What is Radioimmunoassay and how does it work? (RIA EXPLAINED)
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- čas přidán 12. 10. 2022
- Radioimmunoassay, also known as RIA is a technique which is used to determine the concentration of antigen in a patient sample. It uses something called a hot antigen which is just an antigen plus some radioactive material. The basic principle of RIA is based on competitive binding between the *radio labeled antigen* (hot antigen) and an *unlabeled antigen* (cold antigen), with a selected antibody. The resulting radio activity is measured to determine the concentration of the target antigen, i.e. the sought after antigen.
Let us examine the technique in step-by-step fashion:
1. First the antibody is precoated in a microwell plate
2. Then hot antigen is added and after a while any unbound hot antigen is washed away
3. Next, the patient sample containing cold antigen is added
- This causes the cold antigen to out compete the hot antigen for binding to the antibody
4. Afterwards another wash is carried out and the intensity of the labeled antigen, i.e. the hot antigen is measured using a gamma counter
It is important to remember that the signal is *INVERSELY PROPORTIONAL* to the concentration of the target antigen
- High signal → low concentration
- Low signal → high concentration
Radioimmunoassay is very useful since it can be used for:
- Drug detection from blood samples
- Blood bank screening for contaminants
- Detection of cancer biomarkers
- Measurement of hormone levels
- Measurement of disease associated antigen levels
- Measurement of vitamin
Please let me know if anything was unclear to you! Love me some feedback, both good and bad!
Variable region not the constant region
Hello, so if I understand, we want to know how many cold antigen are on the solution based on their capacity to replace to hot antigen (which is radioactive), so the radioactivity will decrease if we have a lot and steady if we dont have cold antigene ?
Good explanation. I have one question, the antibodies that are used in this technic are the same used in other immunoassays? I mean those from animal origin like bovin antibodies thar are commercially available? Thank you
Based on what I have read it seems to be ordinary antibodies.
However, I could be wrong since I have not read enough on the specifics of this technique to say for certain. Just enough to understand the general idea!
I apologize that I can't be of more help! Here, are some of the articles I have read:
www.sciencedirect.com/topics/medicine-and-dentistry/radioimmunoassay
My husband had his RIA test last March 2023 and the result was 0.1, doctor said the normal range is between 0-50. Now (September 2023) he got another test again for follow up check up, and the result is 0.48. Im so worried, because he had tumor and it might come back again 😞 but the doctor said not to worry, he will have another RIA again next year March 2024. Having increase in result, does it always mean bad thing? 😰
I'm sorry to hear that you have to worry like that. I have no medical expertise so I have no idea what's considered a normal reference value when performed in that setting, nor what could cause an increase from previous values.
But I'm sure that if your doctor is telling you not to worry then there's nothing to worry about.
I truly wish you the best and I apologize I could not be of more help!♥️