Tng Wess Lee, 0702570C
Clinical Biochemistry Lab (CCHEM)
Test: Analysing RBC Folate using DXI.
The test for RBC folate analysis falls under the anaemia panel category. It is used to diagnose the specific cause of anaemia. As we know, folate is used in the synthesis for RBC. Folate deficiency would cause megaloblastic anaemia.
Clinicians request for folate test to identify the specific cause of anaemia. As Vit B12 or iron deficiency might lead to anaemia too. The reason to call for RBC folate is because RBC folate is the best indicator of long-term folate stores. A low value would indicate a prolonged folate deficiency.
Before manually loading the sample (which requires RBC Folate analysis), the blood tube is treated first. Blood is received in an EDTA tube to prevent the clotting of the red cells, as the test requires analysis through the red blood cells and not the serum. This tube cannot be loaded into the LAS system to the prepared for analysis as the EDTA tube is of a smaller size compared to plain tubes or fluoride tubes.
Prior to treatment of the blood sample. Prepared (frozen) controls are thawed. Controls come in 3 levels. There are 3 levels of controls. Level 1 (low), Level 2 (medium) and Level 3 (high). Each level contains a standard and stated value, which falls within the reference range. Controls are use to determine the accuracy of the calibration.
After controls are thawed. Treatment of patient’s sample and controls proceed.
Treatment of blood sample
1) Lyse 50uL of sample and all 3 levels of control with 1000uL lysing agent.
2) Vortex all tubes
3) Wrap lysates with aluminium foil and store them in the cupboard for 1.5hrs
4) Remove wrappings, and manually load them into DXI analyser
5) After controls are verified and passed, load patient sample to be analysed
Reference interval of RBC folate: 776-1784nmol/L
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ReplyDeleteHeys~
ReplyDeletejust wondering.. are the controls u mentioned, are they run like once daily, or every time u run the specimen, u'll run the controls as well?
also, what's the purpose of wrapping the lysates with aluminium foil and storing them in the cupboard for 1.5hrs?
thanks~
Ang Yu Hui
0702632A
hello.
ReplyDeleteok. everyday we need to run controls for this test. however, only run it once a day. the controls will only last a day.
actually, it is just stated in the protocol we wrap it with aluminium foil. but we use tissue paper as foil is expensive. we also put in into the box. i asked this qns. and the response i got was to prevent any environmental reaction such as UV.
the 1.5hrs is used to allow the lysis of red cells to occur. to allow it to fully lyse.
understand ?
wess
0702570C
hi wess,
ReplyDeletecan I know how does "environmental reaction such as UV" affect the results (basically you just store it in darkness for 1.5hours )?
LIM JIA HUI JOEY
TGO1 GROUP 2 0703605f
hi joey.
ReplyDeletesorry i took so long. apparently, they med techs were not able to answer the same qns when i asked them.
so i had to take the time to search for the answer for you.
the lysing agent is ascorbic acid. upon exposure to visible light at short wavelengths, this ascorbic acid will be reversibly oxidised, and therefore not so effective in lysing.
so yes. the lysis reaction needs to occur in a dark place. to allow lysis of most of the RBC to obtain optimal amount of folate.
Hi Wess,
ReplyDeleteMay I ask, how does the DXI analyer actually work to detect the amount of folate? How is the reading taken?
Shameema
0700486D
Hey Wess Lee :),
ReplyDeleteDoes the DXI analyer only analyzes RBC folates or is there any other tests which are also analyze by this machine?
Rachel :)
Sorry. Was busy with MP and took a while to reply.
ReplyDeleteTo Shameema:
DXI - the I stands for immunoassay. There are a wide variety of techniques of binding involved in this analyser. However, specifically for folate, it adopts a 2 step competitive binding technique.
Our prepared sample is poured into a cup to raise the minute volume of sample, to allow probe extraction of sample. The cup is then placed into the analyser. The analyser will suck a small amount of sample and place it into a reaction vessel for the test to occur.
Folate will compete with folic acid-alkaline phosphatase to bind to folate binding protein. Once they bind, the resulting complexes will then bind to mouse anti-folate binding protein which adheres itself to the solid surface of the reaction vessel. Unbound materials are washed off.
Substrate will be added, conjugate cleaves substrate to generate light which will be captured by a luminometer.
To Rachel:
Yes there are many other tests which are done on the analyser. DHEA-S,Free T4, TSH, Testosterone, Vitamin B12, Cortisol, Ferritin, PTH are some examples of analytes being analysed (Note: apologies as i didn't write down all the tests, these are some that i have remembered off-hand).
Hope this answers your questions. =)
Wess
Hello Wess,
ReplyDeleteErm according from the procedure u mentioned, lyse the 3 controls, so with means that the 3 controls, the RBCs were intect and the folate level is known...so how was the 3 Levels of controls are prepared before lysing them?
Jennifer.
Good Qns.
ReplyDeleteNo idea. No one can answer my qns unless i'm working for the manufacturing company that produces this control. HAHAHA.
I presume maybe they draw a large amount of blood, lyse and test for folate levels, and if it is of their required levels, they will keep the blood and process it to preserve it somehow. tts just my guess. give me time to find out.
my key operator of the analyser said that the controls come from the manufacturers in dried form. in which they have a set of instructions in which to how to prepare the controls for this test.
ReplyDeletei hope this clarifies yr doubt on how the control is prepared.