Thyroid Disorders

Question 1

The thyroid functions to…

Answer 1

1) produce thyroid hormones
2) regulate metabolism (cardiac and nervous system functions, body temperature, muscle strength, skin dryness, menstrual cycles, weight and cholesterol)

Question 2

Two thyroid hormones produced by the thyroid gland are…

Answer 2

1) triiodothyronine (T3)

2) thyroxine (T4)

Question 3

The thyroid gland is the only organ that can…

Answer 3

absorb iodine, which is required for the production of both hormones

Question 4

Thyroid-stimulating hormone (TSH) produced by the pituitary gland stimulates the secretion of…

Answer 4

T3 and T4

Question 5

T3 is primarily formed from…

Answer 5

the breakdown of T4. A small percentage (<20%) is made by the thyroid gland directly. T3 is more potent, but has a shorter half-life

Question 6

Free T4 (FT4) is the unbound, active form that is…

Answer 6

monitored in patients with thyroid disorders

Question 7

Feedback loops are used to regulate production. When the level of free T4 increases, this…

Answer 7

inhibits the secretion of TSH. Less TSH will lead to a decrease in T4.

Question 8

Hypothyroidism is characterized by…

Answer 8

a deficiency in T4, and consequently, an increase in TSH

Question 9

Hypothyroidism is most common in women (~80% of cases) and with increased age. The most common cause is…

Answer 9

Hashimoto’s disease, an autoimmune condition in which a patient’s own antibodies attack the thyroid gland

Question 10

A diagnosis of hypothyroidism is made using 2 lab test results:

Answer 10

1) Low free T4: normal range 0.9-2.3 ng/dL
2) High TSH: normal range 0.3-3 mIU/L
Consider screening in patients> 60 y/o

Question 11

Myxedema coma is a rare, but potentially fatal complication of hypothyroidism. It is a life-threatening emergency characterized by poor circulation, hypothermia, and hypometabolism. Initial treatment is…

Answer 11

IV levothyroxine

Question 12

Major symptoms of hypothyroidism include…

Answer 12

Code intolerance, dry skin, fatigue, constipation, weight gain, voice changes, weakness, depression, menorrhagia (heavy period)

Question 13

Drugs that can cause hypothyroidism “I TALC”:

Answer 13

Interferons

Tyrosine kinase inhibitors
Amiodarone (contains iodine)
Lithium
Carbamazepine

Question 14

TSH is primarily tested to monitor hypothyroidism.

Answer 14

The TSH level and symptoms should be monitored every 4-6 weeks until levels are normal, then 4-6 months later, then yearly.

Question 15

Too high of a dose in the elderly can cause…

Answer 15

hyperthyroidism (afib and fractures)

Question 16

Serum FT4 is monitored in addition to TSH in…

Answer 16

1) central hypothyroidism (rare), which is a defect in pituitary production of TSH
2) when treating pregnant women

Question 17

The drug of choice for the treatment of hypothyroidism is…

Answer 17

levothyroxine (T4). Brands: Synthroid, Levoxyl, Unithroid, Euthyrox, Tirosint, Tirosing-SOL). Keep consistent formulation and manufacturer to minimize variability.

Question 18

Levothyroxine counseling points:

Answer 18

1) Take 60 minutes before breakfast, on an empty stomach (with water only)
2) Can take at bedtime (at least 3 hours after last meall)

Question 19

Non-preferred treatments include:

Answer 19

1) desiccated thyroid (T3 and T4) (Armour Thyroid, Nature-Throid, NP Thyroid, Westhroid, WP Thyroid)
2) liothyronine (T3); Cytomel, Triostat

Question 20

The full replacement dose of levothyroxine is…

Answer 20

1.6 mcg/kg (IBW)/day. Start with full dose in otherwise healthy, young (<50 years of age) patients. Start with a lower dose in milder hypothyroidism and those with comorbidities. Elderly often need 20-25% less/kg; may require <1 mcg/kg/day. If known CAD, start with 12.5-25 mcg daily.

Question 21

Levothyroxine IV:PO conversion

Answer 21

0.75:1 (can vary by institution). Use IV immediately upon reconstitution.

Question 22

Drugs that decrease levothyroxine absorption and should be spaced by 4 hours include:

Answer 22

1) Antacids and polyvalent cations containing Fe, Ca, Al, or Mg
2) Multivitamins (containing ADEK, folate, iron)
3) Cholestyramine
4) Orlistat (Xenical, Alli)
5) Sevelamer
6) Sucralfate

Question 23

Drugs that decreased thyroid hormone levels include:

Answer 23

1) Estrogens
2) SSRIs
3) Liver inducers

Question 24

Thyroid hormone replacement can change the [ ] or effect of these drugs..

