Galactose-1-Phosphate, RBC
Label Mnemonic: GAL1PHOS
Epic Lab Code: LAB3192
Downtime Form: A-1a Miscellaneous Request
Commercial Mail-out Laboratory
5231 RCP
356-8593
Specimen(s):
Blood
Specimen Instructions:
Erythrocytes must be washed within 4 hours of draw.
Collection Medium:
Green top tube 4 mL (Na Heparin)
Minimum:
Collect and process a minimum of 2 mL of whole blood as follows: •Immediately centrifuge for 10 minutes at 650 x G. For conversion to RPMs, see Additional Information. •Discard the plasma and buffy coat layers. •Add a cold 0.9% saline solution to the erythrocytes (about 2 times the volume of erythrocytes). •Mix gently by inversion and centrifuge again for 10 minutes at 650 x G. •Remove and discard the saline. •Repeat the wash steps (steps c-e) 2 more times. After the final centrifugation, remove and discard the saline and a thin layer of the top cells. Additional Information: For infants, collect specimen immediately prior to feeding to avoid postprandial elevations. The relative centrifugal force (G-force) can be estimated by applying the following formula: g=11.18 x r x (n/1000)(2). Where: r=radius in centimeters and n=speed in RPM. The radius from the center of the rotation axis to the bottom or outermost portion of the test tube should be used. RCF is expressed relative to the force of the earth's gravity.
Delivery Instructions:
Submit specimen to laboratory as soon as possible after collection.
Turn Around Time:
2 weeks upon receipt at reference laboratory
Reference 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)
Interpretive Data:
The concentration of galactose-1-phosphate (Gal-1-P) is provided along with reference ranges for patients with galactosemia and normal controls. The recommended Gal-1-P goal for patients with galactosemia is <125 mcg/g of hemoglobin.
Comments:
Useful For:
Monitoring dietary therapy for classic galactosemia (total GPUT deficiency), galactosemia-Duarte (GD) patients, or rarely, patients with UDP galactose-4-epimerase deficiency.

Cautions:
Not a screening test for galactosemia
Methodology:
Ultraviolet, Enzymatic

This assay is a quantitative measure of the galactose-1-phosphate and is useful for monitoring the dietary management of galactosemics. This assay should not be used for the diagnosis of galactosemia.
CPT Code:
84378