Thyroid Disorders

Question 1

Differentiate the thyroid hormones?

Answer 1

T3 triiodothyronine: more potent
T4 thyroxine: shorter half-life

Thyroid is the only hormone that can absorb iodine for TH

T4 broken down to T3 in the periphery

Question 2

Where is TSH secreted?

Answer 2

Pituitary gland

Question 3

What is the active form of thyroid hormone

Answer 3

Free T4 → monitored in disorders

Question 4

Drugs that cause hypothyroidism?

Answer 4

Interferons
TKIs
Amiodarone
Lithium
Carbamazepine

Question 5

What is hypothyroidism? Autoimmune disease?

Answer 5

Deficiency in T4 → elevations in TSH

Hashimoto’s

Question 6

Main complication of hypothyroidism? Treatment?

Answer 6

Myxedema coma → IV Levothyroxine

Question 7

SX of hypothyroidism?

Answer 7

Slow metabolism:

Cold intolerance
Dry skin
Fatigue
Cramps (muscle)
Voice change
Weight gain
Goiter (low iodine)
Weakness
Coarse hair
Heavier period
Memory impairment
Constipation

Question 8

How do you diagnose hypothyroidism

Answer 8

High TSH: >3
Low free T4: >2.3

Question 9

How often do you monitor for hypothyroidism?

Answer 9

Monitor TSH Q4-6W until normal → 4-6 months later → then yearly

Question 10

ADRs if thyroid replacement is too high?

Answer 10

A fib, fractures

Question 11

Drug of choice for hypothyroidism?

Answer 11

Levothyroxine (T4)

Question 12

Levothyroxine

Answer 12

T4: Synthroid, Levoxyl, Unithyroid

Question 13

Thyroid Desiccated

Answer 13

T3 and T4: ArmorThyroid, NP Thyroid

Question 14

Liothyronine

Answer 14

T3: Cytomel

Question 15

Full replacement dose of Levothyroxine?

Answer 15

1.6 mcg/kg/day (IBW) → healthy, long (<50YO), and markedly ↑ TSH

If know CAD, start with 12.5-25 mcg QD

Elderly: 20-25% less/kg: <1 mcg/kg/day

Question 16

Warning of Thyroid replacement

Answer 16

↓ dose CVD, lowers bone mineral density → osteoporosis

Question 17

ADR of thyroid replacement

Answer 17

Hyperthyroidism: ↑ HR, palpitations, sweating, weight loss, arrhythmias

Question 18

Counseling of Levothyroxine

Answer 18

Take with water 60 min before breakfast or at bedtime 3 hrs after eating

Question 19

Why is ArmorThyroid not recommended

Answer 19

Dosed in grains → variable amount of T4 and T3

Question 20

Levothyroxine IV to PO

Answer 20

0.75:1

Question 21

Levothyroxine tablets

Answer 21

Orange: 25 mcg
White: 50 mcg
Violet: 75 mcg
Olive: 88 mcg
Yellow: 100 mcg
Rose: 112 mcg
Brown: 125 mcg
Turquoise: 137 mcg
Blue: 150 mcg
Lilac: 175 mcg
Pink: 200 mcg
Green: 300 mcg

Orangutans will vomit on you right before they become large proud giants

Question 22

Drugs that ↓ levothyroxine absorption?

Answer 22

Antacids (iron, calcium, aluminum, mg or multivitamins)
Cholesteramine
Sevelamer
Sucralfate

Separate for 4 hrs from THR

Question 23

DI of TRH and SPS, Veltessa

Answer 23

Separate doses by 3 hrs from THR

Question 24

DI of TRH and Lanthanum

Answer 24

Separate doses by 2 hrs from THR

Question 25

THR interacting with other drug levels?

Answer 25

↑ warfarin ↓ theophylline

Question 26

Pregnancy dosing for hypothyroidism?

Answer 26

↑ levothyroxine by 30-50%

Question 27

What is hyperthyroidism?

Answer 27

Overactive thyroid FT4: high TSH: low

Question 28

Sx of hyperthyroidism?

Answer 28

Heat intolerance, sweating Weight loss Arrhythmias, palpitations, tachykardia Thinning hair Insomnia Exophthalmos Light menstruation Diarrhea Irritability

Question 29

Drugs that induce hyperthyroidism?

Answer 29

Iodine, amiodarone, interferons

Question 30

Treatment for hyperthyroidism

Answer 30

Drugs: PTU, Methimazole Radioactive iodine (RAI-131) Surgery

Question 31

How do you treat sx of hyperthroidism?

Answer 31

BB (reduce palpitations, tremors, tachycardia)

Question 32

How long does it take for hyperthyroidism treatment to reach full effect?

Answer 32

1-3 months at high doses to control sx - Doses should be reduce after symptomatic control to avoid hypothyroidism

Question 33

MOA of thionamides?

Answer 33

Inhibit synthesis of TH by blocking the oxidation of iodine in the thyroid glans PTU also inhibits peripheral conversion of T4 to T3

Question 34

BBW of antithyroid drugs

Answer 34

Severe liver injury and acute liver failure

Question 35

Warning and ADR of antithyroid?

Answer 35

Hepatotoxicity, agranulocytosis, DILE GI upset

Question 36

Antithyroid drug of choice

Answer 36

Methimazole 2nd and 3rd trimester

Question 37

When would PTU be drug of choice

Answer 37

Thyroid storm 1st trimester → decreased fetal abnormalities

Question 38

MOA of iodine

Answer 38

Temporarily inhibits secretion of TH, Reduction for weeks but not maintained

Question 39

Iodide products

Answer 39

Potassium iodide (Lugol's solution) Saturated solution of potassium iodide (SSKI)

Question 40

Dosing of Lugols

Answer 40

Throidectamy: 5-7 get Q8H for 10 days prior to surgury

Question 41

Dosing of SSKI

Answer 41

Thyroidectomy: 1-2 GTT Q8H for 10 days prior to surgery

Question 42

Purpose of potassium iodide after radiation?

Answer 42

Blocks the accumulation of radioactive iodine in thyroid gland → preventing thyroid cancer

Question 43

Crisis of hyperthyroidism?

Answer 43

Thyroid storm → decompensated thyroid due to infection, trauma, surgery, radioactive iodine, non-adherence to antithyroid

Question 44

Sx of thyroid storm

Answer 44

Fever >103 Tachycardia Tachypnea Dehyrdation Sweating Agitation Delirium Psychosis Coma

Question 45

Tx for thyroid storm

Answer 45

1. PTU: 500-1000 mg LD, then 250 mg Q4H 2. Inorganic iodide therapy: SSKI 5 gtt in water or juice PO Q6H or Lugol's 4-8 get PO Q6-8H 3. BB: propranolol 40-80 mg PO Q6H 4. Systemic steroid: dexamethasone 2-4 mg PO Q6H 5. Agressive cooling with APA and cooling blankets Antithyroid should be given ≥1 before iodide to block synthesis of TH