Investigation of thyroid disorders

Question 1

What is an immunoassay?

Answer 1

use of Ab to measure low concentrations of substance

Question 2

What are the features of a competitive binding assay?

Answer 2

blood sample substance competes with sample to bind limited amount of Ab
sample is labelled - washed out
more analyte = more analyte binding Ab = less signal from labelled sample substance
(inversely proportional)

Question 3

What are the features of an immunometric assay?

Answer 3

capture Ab stuck on surface
analyte binds to capture Ab
monoclonal Ab excess - monoclonal Ab bind analyte and elicit signal
high signal = high analyte (proportional)

Question 4

What are the key tests of hypothyroidism?

Answer 4

low thyroxine (by definition)
TSH high if issue with thyroid gland itself
TSH low if issue with pituitary (secondary hypoparathyroidism)

Question 5

What are the key tests of hyperparathyroidism?

Answer 5

T4, T3 high
TSH low (primary) if overactive thyroid gland
TSH high (secondary) if pituitary issue (tumour)

Question 6

What is the main feature of sub-clinical thyroid disease?

Answer 6

abnormal TSH

normal FT4, FT3