Hi people!
Due to some miscommunition and confusion between the ever-busy medical technologists, this posting has been delayed. Sorry for the inconvenience caused!
Recap
Do u guys still remember what test did Adrian share about in his previous post? Yes, thats right! G6PD screening! (see week's 6 posting for the test in detail.)
After reading his post, you will wonder what happens after the patient has been screened G6PD-deficient (no fluorescence) of intermediate (having weak fluorescence). Since his workplace does not perform the next confirmatory step, he has to send it over to the lab I work in for G6PD quantitation. G6PD quantitation is the measurement of the ACTUAL G6PD enzyme level of the patient, while the initial screening only indicates "deficient", "intermediate" or "normal".
In other words, the initial screen is only QUALITATIVE, while the confirmatory test is QUANTITATIVE.
Today, I shall put an ending to the G6PD testing story by explaining the QUANTITATIVE aspect of G6PD testing.
Glucose-6-Phosphate Dehydrogenase (G6PD) Quantitation, Blood
Principle
The screening test for G6PD is based on the following immunofluorescence principle:
Glucose-6-Phosphate + NADP+ ----( G6PD)----> Gluconate-6-phosphate + NADPH (Fluorescence) + H+
G6PD (Glucose-6-Phosphate Dehydrogenase) catalyzes the oxidation of G-6-P to Gluconate-6-phosphate and simultaneously reduces NADP to NADPH. The formation of NADPH is monitored under 340nm. The rate of NADPH formation is proportional to the G6PD activity.
Procedures
Preparation of RBC haemolysate
1. Wash the EDTA blood 1 time with 0.9% saline.
2. Centrifuge to pack the cells at 3000rpm for 10 minutes.
3. Remove the saline and buffer coat completely.
4. Pipette 200 uL washed spun cells into 200 uL normal saline to obtain 1:1 RBC suspension. Mix well.
5. Pipette 50 uL of this 1:1 suspension into 250 uL of 1% saponin for lysis.
6. Mix well and stand for 2-80C for 10 minutes.
7. The haemolysate is ready for testing.
Aliquot the haemolysates onto autoanalyzer cups and load onto analyzer.
Clinical Significance
In addition to hemolytic anemia, G6PD deficient individuals can expect several other clinical manifestations of their condition. These include neonatal jaundice, abdominal and/or back pain, dizziness, headache, dyspnea (irregular breathing), and palpitations.
Treatment
Treatments for neonatal jaundice and hemolytic anemia have existed for many years. These treatments insure that the body tissues will be provided with enough oxygen by the red blood cells. Infants with prolonged neonatal jaundice are placed under special lights, called bili-lights, which alleviate the jaundice. When an anemic episode occurs, individuals are treated with nasal oxygen and are placed on bed rest, which may afford symptomatic relief. Anemic individuals are sometimes treated with human haptoglobin products, and/or blood transfusions. In acute hemolytic anemia, patients are administered folic acid.
Last Words
Thats all folks! All the best for ur MP! Remember to get plenty of rest and water! :)
Kent Lieow
TG01
0503261J
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4 comments:
hello kent,
what do you mean by quantitative aspect? is it something like- the severity of G6PD deficiency?
thanks :)
phuiyuen
tg02
hey
am jus asking out of curiosity.how does the bili-lights alleviate the jaundice??
Vinodhini
TGo2
Hello kent,
Sorry for asking a very lame qns, but what is the relation between jaundice and G6PD deficiency?
Hahaha *faints*
Thanks!! =D
Hi people, thanks for taking the time to go through my post!
To Phuiyuen,
You are absolutely right! When screening results indicates that a patient is "deficient" or "intermediate", we want to further assess how deficient the patient is by measuring the exact enzyme level (u/dL).
To Vino,
Phototherapy (with bii-lights or even sunlight!) is the process of using light to eliminate bilirubin in the blood. These light waves are absorbed by the baby's skin and blood and change bilirubin into products which can pass through their system.
The treatment is only used for a few days until the liver is mature enough to handle the bilirubin on its own.
To "unidentified",
Thats a good question, so u can tell us who you are! =P
The G6PD enzyme helps to convert GSSG into GSG (reduced glutathione)in the pentose phospate system. GSG helps to prevent oxidative damage to the RBC hemoglobin and cytoskeleton, ensuring RBC integrity. However, without G6PD, the RBC will be more susceptible to hemolysis, which releases the heme grp in the blood. The heme grp is converted to biliverdin and then bilirubin, which leads to hyperbilirubinaemia or jaundice.
Please identify urself! =)
Hope I answered all ur questions. Feel free to ask if still in doubt!
Kent Lieow
TG01
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