What is the purpose of an RIA ?
It is a technique that is used to measure low levels of antigens such as the hormone levels in the blood, using antibodies.
What is an antigen?
An antigen is a substance that causes the body to make an immune response to bacteria and viruses.
How can RIAs be used to diagnose osteomyelitis?
RIAs are used to identify whether there is an infection present, this can be used to diagnose osteomyelitis as it is caused by an infection in the bone.
What is the method for an RIA?
- A known quantity of an antigen is radioactively labelled and mixed with a known quantity of the antibody, and the two specifically bin together.
- A sample from a patient containing an unknown quantity of the same antigen is added.
- Causing the unlabelled antigen from the patient to compete with the labelled antigen to form the antigen-antibody complex.
- The bound antigens are separated from unbound antigens, the radioactivity of the bound antigen remaining is measured by a gamma counter.
- When the remaining radioactivity has been measured the results can then be recorded.
What are the limitations of RIAs?
- The human antibodies can interfere with the radioimmunoassay’s and can react either positively or negatively with the reagents to give a false result.
- Poor specificity can lead to lower sensitivity which can also lead to a false result.
- There are special requirements of a special counter for radioisotopes however, radioactive decay can cause a reduction in the number of unstable nuclei in a sample which reduces the count rate.
What is a false positive and a false negative result?
- False positive = wrongly indicates that a particular condition or attribute is present.
- False negative = wrongly indicates that are particular condition or attribute is present.
What is the purpose of haematology?
It is used to diagnose and treat patients who are experiencing disorders of the blood and bone marrow, the disorders include:
- haemophilia
- leukaemia
- lymphoma
- sickle cell anaemia
How is haematology used to diagnose osteomyelitis?
Haematology is used to help diagnose osteomyelitis because a complete blood count is needed, this is because if there is an increase in the number of white blood cells, it will indicate that an infection is present.
What is the method for haematology?
1, a blood sample is taken from the patient
2, the sample is placed into a haematology analyser which is a piece of technology that counts the different types of red and white blood cells, platelets, haemoglobin and haematocrit levels.
3, However, the full blood count can also be tested manually, the sample is placed into a haemocytometer which is a microscope slide that contains a specific volume of blood.
4, It is then secured with a standardised grip to help when counting the cells.
What are the limitations of haematology?
- it can be said that this technique is subjective, this is because it can be statistically unreliable such as it might miscount a few cells. This means that there is a lack of validity in the test.
- When counting the cells manually there can be an error for example, monocytes are often under miscalculated and lymphocytes are over miscalculated.
What is the purpose of spectrophotometry?
- This method is used to measure how much a chemical substance can absorb or transmit light.
- In clinical applications, it can be used to examine blood or spinal fluid to establish a clinical diagnosis.
How can spectrophotometry be used for osteomyelitis?
This test can be used for osteomyelitis as it can measure the concentration of bacteria in the osteomyelitis sample which is determined by using Ultra-violet spectrophotometry.
What is the method for spectrophotometry?
- Turn on the spectrophotometer as it needs to warm up to be able to give an accurate reading.
- Ensure that the test tubes are clean
- Put the appropriate volume of the sample into the test tube to ensure that the light passes through the sample and not the empty bit of the tube.
- Prepare a control solution, this is to allow for the results to be compared
- On the spectrophotometer choose the wavelength of the light to analyse the sample.
- Adjust the machine with the control sample and set the blank to 0
- Place the sample into the spectrophotometer and wait 10 seconds before recording the absorbance.
- lace the sample into the spectrophotometer and wait 10 seconds before recording the absorbance.
What are the limitations of spectrophotometry?
- The sample can be affected by environmental factors such as temperature
- it counts both living and dead cells
- Only liquid samples can be used as they are possible to analyse, this is because substances can only me measured if they have a certain wavelength.
