Hey guys, before I answer any question, I would like to apologise about one mistake that I have made. I mentioned PMS in my previous post I said that it stands for Personal Security Manager. Actually it means Process System Manager. Sorry about that.
Why is G6PD commonly done on newborns and what are the symptoms involved?
G6PD deficiency is an inherited condition due to gene defects. As this condition is silent (not much symptoms) and G6PD also plays an important part in metabolic pathway of RBCs (anaerobic respiration), an early detection will allow both patient and the doctor to know what are the thing that patient should avoid such as medication, certain strenuous exercise and contact with certain stuff or even infection so as to prevent the worsening of the condition.
Basically the patient behaves like any normal person. They do not display any symptoms unless they touches some things or took certain medications that they should avoid. Only then will they display symptoms of one who has hemolytic anaemia, example difficulty in breathing, paleness, tiredness, rapid heartbeat. However, once the trigger is removed or resolved, the symptoms of G6PD deficiency usually disappear fairly quickly, typically within a few weeks. Because we want to avoid this symptoms from happening, some hospitals actually include G6PD as a test in a newborn package.
Examples of some things that G6PD-deficient patients should avoid: aspirins, moth ball (contains napthalene that is harmful, can cause RBCs destruction in patients).
Why G6PD occurs mostly in males than females?
G6PD is inherited as an X-linked recessive trait. There is a mutation in teh X chromosome in which will affect the production of G6PD for metabolism. For females, it is very rare to find a complete deficient case as it has to have mutation in both X chromosomes. Even if they have only just one defect X chromosome, they will only be a carrier. However, for males, just a defect in the X chromosome and they will inherit this deficiency.
What is the metabolic pathway that G6PD is involved in?
The metabolic pathway is happening inside RBC. G6PD is an enzyme that catalyses the conversion of glucose-6-phosphate and NADP to gluconate-6-phosphate and NADPH. NADPH is important because it actually yield 3ATP. Therefore patients with G6PD deficiency cannot carry out anaerobic respiration.
What is the principle of the test and what cause the blood mixture to fluoresce?
The test makes use of the metabolic pathway mentioned above. The reagent actually contains glucose-6-phosphate, NADP and some other components. When the patient's blood contain G6PD, it will be able to convert the NADP to NADPH. It is teh NADPH that cause the fluorescence under UV.
Is there a difference in the intensity of fluorescence between the 1st, 2nd and 3rd drops?
Yes, there is! The 1st drop is always lighter because of the short reaction time. By the 2nd and 3rd drop, clear fluorescence should be seen.
To Zahirah,
Yes, the Neg control is a commercial blood. It is specially prepared by the manufacturer such that it contains no G6PD. If it is positive, we will definitely change it and use a new one. We will check on teh amount of reagents left in the analyser two times a day. Therefore, we have never met with a situation where there is not enough reagent. Furthermore, we also put in extra set of reagents for those tests that are commonly requested such as HIV, renal analytes.
The purpose of centrifuging is because these chemistry analytes are found in the serum and so centrifuging will separated the serum from the blood cells.
To Jue Xiu,
Modular P and E run all sorts of tests. Basically it anything that are chemistry. For example, lip profile (LDL, HDL, Cholesterol), renal screen (Na, K), HIV, HBs Ag, Anti-Hepatitis A Virus). It should be similar to the test you done in your lab just that we use different machine.
Sally
2 comments:
Hi Sally;)
today i just did the G6PD test. you said the intensity of the 2nd and 3rd drops are more brighter than the 1st drop due to the short reaction time rite? i understand that there is an incubation time before the result reading. about 10 mins? will prolonging the incubation time affect the reading? will it give a false positive result? eg. an intermediate result becomes a postive result?
CASS
TG02
Hi Cass,
That's a good qns! Yes there is an incubation time. But prolonging incubation will not affect the result (mentioned in the test kit insert too)unless teh paper is still not thorughly dry and you will have to prolong the incubation time. This kit is sensitive and very direct. If the patient's RBCs have G6PD, the drops will definitely fluoresce irregardless of how long you incubated, if G6PD is absent, even if you left the paper in the incubator for half an hour, there will not be any fluorescence seen. Let me share an experience with you. There was a Saturday where i have to work and I came upon this patient's result which showed partial fluorescence after incubated for 15 min. At first, my colleague and I decided to report it as partial G6PD deficient. But after checking the patient's gender and further incubated for another 10 min, we realise that it is not possible and making sense to report as partial deficient because the patient is a male and after the incubation the drops all fluoresce because previouly the paper is not dry yet, thus causing a false partial neg result. So, sometimes we have to be careful when coming up with the result. Hope i answer your qns!
Sally
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