hello future med techs. hehe....
hope ur attachment's going fine, mine's okay =)
So now, i would like to share with you a test that is simple but yet important that is done in the Biochemistry Lab.
Test name: G6PD Screening
First, lets just briefly recap on what G6PD is. Glucose-6-phosphate dehydrogenase, G6PD, is a key enzyme needed for the hexose monophosphate pathway which produces NADPH, essential for erythrocyte membrane integrity.This condition might result to destruction of RBCs, leading to hemolytic anemia, followed by jaundice. Thus, for newborns with jaundice, they have their blood sampled to check if the baby's jaundice is caused by G6PD deficiency.
How the test is done:
Patient's sample collected in EDTA tube to prevent clotting.
Patient's tube is overturned 2-3 times to ensure a homogenous composition when sample is taken out.
Using a pipette, 5 microlit of patients whole blood was transferred onto a seperate tube containing 100 microlit of reagent that contains G6-P and NADP.
The mixture is left to sit for 5 minutes.
Below is an equation for the reaction that should take place in the presence of G6PD:
10 microlit of mixture is pipetted out and transferred onto a filter paper.
The filter paper is dried for ten minutes and then viewed under long UV wave in the ulraviolet viewing cabinet.
As seen from the equation above, G6PD is needed for the reaction to take place. The presence of G6PD can be known by viewin the filter paper under the UV light in the ultraviolet viewing cabinet. NADPH flouresces under long wave UV light and a flourescence would indicate the presence of G6PD. In contrast, a sample that does not contain G6PD would not give out any flourescence when viewed under the long wave UV light.
4 controls are set up at the same time:
1. G6PD deficient
2. Intermediate G6PD deficient
3. Bblank (only reagent present)
4. G6PD present
The controls are used as a guide for the patient's results.
For example, a G6PD deficient control does not flouresce at all while an intermediate G6PD control floureses slightly. From the controls, we can gauge the if the patient is completely deficient of G6PD or an intermediate case.
However, this test is just a screen. Samples of patients with positive results are sent out to another laboratory in a hospital for further testing.
feel free to ask ny questions. hope you like my post =)
raihana~
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6 comments:
hihi,
you mentioned that NADPH is essential for erythrocyte membrane integrity, do you know any other ions that is essential for the integrity for erythrocyte membrane?
you also mentioned that the G6PD screening is just a screen, further testing have to do when there is a positive result, so what are some example of the further testing ?
THANK YOU=)
TINGJIE
0608495H
TG02
hey raihana,
may i ask, is it possible that someone is screened positive for the test but when further testing is conducted, it states otherwise? if that happens, then how would you troubleshoot it and which information is then reliable?
also you mentioned 10 microlit of mixture is pipetted out and transferred onto a filter paper then dried for ten minutes and then viewed under long UV wave, why do you have do dry it and not visualize it as it is.
Thanks alot
Liyanah Zaffre
0607718D
TG02
Hey Raihana,
Why do u leave the mixture for 5minutes? What if you leave it for a longer or shorter period? Would it affect the result?
And does every request for G6PD screening would require a control to run with it?
Thank You
Dyana
0605169B
Hey raihana,
I would like to ask, why do you need to leave the mixture to sit for 5 mins and when the filter paper is left to dry for 10 mins, do we need to place in on a hot plate or leave it to surrounding rtp?
Debbie
TG02
are hitachi cups like special sized cups with special functions? or are they just cups manufactured by hitachi? I'm judst wondering cuz you seem to place special emphasis on the word HITACHI.
cornelyus
answers:
to ting jie:
i am afraid ur first question is more on the molecular side which i find it difficult to find an answer, i recommend u ask a lecturer =)
for the second qn, the test would be a quantitative testing done at another General Hospital in Singapore.
to liyanah:
yes, it is possible probably because the person is not trained, and theresfore his/her techniques might lead to a wrong result being produced.
also, NADPH only can flouresce well if the mixture is dry. if is stil wet, it might lead to a false reading.
to dyana:
the mixture is left for 5 minutes to ensure the reagent and the ions in the blood can proceed with the desired chemical interaction. its is ok to leave it a little longer but not shorter because the interaction time might not be sufficient.
and no, we run a control for every batch that is being run at the same time, not for every sample.
to debbie:
we leave it to sit for 5 mins to ensure the reagent and the ions in the blood can proceed with the desired chemical interaction.
also, we bake in an oven.
i apologize for the late reply.
raihana~
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