Answer 24

1) increased effect of warfarin (PT/INR)

2) decreased levels of theophylline

Question 25

Levothyroxine colors: Orangutans Will Vomit On You Right Before They Become Large, Proud Giants

Answer 25

``` 25 mcg: orange 50 mcg: white 75 mcg: violet 88 mcg: olive 100 mcg: yellow 112 mcg: rose 125 mcg: brown 137 mcg: turquoise 150 mcg: blue 175 mcg: lilac 200 mcg: pink 300 mcg: green ```

Question 26

Hyperthyroidism occurs when there is...

Answer 26

an overproduction of thyroid hormones. Free T4 (FT4) is high, TSH is low.

Question 27

Symptoms of hyperthyroidism include..

Answer 27

1) Faster metabolism 2) Weight loss 3) Agitation, nervousness 4) Heat intolerance 5) Tremor 6) Insomnia 7) Palpitations and tachycardia 8) Light or absent periods in women 9) Exophthalmos (bulging eyes)

Question 28

The most common cause of hyperthyroidism is...

Answer 28

Graves' disease, which most commonly occurs in females aged 30-50 years. Also an autoimmune condition (antibodies stimulate the thyroid to make too much T4)

Question 29

Drug-induced causes of hyperthyroidism include:

Answer 29

iodine (from diet or radiographic contrast media), amiodarone, interferons, too much levothyroxine

Question 30

Treatment for hyperthyroidism can include:

Answer 30

1) destroying a part of the gland using radioactive iodine (RAI-131) 2) thyroidectomy surgery 3) Anti-thyroid medications (PTU, methimazole) 4) Beta-blockers for symptom control 5) Temporary effect from KI (Lugol's solution) or saturated solution of KI (SSKI)

Question 31

To control symptoms, anti-thyroid medications need to be taken for...

Answer 31

at least 1-3 months at high doses. Once symptoms are controlled, the dose should be decreased to prevent hypothyroidism from occurring.

Question 32

Radioactive iodine can increase the risk of thyroid cancer. Potassium iodide...

Answer 32

blocks the accumulation of radioactive iodine in the thyroid gland and should be taken ASAP after radiation exposure. Check dosing on CDC website.

Question 33

Thyroid storm is a life-threatening medical emergency characterized by decompensated hyperthyroidism. Can be precipitated by...

Answer 33

infection, trauma, surgery, radioactive iodine treatment or non-adherence to anti-thyroid medication.

Question 34

Signs and symptoms of thyroid storm are...

Answer 34

fever (>103°F), tachycardia, tachypnea, dehydration, profuse sweating, agitation, delirium, psychosis, comg

Question 35

Drug treatment for thyroid storm includes...

Answer 35

1) Anti-thyroid drug therapy (PTU is preferred); give ≥ 1 hour before iodide 2) Inorganic iodide therapy such as SSKI or Lugol's + 3) Beta-blocker + 4) Systemic steroid + 5) Supportive treatment (cooling, fluids, etc)

Question 36

Untreated maternal hypothyroidism has been associated with...

Answer 36

loss of pregnancy, low birth weight, premature birth and lower IQ in children

Question 37

Levothyroxine is safe in pregnancy and is first-line for hypothyroidism. Ideally, start it before pregnancy. Pregnant women will require a...

Answer 37

30-50% increase in the dose throughout the course of their pregnancy and for several month after giving birth

Question 38

Poor control of hyperthyroidism in pregnancy is associated with...

Answer 38

pregnancy loss, prematurity and low birth weight, thyroid storm, maternal HTN, and congestive HF. Lasting effects in baby can include seizures and neurobehavioral disorders.

Question 39

Pregnancy should be postponed until..

Answer 39

a stable euthyroid state is reached. If a woman with hyperthyroidism becomes pregnant, she should be evaluated to see if tx can be stopped (mild disease). If treatment is needed, start anti-thyroid drugs based on the trimester

Question 40

In pregnant women, the preferred drug during the first trimester is..

Answer 40

PTU (due to fetal toxicity with methimazole). Switch to methimazole in the 2nd and 3rd (due to lower risk of liver toxicity)

Question 41

Propylthiouracil (PTU) and methimazole

Answer 41

BBW for PTU: severe liver injury and acute liver failure Warnings: liver toxicity, bone marrow suppression (rare, includes agranulocytosis), DILE, vasculitis Note: Take with food to reduce GI upset

Question 42

Methimazole is the drug of choice due to...

Answer 42

lower risk of liver damage (except in thyroid storm and 1st trimester of pregnancy)

Question 43

Monitoring for PTU and methimazole

Answer 43

Free T4 and T3 Q 4-6 weeks until euthyroid, TSH, CBC, LFTs and PT

Question 44

Monitoring for PTU and methimazole

Answer 44

Free T4 and T3 Q 4-6 weeks until euthyroid, TSH, CBC, LFTs and PT. Patient must monitor for liver toxicity (abdominal pain, yellow skin/eyes, dark urine, nausea, weakness) and infection (high fever or severe sore throat)

Question 45

JH is a 79-year-old female with HF and a history of MI. She is 5 feet tall and weighs 103 lbs. JH has just been diagnosed with hypothyroidism and is going to begin levothyroxine therapy. What is an appropriate dose?

Answer 45

25 mcg/day

Question 46

A pharmacist is counseling a patient on a new medication. He tells the patient to notify her healthcare provider if she experiences a group of symptoms together, such as muscle pain, weight loss, a butterfly rash on the face, and sunburn after sun exposure. Which medication is being dispensed?

Answer 46

Methimazole and/or PTU can cause DILE

Question 47

Which of the following drugs can cause hyperthyroidism?

Answer 47

iodine, amiodarone, interferon

Question 48

Which best describes the MOA of methimazole?

Answer 48

Inhibits thyroid gland synthesis of T4 by blocking the oxidation of iodine in the thyroid gland

Question 49

A medical resident asks the pharmacist for information on "desiccated thyroid" as he has heard that it is a more naturally-derived product than other treatment options. The pharmacist can tell him that it...

Answer 49

contains T3 and T4. It is not a first-line treatment for hypothyroidism, due to less predictable and variable responses, but some patients feel better using it than other products.