Exam 1 DPT V (Bragg)

What are the primary associated diseases causing hypothyroidism?

Hashimoto's disease

Iatrogenic

Iodide deficiency

Enzyme defects

Thyroid hypoplasia

What are the secondary causes of hypothyroidism?

Pituitary and Hypothalamic Disease

Signs and Symptoms of HYPOthyroidism

fatigue, cold intolerance, insomnia, weakness, bradycardia, coarse hair, dry skin, depression

TSH is reasonable to measure to rule out other diseases

Overt Primary Hypothyroidism

TSH > 4.5 and LOW free T4+ symptoms

Subclinical Primary Hypothyroidism

TSH > 4.5 and normal free T4

Secondary and Tertiary Hypothyroidism

impaired TSH response to TRH

low, normal or high TSH

can have other symptoms such as amenorrhea, galactorrhea, or ED

Hypothyroidism in Pregnancy Diagnosis

use similar TSH cutoffs, but prefer TOTAL T4 and diagnose if > 1.5 x upper limit reference range

Euthyroid-Sick Syndrome (Non-thyroidal illness)

altered thyroid function tests with critical illness and stress

TSH is lower than normal with a low or normal T3 and T4

TFTs don't make sense with negative feedback!!!

Treating Subclinical Hypothyroidism

< 65 years old

TSH > 10

Pregnant

Dosing: 25-75 mcg/day or 1 mcg/kg/day (based on IBW)

Overt Disease significant deficiency dosing (ablation, thyroidectomy)

1.6 mcg/kg/day (IBW)

Overt Disease in healthy older adults > 60 years old Dosing

25-50 mcg/day

Overt Disease patients with cardiac complications Dosing

12.5-50 mcg/day

Overt Disease Dosing in newly pregnant patients

increase dose 20-30% (2 additional tabs/week)

What is the drug of choice for thyroid supplementation?

levothyroxine (T4)

low cost, consistent potency

Why is Liothyronine (T3) avoided?

twice daily dosing and higher concern for CV risks

What is considered to be higher dosing of levothyroxine?

more than 200 mcg per day

What are reasons to give higher levothyroxine doses?

malabsorption conditions (Gastritis, Celiac disease, BMI > 40, > 70 years old, gastric bypass)

medication NONadherence

Drug interactions (Ca, iron, phenytoin, or PPIs)

What drugs decrease oral absorption of levothyroxine by binding with levothyroxine in the GI tract ?

acid suppression

di- and tri-valent cations (Ca, iron, Al)

cholestyramine

What drugs increase metabolism of levothyroxine reducing its effectiveness in hypothyroidism?

rifampin, phenytoin, carbamazepine

What drugs block the conversion of T4 to T3?

amiodarone

propylthiouracil

propranolol

corticosteroids

Administration of hypothyroid drugs

in the morning on an empty stomach 30-60 minutes before food vs at bedtime

Monitoring for hypothyroidism

TSH at 4-6 weeks (8 weeks if older) after starting and changing doses, then annually

TSH Goals of Subclinical Hypothyroidism

unclear, no benefit in treating adults > 65 years

potential mortality benefits if treating < 65 years young

Overt Hypothyroidism TSH goals

0.5 to 2.5 in younger patients

4-6 in adults in > 70 years

What TSH goal would be appropriate for healthy young or cardiovascular person?

2.5-4

What TSH goal would be appropriate for a pregnant female?

1.0-2.5

What drug should be held the week of the ablation as it may reduce the ablation effectiveness?

Methimazole

What drug can induce agranulocytosis?

methimazole

Signs and symptoms of Myxedema Coma

hypothermia, stupor, confusion, and skin and soft tissue swelling

Treatment for Myxedema Coma

T4 IV 200-400 mcg ONCE then IV vs PO 50-100 mcg/day

hydrocortisone IV 100 mg every 8 hours

If there is a concern with peripheral conversion with myxedema coma, what could be optional therapy?

T3 IV 5-20 mcg ONCE, then IV 2.5-10 mcg every 8 hours until improving and able to transition to levothyroxine alone

consider lower T4 doses if doing T3

What are some causes of hyperthyroidism?

Grave's Disease

Multinodular goiter

TSH secreting tumors

Gestational

Thyroiditis

Drug Induced

Food

What drug can induce hyperthyroidism?

amiodarone

What is a key sign that a patient has Grave's Disease?

strongly positive Trabs

Presentation of Hyperthyroidism

nervousness, anxiety, HEAT intolerance, hypertension, AFib, warm, moist skin, fine hair

irregular menses, infertility, goiter, weight LOSS, increased appetite, anorexia

Subclinical Hyperthyroidism Diagnosis

low or undetectable TSH and normal T3 and T4

Overt Hyperthyroidism Diagnosis

low or undetectable TSH and elevated T3 or T4

Hyperthyroidism diagnosis during pregnancy

Low TSH and total T3 and T4 1.5 x nonpregnant range

If your patient has low TSH, but > .10, what may this indicate in terms of their hyperthyroidism?

non-thyroidal illness or drug induced case

What lab interferes with lab assays and may cause false highs or lows of T4 and T3 as well as TSH?

biotin (vitamin B7)

If the patient has a non-urgent test, how long should you hold biotin for?

