Alpha Glucosidase (Sendout)

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General Information

Lab Name
Lab Code
941
External Test Id
LAB2774
Description

Test Description: Fluorometric enzyme test for alpha-glucosidase for diagnosis of Pompe disease (glycogen storage disease type II).

Clinical Utility: Pompe disease (glycogen storage disease type II) is an inherited disorder of glycogen metabolism and a lysosomal storage disease, caused by a deficiency of the enzyme alpha-glucosidase (also called GAA and acid-maltase). Individuals with Pompe disease are unable to use the glycogen stored in the lysosomes for energy, resulting in the progressive storage of glycogen in the heart, liver, and skeletal muscle. Pompe disease can present in infancy with profound hypotonia, cardiomegaly and cardiomyopathy or later in childhood and adulthood with progressive muscle weakness and respiratory insufficiency. Late onset Pompe disease presenting in the second to seventh decade of life can appear with muscle weakness in the upper and/or lower extremeties, muscle weakness in the trunk and shortness of breath after exercise. This test is not appropriate for determining carrier status or for prenatal diagnosis.

Ordering Requirements: Include relevant clinical information (drug therapy, family history, etc.) in the Epic order comment to ensure proper interpretation.

Collection Note: Limited specimen stability. Time blood collections accordingly to ensure that samples reach the performing lab within the 24-hour stability limit. Failure to follow collection guidelines may result in test cancellations.

Forms & Requisitions
Synonyms
A Glu Pom, Acid Maltase, Alpha-Glucosidase, GAA, Glycogen Storage Disease II, GSD II, LAB2774, Lysosomal Enzyme, Pompe
Components

Interpretation

Method

4 MU fluorometric assay with acarbose inhibition

Reference Range
Ref. Range Notes
Specimen Type Normal Range
Blood Spot 21-85 pmol/hr/spot
FB (fibroblast) 40-155 nmol/hr/mg protein

Ordering & Collection

Specimen Type
Blood
Collection

Collection Timing:

  • Collect Monday - Thursday only.
  • Samples must be set up at the performing lab within 24 hours of collection. Expedite transport to the lab.

Sample Requirements:

  • Collect 3 mL blood in YELLOW top (ACD A or B) or DARK GREEN (Sodium Heparin) top tube
  • Also Accepted: Newborn blood spots (minimum of 3 spots) and cultured cells from skin fibroblasts (2 confluent T-25 flasks).
  • Unacceptable: Gel separator tubes
Forms & Requisitions
Handling Instructions

Outside Laboratories: Due to limited sample stability, clients should arrange for testing directly with Seattle Children's Hospital Laboratory.

Quantity
Requested: 3 mL (ACD or NaHep) whole blood
Minimum: 2 mL (ACD or NaHep) whole blood

Processing

Receiving Instructions

Store and transport whole blood at ambient temperature. Notify Sendouts staff upon receipt of samples in the lab for expedited transport.

Login: SEND1-;RM TEMP

  • RSDNT1: SEACHL
  • RSTYP1: WB
  • RTSRQ1: ;Alpha Glucosidase (SEACHL Test LAB2774)

Sendouts:

  • Order SEACHL Test: LAB2774
    • Select Pompe/alpha-glucosidase under "Lysosomal Enzymes by Disease" on the Biochemical Genetics requisition.
    • Order test LAB2775 for fibroblast samples.
  • If clinical information (drug therapy, family history) is included with the order, print the Epic requisition and send it with the SEACHL requisition.
  • Samples must reach SEACHL for set up within 24 hours of collection. Send samples as received during the day via DLMP or Delivery Express courier. Samples collected in the evening may be held for until shipment the following morning. Notify the Biochemical Genetics lab if sending a sample close to the cutoff.

Stability (Whole Blood): Ambient: 24 hours; Refrigerated: 24 hours; Frozen: Unacceptable.

  • Note: Whole blood samples received >24 hr after blood collection will still be processsed and test performed if possible.

Stability (Dried Blood Spots): Ambient: 1 week.

Misc Sendout

Performance

Lab Department
Frequency
Performed: Weekly. Turnaround Time: 7-10 days.
Available STAT?
No
Performing Location(s)
Sendout Seattle Children's Hospital Laboratories
206-987-2617

4800 Sand Point Way NE
Seattle, WA 98105

Room Number: FB.2.441
Other Locations/Notes

Seattle Children's Hospital Laboratory, Biochemical Genetics: (206) 987-2216

Billing & Coding

Billing Comments

CPT: 82657