Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Gabe's Endocrinology > Hormone Measurement and Interpretation > Flashcards

Hormone Measurement and Interpretation Flashcards

1
Q

Why measure hormones?

A
  • Confirm clinical suspicion
  • Diagnose sub-clinical problems
  • Assess Treatment
  • Time Procedures (IVF)
  • Screening (e.g. neonatal hypothyroidism)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a patient complaining of weight gain and fatigue with a low free thyroxine level likely to have?

A

Hypothyroidism due to thyroid dysfunction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What levels of free thyroxine and TSH would be consistent with hypothyroidism due to thyroid dysfunction?

A

Low free thyroxine and high TSH.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What levels of free thyroxine and TSH would be consistent with hypothyroidism due to pituitary dysfunction?

A

Low free thyroxine and low TSH.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the expected TSH and thyroxine levels in overactive thyroid?

A
  • Low TSH
  • High Thyroxine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the expected TSH and thyroxine levels in underactive thyroid?

A
  • High TSH
  • Low Thyroxine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the expected TSH and thyroxine levels in pituitary underactivity?

A
  • Low TSH
  • Low Thyroxine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why is TSH a better screening test for thyroid disease?

A

Because TSH will move outside of the reference range before FT4.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What factors affect the test used?

A
  • Normal Homeostasis
  • Common causes of dysfunction
  • Availability of test
  • Reliability of test
  • Sensitivity, Specificty
  • Cost of test
  • Govt. regulation.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What can reference ranges vary with?

A
  • Age
  • Menstrual state
  • Sex
  • Medication
  • Race
  • Person
  • Nutritional state
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What do dynamic tests involve?

A
  • Sampling at multiple time points
  • May involve stimulating or suppressing the gland to see if it responds appropriately
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

When is dynamic testing useful?

A
  • Subclinical Disease
  • A diseased system may appear to function normally under basal conditions but show abnormalities if stressed.
  • Investigating Abnormal Results.
  • Is an abnormal hormone result due to a physiological or pathological cause?
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are some examples of dynamic endocrine tests?

A
  • Glucose Tolerance Test
  • Dexamethasone Suppression Test
  • Synacthen stimulation Test
  • Combined Pituitary Function Test
  • GH suppression Test
  • GH stimulation test
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the glucose tolerance test?

A

Fasting patient is given 75g of glucose at 0min and then specimens for glucose are taken at 0, 1 and 2 hours. See image.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What will the glucose level of a diabetes patient be after 2 hours into the glucose tolerance test?

A

High

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does the Dexamethasone Suppression Test test?

A
  • Adrenal gland function by measuring how cortisol levels change in response to an injection of dexamethasone.
  • Used to test for Cushing’s syndrome.
17
Q

What does an elevated cortisol level following the dexamethasone suppression test suggest?

A

Failure of suppression, evidence of Cushing’s syndrome.

18
Q

What does the Synacthen Stimulation Test test?

A
  • Adrenal underactivity.
  • Stimulate the gland with ACTH and measure cortisol levels.
19
Q

What is the Synacthen Stimulation Test?

A
  • 250µg Synacthen IM at time 0 min
  • Blood cortisol at 0, 30 and 60 min.
20
Q

What is the growth hormone stimulation test?

A
  • Cases where GH production is suspect
  • Stimulate GH release and see if increases.
  • Stimulus may be exercise, hypoglycaemia,
  • Arginine (arginine insulin test)
21
Q

What is the growth hormone suppression test?

A
  • Perform GTT with GH levels.
  • Elevated glucose should cause suppression of GH
  • Rarely used as now have good GH and ILGF-1 assays
22
Q

What are the two types of immunoassays for hormone measurement?

A
  • Competitive Immunoassays
  • Non-Competitive Immunoassays (Sandwich technique)
23
Q

What is a competitive immunoassay for hormone measurement?

A

Principle: competition between specimen hormone and added labelled hormone for limited amount of antibody.

  1. Add serum + labelled hormone to antibody.
  2. Incubate
  3. Remove non-bound labeled hormone
  4. Measurement of label
24
Q

What is a non-competitive sandwich immunoassay for hormone measurement?

A

Principle: antigen held between 2 antibodies, one of which is labelled. Improved specificity as 2 binding sites are used.

  • Add serum to antibody
  • Add labeled antibody
  • Incubate
  • Remove non-bound labeled antibody
  • Measure amount of signal
25
Q

What is the free hormone hypothesis?

A
  • The unbound hormone is the active form and what should be measured.
  • However, it’s difficult just to measure free hormone and not the bound hormone in the serum.
26
Q

What is the difference between using polyclonal and monoclonal antibodies?

A
  • Polyclonal: strong binding, may lack specificity.
  • Monoclonal: can be weak binding, good specificity.
27
Q

What are some of the problems with antibody specificity in immunoassays?

A

Antibody may cross-react with similar looking antigens, e.g. cortisol and other steroid hormones.

28
Q

What are some of the problems with standardisation in immunoassays?

A
  • Ideally the assay standards should be traceable back to an internationally referenced preparation of known constituents.
  • Different manufacturers may use different standards (and antibodies)
  • → Different results from different laboratories
29
Q

What are some of the problems with sample stability and quality in immunoassays?

A
  • Results are dependent on quality of sample, e.g, haemolysed, lipaemic samples
  • Some analytes are very temperature sensitive and need to be kept cold or frozen as soon as separated from blood
  • Some analytes require special tubes and/or special preservatives to prevent degradation
30
Q

What are some of the problems with patients with hormone autoantibody in immunoassays?

A
  • The patient has a naturally occurring autoantibody which binds to normal hormone.
  • This may effect:
  1. hormone half-life
  2. biological effects
  3. Response in immunoassays
  4. May have differing effects depending on type of assay used and how the antibody binds.
31
Q

What is the problem with patients with heterophilic antibodies in immunoassays?

A

The heterophilic antibody will bind the anti-mouse antibody to the capture antibody, giving a falsely high result.

Gabe's Endocrinology (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions