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Order Code LABGOR, GALP Galactose, Quantitative, Plasma

Reporting Name

Galactose, QN, P

Useful For

Screening for galactosemia

Testing Algorithm

For more information see Galactosemia Testing Algorithm.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Plasma Na Heparin


Ordering 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 Special Container
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

Method Description

The formation of reduced nicotinamide adenine dinucleotide (NADH) measured by the increase in absorbance at 340 nm is proportional to the amount of D-galactose in the sample.(Kurz G, Wallenfels K. In: Bergmeyer HV, ed: Methods of Enzymatic Analysis. Vol 3. 2nd ed. Verlag Chemie, Weinheim, Academic Press. 1974:1279-1282; 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)

Reject 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.

Genetics Test Information

Galactose-1-phosphate uridyltransferase (GALT) deficiency is the most common cause of galactosemia and requires lifelong restriction of dietary galactose.

 

Plasma galactose can be elevated in patients with galactosemia caused by GALT deficiency, galactokinase deficiency, or galactose mutarotase deficiency.

 

Classic galactosemia can be diagnosed by analysis of GALT enzyme.