Hello guys. Hope you guys enjoy your SIP. As for me, im adapting to it. =) anyway, I was attached to Immunoassay section for 2 whole weeks, which was from week 2 to week 4. The immunoassay section was the area where the patients’ blood was analysed for presence of foreign antibodies and antigens in the body, such as anti-HIV, HbsAg and Anti-Hbs (Hepatitis B panel). Autoantibodies were also analysed to detect autoimmune disorders. Examples of the autoantibodies were such as Anti-Tg and Anti-TPO autoantibodies.
Hormones and crucial vitamins such as TSH, FT4, B12 and Folate were also measured by the machines in the immunoassay section. At certain times, blood was also tested for drug levels. Examples of the drugs were such as Theophylline, Digoxin and Phenytoin. Myeloma screen was also carried out when requested. This was to screen for cancer cells in the patient’s blood.
There were a total of 2 machines in the immunoassay section. The first machine was called Architech i2000 Analyzer. The second machine was known as Architech Ci8200 Analyzer.The Architech analyzers allowed multiple processing where all sample processing activities were performed. The analyzers could be configured to process sample by using potentiometric and photometric methods and / or CMIA (Chemiluminescent Microparticle Immnunoassay) methods.
The Ci8200 Analyzer comprised of both i2000 and c8000 analyzers. C8000 analyzer used photometry methods. The methods were the end-point assay and rate assay. The end-point assay was reactions that reached equilibrium and it was at that time there was little or no further change to the absorbance readings. Therefore, the system measured the absorbance readings used for calibration and calculating results. The rate assay was reactions that measured the constant change in absorbance over time. The system performed readings many times during this timing and calculated the absorbance change.
The i2000 Analyzer used the CMIA method where microparticles were mixed with the sample in the reaction vessel. During incubation, analytes present in the sample attached to the corresponding capture molecules on the microparticles which then formed the immune complex.
This analyzer measured the B12, Folate, TSH, FT4 and Ferritin levels in the patient’s blood.
Whereas for the ci8200 Analyzer ran more complex tests on the patients’ blood. The type of tests has been mentioned in the first paragraph.
The machines must underwent 5 important steps daily. The five steps were:
1) daily maintenance
2) check the supplies and reagents
3) calibrate the reagents where necessary
4) run controls
5) run patient’s tests
Controls that were run were all serum-based and in order to make sure the controls were not ‘out’, we followed the Westgard Multirule.
Both machines ran tests by measuring the serum of the patient’s blood. Before the tests were run, the blood specimens were centrifuged for 5mins so as to separate the serum and the blood. At the end of 5min, the serum would appear on top of the blood.
Whenever the serum was insufficient, it was poured into an adaptor tube so as to allow the probe of the machine to touch the serum and thus carry out the specific tests. One more thing to add, when the tests were already run, it took 20 minutes for the results to be released. The results would determine whether they were out of range or normal. Please feel free to ask me questions. Thank you!
Siti Nurfatin
0605853A
14 comments:
hello
i'm just curious, what is the difference between potentiometric and photometric methods?
thanks
rusydiana
Hi Siti,
Can you elaborate more on the potentiometric method? Thanks
Jean Leong TG02
Hi fatin
What is CMIA, Chemiluminescent Microparticle Immnunoassay, method used for? and how does it work?
Thanks
Ernest
TG01
hello, can you explain the Myeloma screen a little more? like what is done and under what conditions are the cells considered cancerous? maybe you could tell me about the staining too.
-cornelyus
hey!
wah tts so cool.. our lab if doesn't have enough serum must ask the patient to draw his/her blood again :P
Anw you mentioned blood was tested for drug level... Is it using Ci8200? And does it test for specific drugs?
And can Ci8200 Analyzer do all e immunology tests? Is there any maunal methods that you perform in your lab?
thanks!
cheers,
huimin
tg01 =)
hey rusydiana and jean, potentiometric method is a method which uses an electrode detector to analyse the specimens. this electrode detector is made of metal and gives a voltage response to the specific molecule that is detected in the specimen. whereas for the photometric method, the intensity of transmitted light is measured together with stray light to form a single signal.this signal makes it possible for the measurement of the particular molecule in the specimen.
hey earnest, one of the uses of CMIA is to detect presence of autoantibodies in the body. for example, detection of IgG class of anti-TPO (thyroid peroxidase autoantibody) in the body is done by using CMIA. when anti-TPO is detected, the patient is diagnosed with autoimmune thyroid disease. CMIA is a two-step assay where TPO-coated microparticles are combined and incubated.first step, Anti-TPO present in the specimen binds to the TPO coated microparticles. secondly,after they are bound, they are washed and pre-trigger and trigger solutions are added to the reaction mixture.this will cause a chemiluminescent reaction which is measured by relative light units (RLU). hope this answers ur question.=)
Hi Fatin,
Hope you have adapted to your workplace! =)
I have 3 questions to ask you:
1)What are the main similarities and differences between the tests conducted to screen for anti-HIV, HbsAg, Anti-Hbs (Hepatitis B panel)as well as autoantibodies? What are the principles for these tests?
