Galactose-1-Phosphate Uridyltransferase Deficiency (Galactosemia) Workup

Updated: Nov 12, 2018
  • Author: Gerard T Berry, MD; Chief Editor: Maria Descartes, MD  more...
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Workup

Laboratory Studies

All states perform newborn screening for galactosemia. [3]

A positive (ie, abnormal) indication on the newborn screen must be followed by a quantitative erythrocyte galactose-1-phosphate uridyltransferase (GALT) analysis by a laboratory that routinely performs biochemical genetic testing and consultation.

Usually, GALT genotyping provides a specific molecular diagnosis. The most common GALT allele in whites is the Q188R mutation. The S135L mutation is common in native South Africans and in African Americans. [2, 42, 45] The K285N mutation is common in Eastern Europe. [46, 47]

A urine-reducing substances test may help. This test's results are almost always abnormal (ie, positive) in infants with galactosemia who are ingesting lactose. This is a tube test rather than a dipstick test and must be differentiated from the routine urine dipstick test for glucose.

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Imaging Studies

Patients with galactosemia may exhibit white-matter abnormalities on brain MRI. [3, 48, 49]

Pseudotumor cerebri and lethal brain edema have been detected in the newborn period. [50]

Patients may exhibit cerebral atrophy.

A minority of patients manifest cerebellar atrophy.

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Other Tests

Infants with galactosemia can become jaundiced. Hyperbilirubinemia is often unconjugated but can become conjugated later.

Urine examination reveals evidence of albuminuria and, later, a generalized aminoaciduria. Eliminating lactose-containing formula from the diet quickly resolves the albuminuria.

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Histologic Findings

Fatty infiltration and inflammatory changes initially may occur in the liver.

Portal hypertension and pseudoacinar formation occur in later stages.

Cirrhosis occurs in the final stage and is indistinguishable from other causes.

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