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HelpTest Code GALP Galactose, Quantitative, Plasma
Testing Algorithm
For more information see Galactosemia Testing Algorithm.
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
Plasma Na HeparinOrdering Guidance
This test is not recommended for follow-up of positive newborn screening results or for diagnosis of galactosemia. The preferred test to evaluate for possible diagnosis of galactosemia, routine carrier screening, and follow-up of abnormal newborn screening results is GCT / Galactosemia Reflex, Blood along with GAL1P / Galactose-1-Phosphate, Erythrocytes.
The preferred test for monitoring dietary therapy is GAL1P / Galactose-1-Phosphate, Erythrocytes for both GALT and GALE deficiencies.
This test may be useful for monitoring in patients with GALM deficiency.
Necessary Information
Biochemical Genetics Patient Information (T602) is recommended, but not required, to be filled out and sent with the specimen to aid in the interpretation of test results.
Specimen Required
Collection Container/Tube: Green top (sodium heparin)
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Instructions: Centrifuge and aliquot plasma into a plastic vial
Specimen Minimum Volume
0.2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Plasma Na Heparin | Frozen (preferred) | 365 days |
| Ambient | 20 days | |
| Refrigerated | 20 days |
Reference Values
≤7 days: <5.4 mg/dL
8-14 days: <3.6 mg/dL
≥15 days: <2.0 mg/dL
Day(s) Performed
Tuesday
CPT Code Information
82760
Clinical Information
Galactosemia is an autosomal recessive disorder that results from a deficiency of any 1 of the 4 enzymes catalyzing the conversion of galactose to glucose: galactose-1-phosphate uridyltransferase (GALT), galactokinase (GALK), uridine diphosphate galactose-4-epimerase (GALE), and galactose mutarotase (GALM). GALT deficiency is the most common cause of galactosemia and is often referred to as classic galactosemia. The complete or near-complete deficiency of GALT enzyme is life threatening if left untreated. Complications in the neonatal period include failure to thrive, liver failure, sepsis, and death.
Galactosemia is treated by a galactose-restricted diet, which allows for rapid recovery from the acute symptoms and a generally good prognosis. Despite adequate treatment from an early age, individuals with galactosemia remain at increased risk for developmental delays, speech problems, and abnormalities of motor function. Female patients with galactosemia are at increased risk for premature ovarian failure. Based upon reports by newborn screening programs, the frequency of classic galactosemia in the United States is 1 in 30,000, although literature reports range from 1 in 10,000 to 1 in 60,000 live births.
A comparison of plasma and urine galactose and blood galactose-1-phosphate (Gal1P) levels may be useful in distinguishing among the 4 forms of galactosemia.
|
Deficiency |
Galactose (plasma/urine) |
Gal1P (blood) |
|
GALK |
Elevated |
Normal |
|
GALT |
Elevated |
Elevated |
|
GALE |
Normal-Elevated |
Elevated |
|
GALM |
Elevated |
Normal-Elevated |
For more information see Galactosemia Testing Algorithm.
Report Available
4 to 10 daysReject Due To
| Gross hemolysis | OK |
| Gross lipemia | OK |
Method Name
Spectrophotometric/Kinetic
Forms
1. Biochemical Genetics Patient Information (T602) is recommended.
2. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.