Lec 05: Diagnostic Tests in Thyroid Disorders Flashcards
T/F: Approximately 1 out of 10 Filipinos has abnormalities in their thyroid function tests (TFTs).
T
8.53%
T/F: Majority of the Filipinos with TFT abnormalities have subclinical thyroid disease.
T
Reasons for doing thyroid function tests EXCEPT
A. formulate a primary working impression
B. supplement physical exam findings
C. monitor clinical response to treatment
D. determine risk for malignancy
E. NOTA
A.
Formulation of primary working impression should be based primarily on history and PE.
ID: What is the only available function test in the 1950s?
indirect estimation of thyroxine (T4)
ID: What hormone establishes the set point in the regulation of the H-P-T axis?
TSH
ID: Probable diagnosis
↓ TSH, ↑ T4, ↑ RAIU
Graves’ disease
hyperfunctional multinodular goiter
hyperfunctional thyroid adenoma
True of iodide uptake
A. mediated by sodium-iodide symporter (NIS)
B. occurs at the basolateral membrane
C. extracts normally around 10-25% of serum iodide
D. A & B only
E. AOTA
E. AOTA
ID: What transports iodide from the thyrocyte to the follicular lumen?
pendrin
ID: This protein receptor mediates endoyctosis of thyroglobulin back into the thyrocyte.
megalin
True of TSH EXCEPT
A. first line test in most clinical setting
B. may be sufficient to diagnose a patient
C. exhibits log-linear relationship with T4
D. controls the H-P-T axis
E. NOTA
B.
TSH is not enough to diagnose a patient. FT4 / FT3 must also be tested.
T/F: A linear fall in FT4 produces a linear increase in TSH.
F
It results in LOGARITHMIC increase in TSH. (log-linear relationship)
ID: When does TSH peak in a normal ambulatory patient?
between midnight to 4:00 am
True of TSH testing
A. single determination is usually adequate
B. half-life is around 20 minutes
C. good specificity for detecting TSH secreting tumor
D. A & B only
E. AOTA
A.
Modest excursions, low variations in levels, and long half-life (50 mins) renders a single TSH test adequate.
What is the concern in TSH testing in hospitalized patients?
Non-thyroid illnesses / co-morbidities may alter lab results.
The following drugs increase TBG levels EXCEPT
A. estrogens B. 5-fluorouracil C. nicotinic acid D. glucocorticoids E. NOTA
D.
The following drugs decrease TBG
- thyroid hormones
- androgens
- anabolic steroids
- glucocorticoids
- L-asparaginase
- interleukin-6