Hypothyroidism TBL

Question 1

What factors cause high risk for hypothyroidism?

Answer 1

History of autoimmune disease, history of head or neck radiation, previous radioactive iodine therapy, goiter, family history, known interacting drugs

Question 2

List the symptoms associated with hypothyroidism

Answer 2

Cold intolerance, fatigue, constipation, dry skin, muscle weakness, hair thinning/hair loss, irregular menstruation, infertility, goiter

Question 3

Under what circumstances should you screen a patient for hypothyroidism?

Answer 3

If they have any factors that classify them as high-risk, or if they are having hypothyroid symptoms

Question 4

Which tests should be ordered for a hypothyroid screen?

Answer 4

A TSH level, and if elevated, free T4 level

Question 5

What would labs show in a patient with primary hypothyroidism?

Answer 5

Elevated TSH (greater than 5 mIU/L), with low serum free T4 (less than 0.8 mIU/L),

Question 6

List the etiologies of hypothyroidism

Answer 6

Can be primary, secondary, or tertiary. Primary can result from congenital disorders, autoimmune destruction, iodine deficiency, infiltrative diseases, iatrogenic (post surgery or radiation, medication interaction)

Question 7

What drug and dose would be first used for a typical hypothyroid patient?

Answer 7

Levothyroxine (1.6 mcg/kg/day)

Question 8

How does levothyroxine dosing change for pregnant patients?

Answer 8

Nine doses per week are recommended

Question 9

How does levothyroxine dosing change in a patient with ischemic heart disease?

Answer 9

Start at 25 mcg or 50 mcg daily, increasing by 25 mcg every month until full dose is reached

Question 10

List medications that can interfere with levothyroxine

Answer 10

Calcium and iron supplements (within four hours of taking levothyroxine), cholestyramine, colestipol, orlistat, sucralfate, carbamazepine, sertraline

Question 11

List for medications that can contribute to thyroid dysfunction

Answer 11

Lithium, amiodarone, interleukin-2, tyrosine kinase inhibitors

Question 12

What is myxedema coma?

Answer 12

A severe manifestation of hypothyroidism involving lethargy, cognitive dysfunction, psychosis, and hypothermia. Can also cause hyponatremia, hypoventilation, and bradycardia

Question 13

What are risk factors for myxedema coma?

Answer 13

Older women with a history of primary hypothyroidism

Question 14

When would you refer a patient with suspected hypothyroidism to endocrinology?

Answer 14

Younger than 18, cardiac disease, myxedema coma, pregnancy, goiter/nodule, unresponsive to therapy