Investigation of Thyroid

Question 1

How do we measure hormones in blood?

Answer 1

Immunoassay

Question 2

What are the different types of Immunoassay?

Answer 2

Competitive immunoassay
immunometric assay

Question 3

What does a competitive imunoassay use?

Answer 3

A limited amount of antibody and is used for small molecules such as thyroid hormones or steroid hormones

Question 4

How does a competitive immunoassay work?

Answer 4

Add a limited amount of antibody and the sample and incubate. These will then try to competitevely bind to the receptor. You then wash out whatever is not bound.

The bound lable is inversely proportionate to analyte concentration - the more T4 in the sample the more it will outcompete and the lower the signal.

Question 5

immunometric assay

Answer 5

uses antibody excess and used for large peptides such as peptide hormones or proteins.

Question 6

in an immunometric assay what is used to increase specificity?

Answer 6

monoclonal antibodies

Question 7

How deos an immunometric immunoassay work?

Answer 7

You need the capture antibody bound to the side of the test tube. This antibody can bind to the analyte.

Another antibody (labelled antibody) can then bind to the other side of the analyte - this will only bind to samples.

The higher the analyte the more signal

Question 8

what are the possible ways the immunoassay can be configured?

Answer 8

Capture antibody - beads, magenetics, plastics, microlitre plate, fibre strip

Label antibody - radiolable, chemiluminescent, flourescence, enzyme linked,

Question 9

Why would you use a thyroid function test?

Answer 9

Establish a thyroid dysfunction and monitor treatment

Question 10

What thyroid measurements would you want to test for?

Answer 10

TSH
free T4/T3

Hyperthyroidism specific = TSH Receptor Ab
Hypothyroidism specific = Anti-TPO Ab

Question 11

Should you measure both TSH and T4 together to get to the source of the problem?

Answer 11

Yes

Question 12

Hypothyroidism test what would you expect the biochemical tests to look like?

Answer 12

Low T4 and high TSH

Question 13

Hypopituitarism test what would you expect the biochemical tests to look like?

Answer 13

Low T4, normal or low TSH (the TSH is less active by loosing glycolysation)

Question 14

Biochemical test results of primary hypoparathyrodism?

Answer 14

High TSH
Low T4
Normal or low T3

Question 15

Biochemical test results of secondary hypothyroidism?

Answer 15

Low TSH or normal
Low T4
Low of normal T3

Question 16

Hypethyroidism test what would you expect the biochemical tests to look like?

Answer 16

High TSH
High FT4 and FT3

Question 17

biochemical test results primary hyperthyroidism?

Answer 17

Low TSH
High T4 and T3

Question 18

Biochemical test results for secondary hyperthyroidism? This is rare

Answer 18

High or normal TSH
High T4 and T3

Question 19

What is more senstive TSH or T4?

Answer 19

TSH for every 4x increase in T4 TSH drops by 10x

Question 20

What would the biochemical results be for someone who is sub clincal hyperthyroidism?

Answer 20

T4 high for you but “normal” as it is in the range but TSH is switched of?

T3 normal

Question 21

What would the biochemical results be for someone who is sub clincal hyporthyroidism?

Answer 21

Normal T4 and T3 but low TSH

Question 22

How would you know if the sub clinical disease is trying to become over disease such as graves?

Answer 22

Thyroid antibodies

Question 23

what is panhypopituitarism?

Answer 23

when your pituatiry gland is not right

Question 24

What is Non-thyroidal illness

Answer 24

Intercurrent illness can affect functioning of pituirary thyroid axis

Can lead to difficulty interpreting the results of thyroid functional tests.

Question 25

Can acute illness - pneumonia upset the TSh and T4 levels?

Answer 25

Yes

Question 26

What can cause reduced TSH?

Answer 26

Malnutrician, illness or stress

Question 27

What can stress, illness and malnutrician do to deoidinase type 2?

Answer 27

Reduce this increasing production of rT3 which means you can’t treat these people with T4 as it will just turn into rT3

Question 28

In acute hospital setting what would a low TSH probably be?

Answer 28

Twice as likely to be a non-thyroidal illness as hyperthyroidism

Question 29

In acute hospital setting what would a raised TSH probably be?

Answer 29

As likely to be due to recovary from illness as hypothyroidism

Question 30

What must TFTs be interpreted alongside?

Answer 30

interpreted alongside clinical findings