G6PD Screen

Testing Laboratory

Auckland Te Toka Tumai | Auckland Hospital

Department

Haematology

Delphic Registration Code (Alpha Code)

GPDH

Test Code (Numeric Code)

1417

Laboratory Handling

Phlebotomy

Collect 1x 4ml EDTA (Lavendar cap) blood sample.

Transport

Transport at ambient temperature (8-24°C).

Registration

Registered as GPDH

Separating

EDTA - Do not spin.

Laboratory

LabPlus Special Haematology

Test Adds Requirement

Only available as test add by Special Haematology.

Sample Stability

Reliable results may be obtained on specimens stored at 4oC for up to one week. Packed red cells are used in the test to limit contamination by G6PD isoenzymes in leucocytes and platelets and to lessen contamination from reticulocytes. Specimens which are sent overnight etc should be kept on ice.

Synonyms

glucose-6-phosphate dehydrogenase deficiency

Turnaround Time

1 day

G6PD (glucose-6-phosphate dehydrogenase) whole blood samples are typically stable for 7 days when refrigerated at 2°C to 8°C. If a sample shows deficient or intermediate results, the laboratory holds it for 5 days to allow for a confirmatory enzyme assay if requested.

Specimen Type

• Whole Blood

Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Lavender Cap)

Preferred Sample Volume (ml)

4

Minimum Sample Volume (ml)

2

No of Samples Required

1

Paediatric Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Microtainer)
• EDTA (Lavender Cap)

Acceptable

• EDTA (Microtainer)
• EDTA (Lavender Cap)

Preferred Sample Volume (ml)

1

Minimum Sample Volume (ml)

.25

Additional Specimen Information

Reliable results may be obtained on specimens stored at 4oC for up to one week. Packed red cells are used in the test to limit contamination by G6PD isoenzymes in leucocytes and platelets and to lessen contamination from reticulocytes. Specimens which are sent overnight etc should be kept on ice.

Aliquot Instructions

Sample Type

• Whole Blood

Minimum Volume (ml)

2

Transport to Lab

Ambient (8 - 24 degrees Celsius)
If overnight - Chilled (2 - 8 degrees Celsius)

Test Method

Manual Process-The Glucose-6-phosphate dehydrogenase (G6PD) fluorescent spot test is a qualitative screening method that detects enzyme deficiency by observing NADPH fluorescence under ultraviolet (UV) light.

Limitations / Interference

Reticulocytosis can mask a G6PD deficiency. If reticulocytosis is present and G6PD deficiency is suspected, suggest a repeat screen when the reticulocyte count returns to normal.
A normal Screen test does not exclude the presence of female carrier. If clinically indicated, family studies and enzyme assays can be arranged.
A blood transfusion within the last 3 months can also make a G6PD deficiency. Suggest a screen 3 months after the most recent transfusion.
Samples with a Deficient or Intermediate result will be held for 5 days. So a G6PD assay can be arranged if required, please contact: Special Haematology (Ext.22065)

Uncertainty of Measurement

False negatives and positives

G6PD screening is indicated to check newborns who develop severe or unexpected yellowing of the skin shortly after birth.
The most dangerous consequence of G6PD deficiency is neonatal icterus (if untreated, mental retardation may result). The jaundice may be due to impairment of liver function, presumably because of a deficiency of the enzyme in the liver (G6PD deficiency is not limited to red cells – G6PD activity in platelets, leucocytes, saliva and liver cells may also be reduced).

Contact Information