2)Can you enlighten me on what is FT4? What is the significance of measuring FT4 levels in blood? Maybe u may want to provide the reference range for FT4 and other hormones and vitamins u have mentioned. What diseases can low/high FT4 lead to and the pathogenesis of these diseases?
3)If anti-Tg is tested positive, what immune disorder does the patient suffer from? What is the pathogenesis of the immune disorder? What are the confirmatory tests (if any)to confirm for the presence autoantibodies such as the two you have mentioned?
Thankz alot!
Han Yang
TG01
hey cornelyus, in my area, when myeloma screen is requested, we only run the controls for the myeloma screen and load them in the ci8200. when the controls are within the SD, we can run the patient's test for the myeloma screen. since u ask about the conditions the cells become cancerous, they are not done in the immunoassay section. In my section, there are no staining or any manual methods being carried out. Staining is usually carried out in the haematology section.
hey huimin, haha. yes, but when the serum is too little for the probe to touch the serum even with the help of the adaptor tube, we have to request the patient's blood sample again. and to answer your question, yes, drug tests are done in the Ci8200. Ci8200 tests for all kinds of drugs in the blood.but the controls for the drugs are not run first thing in the morning unless there's a request for a specific drug test. this is because drug tests such as phenytoin and theophylline are not requested on a daily basis. and thus, the controls run for the drugs daily will go to waste if the drug tests are not requested. Ci8200 does all the immunology tests except for tests like ferritin, TSH, folate, B12 and FT4. these tests are specifically done in i2000 analyzer. no manual methods are done in this section.that includes staining.hope this clarifies ur doubts!
Hey han yang, for the first question, the similarities between tests for HbsAg , anti-Hbs,Anti-HIV and Autoantibodies are that all the controls that are run are serum-based. The controls for autoantibody detection comprises of anti-Tg and anti-TPO.
These serum-based controls are kept in the fridge at 8deg Celsius high. All these controls have positive control, negative controls and in-house controls. The differences between the above tests when Anti-HIV is tested positive, the patient’s test is run again to make confirmation. When it turns out to still be positive, the results and sample are sent out to another hospital to undergo more confirmatory tests. Whereas for Hepatitis B panel, when the results show positive they are released straight away.
FT4 is known as free thyroid hormone. It is free because the thyroid hormone is bound to protein molecules. FT4 tests are usually carried out to analyse and measure the level of free thyroid hormone. When FT4 is low, the patient may be suffering from hypothyroidism and when the FT4 level is high, the patient may be suffering from hyperthyroidism. Hyperthyroidism is a condition where the thyroid gland produces to much thyroid hormone. this could be caused by multinodular goiter. Thyroid cells will cluster together and trap excess iodine. Therefore these cells produce excessive thyroid hormone. this leads to hyperthyroidism. Hypothyroidism is caused by lack of thyroid hormone produced. This is due to lack of iodine intake. This condition is also caused by thyroiditis. The reference range for FT4 is 0.8-1.5 ng/dl. Whereas for TSH, the reference range is 0.4-4.5 mIU/L. the reference range for Vit B12 is 120-680 pmol/L, ferritin is 18-250 ng/mL.
When anti-Tg is tested positive, the person may suffer from Hashimotothyroiditis. Patients suffering from Hashimoto thyroiditis have antibodies to various thyroid antigens, the most frequently detected of which include anti-Tg and anti-TPO. This disease occurs when there is a destruction of thyroid cells by cell- and antibody-mediated immune processes. This leads to the thyroid gland turning goitrous. The confirmatry test done to identify anti-Tg and anti-TPO is via immunochromatography which is inbuilt in the architect analyzers. Hope this helps!
Hi Fatin
Seems like its alot of work.
You mentioned the 5 main steps, how long does it take to accomplish the 5 steps? And also, how many controls are used in a run, and how long can the be used before they are deemed inaccurate?
Thanks
Johan
TG01
hey johan, didn't expect another question here. haha. anyways, those 5 steps took about an hour to complete, provided that there was no inaccuracy of the controls that were run. there were about 10 controls run in a machine excluding the drug controls. the controls lasted for a day before they were renewed the next day. hope this answers ur questions!
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