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Galactose-1-Phosphate, RBC

Item Value
Approval req'd? No
Available Stat? No
Test code GLT1P
Performed by Mayo
Sendout? Yes
Method Ultraviolet, enzymatic
Patient Preparation The patient should not be transfused prior to obtaining samples. If transfused sampling should be delayed for at least 1 month to make sure the transfused cells have predominantly cleared and we are only testing the patient's own cells.
Collection Instructions Samples should only be collected Monday-Friday on the day shift, before noon. If received after 12:00 noon we can not guarantee the sample will be processed.

Do not collect these samples on weekends, holidays, or evenings.
Container type Dark Green top
Amount to Collect 2 mL blood
Sample type Heparinized whole blood
Preferred volume 2 mL blood
Min. Volume 2 mL blood
Processing notes Erythrocytes must be washed within 4 hours of draw. If a sample is received after 12:00 noon refer it to Blood Bank staff to see if it can be processed the same day. If not the sample will need to be rejected.

Blood Bank will process sample as follows:
1. Centrifuge for 10 minutes at 650 x G.
2. Discard the plasma and buffy coat layers.
3. Add a cold 0.9% saline solution to the erythrocytes (about 2 times the volume of erythrocytes).
4. Mix gently by inversion and centrifuge again for 10 minutes at 650 x G.
5. Remove and discard the saline.
6 Repeat the wash steps (steps c-e) 2 more times.
7. After the final centrifugation, remove and discard the saline and a thin layer of the top cells.

Freeze sample after processing. Transport to CB frozen. Order Mayo test code GAL1P
Units µg/g Hgb
Normal range
Non-galactosemic 5-49 mcg/g of hemoglobin (<1 mg/dL)
Galactosemic on galactose restricted diet 80-125 mcg/g of hemoglobin (1-4 mg/dL)
Galactosemic on unrestricted diet >125 mcg/g of hemoglobin (>4 mg/dL)

Synonyms Gal-1-P
Stability Washed and frozen RBC's 9 days.
Turn around times 8-15 days
Additional information Galactosemia is an autosomal recessive disorder that results from a deficiency of 1 of the 3 enzymes catalyzing the conversion of galactose to glucose: galactose-1-phosphate uridyltransferase (GALT), galactokinase (GALK), and uridine diphosphate galactose-4-epimerase (GALE). 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; even with survival, long-term intellectual disability can result. 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. Females 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 approximately 1 in 30,000, although literature reports range from 1 in 10,000 to 1 in 60,000 live births.

Galactose-1-phosphate (Gal-1-P) accumulates in the erythrocytes of patients with galactosemia. The quantitative measurement of Gal-1-P is useful for monitoring compliance with and effectiveness of dietary therapy. Gal-1-P is thought to be the causative factor for development of liver disease in these patients and, because of this, patients should maintain low levels and be monitored on a regular basis. The concentration of Gal-1-P in erythrocytes is the most sensitive index of dietary control.
CPT coding 84378-90
LOINC code 38485-9
Last Updated 12/18/2014 3:57:18 PM
Entry Number 411
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