of metabolism. In: Sarafoglou K, Hoffman GF, Roth KD, eds. Pediatric Endocrinology and Inborn Errors of Metabolism. 2nd ed. McGraw-Hill; 2017:1139-1158)

PDF Report Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) Performed Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Preanalytical processing: Monday through Saturday

Assay performed: Tuesday

Report Available The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

8 to 15 days

Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

1 year

Performing Laboratory Location Indicates the location of the laboratory that performs the test