Clinics and Departments

Laboratory Services

Lab Dept:

Chemistry

Test Name:

GALACTOSE–1–PHOSPHATE URIDYLTRANSFERASE

General Information

Lab Order Codes:

G1PH

Synonyms:

GPUT; GALT

CPT Codes:

82775 – Galactose-1-phosphate uridyl transferase; quantitative

Test Includes:

Galactose-1-phosphate uridyl transferase level reported as U/g of hemoglobin.

Logistics

Test Indications:

This assay is a quantitative measurement of the enzyme GPUT and provides an approximation of the patient’s genotype. A deficiency of this enzyme is the most common cause of galactosemia. A galactokinase deficiency is the second most common cause of galactosemia. Those patients with GPUT values of 10.0 U/g of hemoglobin or less should be definitively characterized by genotyping. This assay is not useful for diet monitoring of galactosemics

Lab Testing Sections:

Chemistry - Sendouts

Referred to:

Mayo Medical Laboratories (Mayo Test: FG1PU forward to ARUP)

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Daily, 24 hours

Turnaround Time:

3 – 4 days; test set up Monday, Wednesday, Friday

Special Instructions:

See Patient Preparation.
Patient History for Galactosemia Form
is required.

Specimen

Specimen Type:

Whole blood

Container:

Lavender top (EDTA) tube

Draw Volume:

7 mL (Minimum: 3 mL) blood

Processed Volume:

Same as Draw Volume

Collection:

Routine venipuncture

Special Processing:

Lab Staff: Do Not centrifuge. Specimen should remain in original collection tube. Store and ship at refrigerated temperatures. Include Patient History for Galactosemia Form. Specimen must not be frozen. Forward promptly.

Patient Preparation:

Fasting specimen (4 hour) preferred

Sample Rejection:

Specimens other than whole blood, anticoagulants other than EDTA; Heparin or ACD, gross hemolysis; frozen specimens; mislabeled or unlabeled specimens

Interpretive

Reference Range:

U/g of hemoglobin
(Note: One U/g Hb is equivalent to one umol/hour/gram of hemoglobin).

Critical Values:

N/A

Limitations:

This assay is not useful for monitoring of dietary compliance by galactosemics.

The presence of galactose in blood and urine is dependent upon dietary consumption, and this test is valid only after the patient has consumed either galactose or lactose in their normal diet.

Methodology:

Enzymatic

Contraindications:

This assay is not useful for diet monitoring of galactosemias

References:

Mayo Medical Laboratories Web Page (February 2014)

Updates:

11/21/2006: MML has removed the upper normal range value for this test. The reference range previously was stated as 18.5-28.5 U/g of hemoglobin.
2/14/2014: Test down at MML, temporary move to ARUP.



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