Thyroid Gland Disorders

Question 2

what is Thyrotoxicosis?

Answer 2

Clinical, physiological and biochemical findings in response to elevated thyroid hormone

Irrespective of cause of elevation

Question 3

what is Hyperthyroidism?

Answer 3

Excess levels of thyroid hormone due to hyperfunctioning of thyroid gland

Question 4

what is Hypothyroidism?

Answer 4

Decreased levels of thyroid hormones

Question 5

what is Goiter?

Answer 5

Enlargement of thyroid gland

Question 6

what is Multinodular goiter (MNG):?

Answer 6

Enlarged thyroid with nodules in it.

Question 7

what is Toxic MNG?

Answer 7

One or more nodules in MNG producing thyroid hormone.

Question 8

what is Adenoma:?

Answer 8

Benign tumor of thyroid gland

Question 9

what is Toxic adenoma:?

Answer 9

Adenoma producing thyroid hormone

Question 10

what is Factitious thyrotoxicosis?

Answer 10

Hyperthyroidism due to exogenous administration of thyroid hormone.

Question 11

what are the thyroid hormones?

both are stored as what? where?

Answer 11

Triiodothyronine (T3) and

Thyroxine (T4)

colloid in the thyroid follicle

Question 12

when thyroid hormones are released into the circulation, they are present in two forms?

Answer 12

free and bound

Question 13

what happens to free T4?

what happens to free T3?

bound T4 and T3 are bound to what?

Answer 13

gets converted to T3

is metabolically active

to thyroid binding globulin

Question 14

what is the relationship between Free T4 and Free T3 and TSH?

Answer 14

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.

Question 15

what does Total serum T4 tell you?

Answer 15

Reflects hormone that is

• Bound to TBG and is
• Free or metabolically active

Question 16

What causes an increase in total T4 via free T4?

and via TBG?

Answer 16

• Increase in free T4 (Pri.hyperthyroidism)
• Increase in TBG (estrogen)

Question 17

Decrease in total T4, via free T4 is caused by* what?

and via TBG?

Answer 17

• Decrease in free T4 (Pri.hypothyroidism)
• Decrease in TBG (anabolic steroids)

Question 18

what is the best overall screen test for thyroid dysfunction?

Answer 18

serum TSH

Question 19

what do you look for in the TSH in hyperthyroidism?

Answer 19

• Primary: TSH low (negative feedback from increased T3/T4)
• Factitious thyrotoxicosis: TSH low
• Secondary: increased TSH (causes increased T3/T4)

Question 20

what do you look for in the TSH in hypothyroidism?

Answer 20

• Primary: increased TSH, less negative feedback from T3/T4
• Secondary: TSH is low

Question 21

tsh looks like what other hormone?

Answer 21

hcg

Question 22

what does radioactive iodide measure?

Answer 22

Evaluates thyroid gland synthetic activity.

because: Iodide is used to synthesize thyroid hormone.

Question 23

Increased I 131 uptake indicates what?

example?

Answer 23

increased synthesis of T4

Grave’s disease, toxic nodular goiter

Question 24

Decreased I 131 uptake indicates?

examples?

Answer 24

Inactivity of thyroid gland

• Patient taking thyroid hormone.
• Primary hypothyroidism

Question 25

if there is decreased uptake in a nodule with I 131 what can you assess?

examples?

what should be the normal?

Answer 25

• Cold nodules: inactive, do not take up I131
• Example: Cysts , cancers of thyroid
• Normally functioning gland takes up I 131

Question 26

if there is increased uptake in a nodule with I 131 what can you assess?

examples?

what should be the normal?

Answer 26

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

Question 27

what are the Thyroid autoantibodies that will be increased in Hashimoto’s Thyroiditis?

Answer 27

Thyroglobulin antibodies, thyroid peroxidase antibody, TSH receptor inhibiting antibodies

Question 28

what are the thyroid autoantibodies that are Increased in Graves disease?

Answer 28

Thyroid stimulating immunoglobulin (TSI)

Question 29

how is a Thyroid biopsy done?

what will it show?

Answer 29

Fine needle aspiration cytology (FNAC)

• Differentiates between benign and malignant disease