Principles Of Endocrine Disease And Its Assessment Flashcards
What are immunoassays governed by?
Law of mass action
What is the method for hormone measurement by immunoassay?
- Add some hormone bound to a radioactive tracer to a solution with the receptor
- leave it sit for a bit
- separate out the bound and unbound hormone
- measure amount of tracer in both to see the ratio of bound: unbound
How often do you remake hormone measurement immunoassay standard curves?
Every day
What are the two types of hormone assays?
Total and free
Why are total hormone assays good?
Cheap and (mainly) reliable
Why are total hormone assays bad?
Dependant on binding protein levels and not reflective of free hormone levels
When do you use a free hormone assay?
In diseased states, where protein levels may be unreliable
Why are free hormone assays good?
Representative of the active hormone fraction and not protein dependant
Why are free hormone assays bad?
Complex, expensive and can have poor reproducibility
What are the two ways you can do a free hormone assay?
Semipermeable membrane that only lets free hormones across, or add a collating agent that binds the protein together and then it falls out, leaving the free hormones to be measured
When do you use immunometric assays?
If the hormone has a really short half life in plasma
Why do you need to use the immunometric assays?
If you try to just measure one end, it will be an inaccurate measure of the amount of active hormone in circulation
How do you do an immunometric assay?
Start with one antibody attached to the edge of the test tube - add protein - N terminal binds to antibodies - wash sample (so all the unattached hormones are removed) - add second antibody
How do you test overproduction of TH?
Thyroid function, autoantibodies and technetium scanning
How do you test underproduction of TH?
Thyroid function, autoantibodies
