Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
G6PD is an enzyme that protects red blood cells from oxidative damage. Without it they are vulnerable to haemolysis. Triggers for damage can include anti-malarial medication and antibiotics. G6PD deficiency can also cause prolonged jaundice in newborns. The gene is on the X Chromosome and so the disorder affects more males than females. Females with one faulty X chromosome can usually produce enough enzyme to avoid symptoms, given an equivocal result on the screening test
Specimen container paediatric:
EDTA – Purple/Pink top
Specimen container adult:
EDTA – Purple/Pink top
Minimum volume paediatric:
1ml – Volume covers G6PD screen and possible send away for G6PD assay
Minimum volume adult:
1ml – Volume covers G6PD screen and possible send away for G6PD assay
Special requirements:
Testing should not be requested on patients who are within 4 month post red cell transfusion as this will impact on validity of results. External hospital patient requests – All requests should be sent with a copy of the patients full blood count results which must include a reticulocyte count to allow for accurate interpretation of G6PD screen.
Sample stability:
7 days stored between 2 to 26 oC
Transport requirements:
Internal patient requests – Samples should be sent ambient and within 24 hours of sample being taken to allow completion of full blood count and reticulocyte count prior to testing for G6PD screen.
External patient requests – Samples should be sent ambient within 7 days of sample being taken.
Freq Analysis:
Monday-Friday completed daily within routine hours, Saturday, Sunday and Out of hours completed ad hoc for clinically urgent requests only
Add on test:
All urgent add ons via telephone, phone extension 24766 for protein laboratory or 25819 for RVI haematology must be confirmed via email to the appropriate email address:
[email protected] (internal)
[email protected] (external)
Quality Assurance:
Participate in UK NEQAS Red cell enzymes scheme
Interpretation:
Any patients with suspected equivocal or deficient levels of G6PD will have a quantitative assay performed by Synnovis at Kings College Hospital in London. Any samples which may show to have impact on screening result due to raised reticulocyte count, platelet count or white cell count will also be sent for confirmation quantitation testing.
Reference ranges:
G6PD screen – Not applicable. Results are Normal, Equivocal, Deficient.
G6PD quantitative assay completed by Kings college London = 6.6-13.8IU/g Hb
Factors Affecting Result:
Raised reticulocyte count, platelet count or white cell count may impact on interpretation of results. Red cell transfusion will impact on validity of result.
Other info:
Samples being sent from external hospitals should be sent with a full blood count report which includes a reticulocyte count.