Test Code: G6PDa Preferred Name G6PD assay

2 days
2 days
Medicare Item
5 days

Test Tubes

ImageSpecimen TypeSpecimen VolumeTube Type
Blood (adult)2 mLEDTA 3 mL whole blood (Lavender top)
Blood (paediatric)500 µLEDTA 2 mL Paediatric ( Lavender Top)
Blood (neonatal)500 µLEDTA 2 mL Paediatric ( Lavender Top)
BloodEDTA 3 mL whole blood (Lavender top)


EDTA or lithium heparin whole blood may be used although EDTA is the specimen of choice.
G6PD screen cannot be performed post transfusion.


Red cells are likely to haemolyse only if they have less than 20% of the normal enzyme activity. G6PD activity may be higher than normal when there is an increased amount of young red blood cells, so that a genetically deficient sample may yield a value within the normal range. In practice, the following information may be of value: 1.) In males, the demarcation between normal and deficient subjects is sharp, so that diagnosis should not present difficulties in most cases. A value in the low-normal range should also raise the suspicion of G6PD deficiency (activity with reticulocytosis should be HIGHER than normal). The assay should be repeated when the reticulocyte count is normal. 2.) In females, heterozygosity can never be ruled out by a G6PD assay. However, in most cases, a normal value in a female means that she is a normal heterozygote, and a value below 10% of normal means that she is a deficient heterozygote. Any value between 10 and 90% of normal usually means a heterozygote, except for the complicating effects of reticulocytosis. A fraction of red cells in heterozygotes is as enzyme-deficient as in a hemizygous male, and therefore susceptible to haemolysis. The severity of potential clinical complications is roughly proportional to the fraction of deficient cells; therefore, within the heterozygote range, the actual value of the assay correlates with the risk of haemolysis

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