Thyroid Gland Disorders Flashcards
what is Thyrotoxicosis?
Clinical, physiological and biochemical findings in response to elevated thyroid hormone
Irrespective of cause of elevation
what is Hyperthyroidism?
Excess levels of thyroid hormone due to hyperfunctioning of thyroid gland
what is Hypothyroidism?
Decreased levels of thyroid hormones
what is Goiter?
Enlargement of thyroid gland
what is Multinodular goiter (MNG):?
Enlarged thyroid with nodules in it.
what is Toxic MNG?
One or more nodules in MNG producing thyroid hormone.
what is Adenoma:?
Benign tumor of thyroid gland
what is Toxic adenoma:?
Adenoma producing thyroid hormone
what is Factitious thyrotoxicosis?
Hyperthyroidism due to exogenous administration of thyroid hormone.
what are the thyroid hormones?
both are stored as what? where?
Triiodothyronine (T3) and
Thyroxine (T4)
colloid in the thyroid follicle
when thyroid hormones are released into the circulation, they are present in two forms?
free and bound
what happens to free T4?
what happens to free T3?
bound T4 and T3 are bound to what?
gets converted to T3
is metabolically active
to thyroid binding globulin
what is the relationship between Free T4 and Free T3 and TSH?
Free T4 and Free T3 have negative relationship with TSH
An increase in FT4/FT3 should produce a decrease in TSH
A decrease in FT4/FT3 should produce an increase in TSH.
what does Total serum T4 tell you?
Reflects hormone that is
- Bound to TBG and is
- Free or metabolically active
What causes an increase in total T4 via free T4?
and via TBG?
- Increase in free T4 (Pri.hyperthyroidism)
- Increase in TBG (estrogen)
Decrease in total T4, via free T4 is caused by* what?
and via TBG?
- Decrease in free T4 (Pri.hypothyroidism)
- Decrease in TBG (anabolic steroids)
what is the best overall screen test for thyroid dysfunction?
serum TSH
what do you look for in the TSH in hyperthyroidism?
- Primary: TSH low (negative feedback from increased T3/T4)
- Factitious thyrotoxicosis: TSH low
- Secondary: increased TSH (causes increased T3/T4)
what do you look for in the TSH in hypothyroidism?
- Primary: increased TSH, less negative feedback from T3/T4
- Secondary: TSH is low
tsh looks like what other hormone?
hcg
what does radioactive iodide measure?
Evaluates thyroid gland synthetic activity.
because: Iodide is used to synthesize thyroid hormone.
Increased I 131 uptake indicates what?
example?
increased synthesis of T4
Grave’s disease, toxic nodular goiter
Decreased I 131 uptake indicates?
examples?
Inactivity of thyroid gland
- Patient taking thyroid hormone.
- Primary hypothyroidism
if there is decreased uptake in a nodule with I 131 what can you assess?
examples?
what should be the normal?
- Cold nodules: inactive, do not take up I131
- Example: Cysts , cancers of thyroid
- Normally functioning gland takes up I 131
if there is increased uptake in a nodule with I 131 what can you assess?
examples?
what should be the normal?
Increased uptake in a nodule:Hot nodules: functionally active,take up I131
Example: toxic nodular goiter
remainder of gland not seen, since it is suppressed
what are the Thyroid autoantibodies that will be increased in Hashimoto’s Thyroiditis?
Thyroglobulin antibodies, thyroid peroxidase antibody, TSH receptor inhibiting antibodies
what are the thyroid autoantibodies that are Increased in Graves disease?
Thyroid stimulating immunoglobulin (TSI)
how is a Thyroid biopsy done?
what will it show?
Fine needle aspiration cytology (FNAC)
- Differentiates between benign and malignant disease
