Search our Test Catalog. Specify what to search (name, test code, titles, everywhere) and how to search (begins with, contains)

Unit Code 8765:
Galactose, Quantitative, Urine

Print Friendly View
Print Page Email Page

Useful For

Screening for galactosemia

Clinical Information

Galactosemia is an inborn error of galactose metabolism.

Galactosemia results in exaggerated plasma galactose

concentrations when affected infants consume milk products

(lactose in milk is metabolized to glucose and galactose).

Known forms of galactosemia include galactose-1-phosphate

uridyltransferase (GALT), galactokinase (GK), and uridine

diphosphate galactose-4-epimerase (UDPGal-4-epimerase)

deficiency, in order of decreasing probability.

 

The most common cause of galactosemia is deficiency of GALT.

Symptoms of untreated GALT deficiency include failure to thrive,

vomiting, liver disease, cataracts, and developmental delay.

Patients with classic GALT deficiency are at risk of life-threatening

liver and kidney failure and Escherichia coli sepsis in the newborn

period. Because of the poor prognosis of the untreated galactosemic

patient, it is imperative that treatment be instituted early. This led

to the inclusion of GALT deficiency into all newborn screening

programs in the United States. Accordingly, most patients are

diagnosed following a positive newborn screen, but physicians

must still consider this diagnosis in any patient presenting with

liver disease.

 

Galactosemia is diagnosed by specific enzyme assay when the

clinical presentation is highly suggestive of a specific deficiency

or by screening for abnormally accumulating metabolites, in

particular galactose and galactose-1-phosphate (G-1-P). The

following table indicates which metabolites are elevated in the

various forms of galactosemia as long as the patient is on a

regular, lactose-containing diet:

 

                                      Galactose                  G-1-P

Deficiency              (plasma/urine)        (blood)

Galactokinase         Elevated                        Normal

                                                                               

GALT                           Elevated                        Elevated

 

UDPGal-4-                 Normal-                          Elevated

epimerase                 elevated

Reference Values

<30 mg/dL

Interpretation

Elevated urine galactose values are found in individuals with

galactosemia.

Cautions

When urine galactose is elevated, the specific enzymatic defect

should be determined. Galactose in the urine may also be found

in severe hepatitis, biliary atresia of the newborn, and in rare

cases of galactose intolerance.

 

The preferred test for monitoring dietary therapy is #80337

"Galactose-1-Phosphate (Gal-1-P), Erythrocytes.”

Clinical Reference

Holton JB, Walter JH, Tyfield LA: Galactosemia. In The Metabolic

and Molecular Bases of Inherited Disease. 8th edition. Edited by

CR Scriver, AL Beaudet, D Valle, et al. New York, McGraw-Hill,

2001, pp 1553-1587

Key