Thyroid Studies

Question 1

TSH

Answer 1

responsible for the synthesis and secretion of T3 (triiotathyronine) /T4 (thyroxine) -best screening test for thyroid function

Question 2

T3 and T4 function

Answer 2

assist with cellular respiration and metabolism

Question 3

TRH

Answer 3

thyrotropine releasing hormone (comes from hypothalamus)

Question 4

Thyroid feedback systems are present in the

Answer 4

hypothalamus and anterior pituitary

Question 5

TSH screening test normal value

Answer 5

normal 0.5-5.5 mlU/L -taken in red or marble top -not useful if they have had surgery on or damage to the anterior pituitary

Question 6

interfering factors in the TSH screening

Answer 6

radioisotope administration severe illness drugs

Question 7

increased TSH because of drugs could be

Answer 7

lithium

potassium iodide

TSH injection

Question 8

decreased TSH because of drugs could be

Answer 8

ASA

NSAIDS

heparin

corticosteroids (Prednesone in the case of RA)

Question 9

Thyroxine (T4)

Answer 9

More abundant thyroid hormone

Question 10

Triiodothryonine (T3)

Answer 10

thyroid hormone that is secreted in lesser amounts, but that is more metabolically active

-is T4 less one iodine

Question 11

Thyroid binding globulin (TBG)

Answer 11

protein that binds to T3/T4

• free T4 and T3 is what actually does the work
• produced in the liver
• free hormone levels are not altered by changes in TBG (stays constant)
• changes in TBG may affect total thyroid hormone levels

Question 12

free T4 test

Answer 12

2nd test that you would order in a thyroid work-up

Question 13

increase in TBG might be because of

Answer 13

high estrogen states (OCP, pregnancy, hormone replacement therapy)-gives total T4 elevation

infectious hepatitis (causes inflammation and churns out extra hormone)

genetic TBG excess

Question 14

decrease in TBG might be because of

Answer 14

liver disease (cirrhosis)

malnutrition

protein losing nephropathy

androgens

estrogen deficiency

major stress

Question 15

thyroid screening tests

Answer 15

1. TSH
2. Free T4

***Need to pay attention to whether it says FREE otherwise assume it is total

Question 16

thyroglobulin work up

Answer 16

indicated for someone who has a thyroid tumor

used as a tumor marker

• protein that is made by the thyroid gland
• elevated levels indicate residual thyroid tissue

Question 17

increased TSH level indicates

Answer 17

hypothyroidism

-thyroid is not responding to the TSH and pituitary is compensating by making more

>5.5 mgU/dl

Question 18

decreased TSH level indicates

Answer 18

hyperthyroidism

• pituitary is reading that thyroid hormone levels are high and decreases secretion of TSH
• <0.5 mgU/dl

Question 19

Two tests that are used to diagnose autoimmune disease

Answer 19

1. thyroid stimulating immunoglobulin (Graves dx)
2. thyroid antibodies (Hashimotos)
   - anti-TPO antibodies-most sensitive
   - antithyroglobulin antibodies-less sensitive