20 Questions
Which of the following is true regarding primary hypothyroidism?
Plasma [TSH] increases
What is a characteristic feature of secondary or tertiary hypothyroidism?
TSH,T4, and T3 are all decreased
Which statement is true about medications that interfere with thyroid function testing?
Biotin can interfere with measurement of thyroid hormones in the lab
What is the purpose of determining the presence of autoimmune thyroid diseases such as Graves’ disease or Hashimoto’s thyroiditis?
To establish the presence of elevated thyroid antibodies despite normal TSH
What is a characteristic feature of primary hyperthyroidism?
Plasma free and total T4 and T3 levels are increased
Which test is often considered the diagnostic 'gold standard' for thyroid disease?
Thyroid Stimulating Hormone (TSH) test
What is the effect of increased TBG level on the concentrations of total T4 and T3?
It increases the concentrations of total T4 and T3
Which test provides a more reliable diagnosis of thyroid dysfunction than measurement of total T4 and T3?
Free T3 and T4 test
In primary hyperthyroidism, what are the levels of T4, T3, and TSH due to feedback inhibition?
$T4$ and $T3$ are increased, $TSH$ is decreased
What is the effect of a normal TSH level on some patients with ongoing symptoms?
It does not exclude the possibility of thyroid disease
In primary hypothyroidism, both T4 and T3 levels are decreased, and TSH levels are increased.
True
Elevated thyroid antibodies always indicate the presence of autoimmune thyroid diseases such as Graves’ disease or Hashimoto’s thyroiditis, despite a 'normal' TSH level.
False
Secondary hypothyroidism is characterized by decreased levels of TSH, T4, and T3.
True
Primary hyperthyroidism is characterized by decreased plasma TSH levels due to feedback inhibition on the pituitary.
False
Estrogens, such as those found in birth control pills, can cause high levels of total T4 and T3 due to their effect on binding proteins.
True
TSH level in the blood is not a reliable test for thyroid status for all patients with ongoing symptoms.
True
Total T4 and total T3 are more reliable for diagnosing thyroid dysfunction than free T3 and T4.
False
Changes in TBG level do not affect the concentrations of total T4 and total T3 in plasma.
False
Thyroid antibody tests are used to determine the presence of autoimmune thyroid diseases such as Graves’ disease or Hashimoto’s thyroiditis.
True
In primary hyperthyroidism, both T4 and T3 levels are decreased, and TSH level is increased due to feedback inhibition.
False
Test your knowledge of thyroid function tests and the hypothalamic-pituitary-thyroid axis, including the negative feedback mechanism. Explore laboratory blood tests such as TSH level and thyroid function tests like T4, T3, thyroglobulin, and thyroid antibody tests.
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