Specimen

Blood

Collection Medium:

Minimum:

Preferred minimum: 5 mL heparinized whole blood from fasting patient
Absolute minimum: 2 mL heparinized whole blood from fasting patient

Rejection Criteria:

Sample must be received at reference laboratory within 48 hours of 
collection, collect Monday through Thursday only; do not collect on 
Fridays, holidays, day before a holiday, or weekends. Specimen cannot 
be frozen.

Delivery Instructions:

Submit specimen to laboratory as soon as possible after collection.

Specimen
Instructions:

Collection date is required on request form for processing; include 
type of specimen sent (heparinized whole blood) on request form.

Testing Schedule:

Testing performed on Tuesdays.

Analytic Time:

2 weeks

Reference Range:

<2 years:                         20.1-79.8 mU/g Hemoglobin
Greater than or equal to 2 years: 12.1-39.7 mU/g Hemoglobin

Comments:

Whole blood to be washed at reference laboratory.  If specimen cannot 
arrive within 48 hours, please send washed erythrocytes.  Draw blood in 
a green top (heparin) tubes(s) from a fasting patient (4 hour 
preferred, nonfasting acceptable), and send 5.0 mL of heparinized whole 
blood refrigerated.

Clinical information:
Three clinically important inborn errors of galactose metabolism that 
result in galactosemia have been described.  The genetic disturbance is 
expressed as a deficiency of galactokinase, galactose-1-phosphate 
uridyltransferase, or UDP galactose-4-epimerase, the enzymes catalyzing 
the reactions in converting galactose to glucose.  The transferase 
deficiency is the most common.  Galactokinase deficiency results in a 
milder variant of galactosemia than that which results from GALT 
deficiency.  The epimerase deficiency is like the kinase deficiency and 
is much more rare than the transferase deficiency.

Useful for:
Diagnosis of the second most common cause of galactosemia (ie, 
galactokinase deficiency).

Interpretation:
Values <20.1 mU/g of hemoglobin suggest galactokinase deficiency.

CPT Code:

82759