3 days

If your patient has an urgent test matter and is on biotin, what should you do before you test?

call the manufacturer

Complications from Thyrotoxicosis

AFib

Goiter

Proptosis (exophthalmos)

Osteroporesis and fracture

Maternal and fetal complications

Thyroid storm

MOA of anti-thyroid drugs

inhibit biosynthesis of thyroid hormone by blocking organification of iodines

Methimazole (MMI) Starting Dose

15-60 mg/day in 2-3 divided doses

What should you do in terms of tapering Methimazole?

taper monthly by 1/3 to a maintenance of 5-15 mg/day (dosed 1-2 times daily)

What is the maintenance dose of methimazole?

5-15 mg/day (1-2 times daily)

When should you see clinical improvement using Methimazole?

4-8 weeks

What is the drug of choice for thyroid storm, MMI intolerance, and IF the patient was pregnant and in their FIRST trimester?

propylthiouracil (PTU)

After control of a thyroid storm utilizing propylthiouracil, what should you use next?

methimazole

Dosing for Propylthiouracil

300-600 mg/day in 3 divided doses

taper monthly to maintenance of 100-150 mg/day (3 divided doses)

Which anti-thyroid drug has more GI and liver damage adverse reactions?

propylthiouracil

Monitoring for Thioamides

baseline: free T4, TSH, WBC with differential

4-6 weeks: free T4 and TSH

every 6-12 months: TSH once euthyroid

MOA of Iodides

blocks acute thyroid hormone release

inhibit thyroid hormone biosynthesis

decrease thyroid size and vascularity

When should you give iodides in a thyroid storm?

1 hour AFTER giving anti-thyroid drugs

What agents are considered iodides?

SSKI and Lugol's Solution

Place in therapy for Iodides

1. thyroid storm causing cardiac decompensation

2. symptom control 7-14 days PRIOR to thyroid surgery

3. adjunct to inhibit hormone release 3-7 days AFTER radioactive iodine

What are some adverse effects of iodides?

may cause thirst, diarrhea, weakness, convulsions

salivary gland swelling

gynecomastia

MOA of radioactive Iodine

permanently disrupts thyroid hormone synthesis

with time thyroid follicles become necrotic and die

What are some contraindications to using radioactive iodine?

CHILDREN

PREGNANCY

Active Grave's ophthalmopathy

When should you give methimazole OR propylthiouracil in respect to radioactive iodine?

BEFORE and stop 3-4 days prior

When should you start IoDINe after radioactive iodine?

3-7 days after

Monitoring from Radioactive Iodine treatment

TSH and T4 in 4 weeks

Adverse effects of radioactive iodine

hypothyroidism

dysphagia

neck tenderness/swelling

What is the primary therapy for thyrotoxicosis with thyroiditis?

beta blockers (propranolol or nadolol, esmolol)

What are beta blockers used for relating to hyperthyroidism?

symptom control of palpitations, anxiety, tremor, or heat intolerance

What are the oral drugs of choice for beta blockers?

propranolol or nadolol

What are the IV drugs of choice for beta blockers?

esomolol

When are thyroid gland resection preferred?

cancer

large glands > 80 g

severe ophthalmopathy

lack of remission

Timing for surgery

Euthyroid: 6-8 weeks

IoDIDE given: 10-14 days BEFORE

Beta blocker several weeks prior and 7-10 days POST-op

Why is iodide given 10-14 days prior to surgery?

reduce vascularity

Teprotumum (Tepezza)

insulin like growth factor I receptor inhibitor

alternative for thyroid eye disease after steroids, orbital radiation, and surgery

Thyroid Storm

life-threatening emergency may be caused by withdrawal of anti-thyroid drugs, infection, trauma, surgery

What are some signs/symptoms of thyroid storm?

hyperthermia, tachycardia, tachypnea, dehydration, jaundice, N/V/D, delirium, psychosis, seizures, coma

Propranolol

can block conversion of T4 to T3

considered to be a drug of choice for beta blockers in a thyroid storm

If your patient scores a 45 and above on the thyroid storm diagnosis, how likely is that your patient does have a thyroid storm?

very very very likely

If your patient scores a < 25 on the thyroid storm scale, how likely does your patient actually have a thyroid storm?

low to none

Hydrocortisone

used in myxedema coma

for common adrenal insufficiency

What drugs are available in a rectal form for thyroid storm?

PTU, MMI, SSKI, or Lugol's solution

What is the preferred long term treatment of a thyroid storm?

methimazole

Long-Term treatment of hyperthyroidism

wean initial antithyroid dosing on discharge and prefer MMI

In patients with MI why should you be hesitant on providing T3 supplementation?

due to T3 cardiovascular symptoms/side effects

Risk factors to developing HYPOthyroidism

Female sex

history of Type 1 diabetes (or any autoimmune)

Increasing age

Adverse Effects of Iodides

causes thirst, diarrhea, weakness, convulsions

salivary gland swelling

gynecomastia

hypersensitivity

Adverse effects of surgery

hypothyroidism

vocal cord abnormalities

Adverse effects of Tepezza (Teprotunumab)

muscle spasm, alopecia, nausea, fatigue

What is a compelling indication to start antithyroid drugs in a patient with subclinical hyperthyroidism?

paroxysmal atrial fibrillation

Which treatment is typically recommended for management of a patient with active thyroid eye disease?

prednisone