PA301 - Endocrine Packet #3

What is hyperthyroidism?

excess of thyroid hormone (T3, T4) produced by thyroid gland

What do labs demonstrate with hyperthyroidism?

low TSH and high T3, T4

What is the most common cause of hyperthyroidism?

Graves disease

What is Graves disease?

-autoimmune disorder (not like others -> does not attack body)

-thyroid stimulating autoantibodies activate thyroid stimulating hormone receptors (mimic TSH)

What are other causes of hyperthyroidism?

-autonomous thyroid nodules (start making thyroid hormone on their own and do not listen to pituitary)

-thyroiditis

What are signs and symptoms of hyperthyroidism?

-heat intolerance

-anxiety

-heart palpitations

-unintentional weight loss

-tremors

-insomnia

(think fast)

What are the physical exam findings for hyperthyroidism?

general:

-hyperactivity

-weight loss

organ specific:

-skin: warm, moist, thinning and fine hair

-ENT: lid lag, exophthalmos (G), periorbital and conjunctival edema (G), goiter

-heart: tachycardia, irregularly irregular pulse if atrial fibrillation present, hypertension

-MS: tremor, proximal muscle weakness, hyperreflexia (can lead to osteoporosis)

What is lid lag?

-see sclera when looking down

-lid doesn't follow eyeball

What is exophthalmos?

-bulging eyes

-retracted eyelids (eyelids don't close all the way when blinking)

-eye redness (dry eyes and not lubricated)

What is periorbital edema?

swelling around the eyes

What is included in differential diagnosis of hyperthyroidism?

-euthyroid hyperthyroxinemia

-glucocorticoid therapy

-biotin therapy

What is euthyroid hyperthyroxinemia?

abnormalities in serum thyroid-binding proteins cause an elevation in total serum T4 concentrations and typically normal T3 and TSH levels

What is glucocorticoid therapy?

high-dose glucocorticoid therapy can lead to decreases in TSH, but free T4 and free T3 are also low or normal

What is biotin therapy?

ingestion of biotin can cause falsely low TSH with falsely elevated T4, T3, and TSH receptor-binding inhibitor immunoglobulin (TBII)

What is overt (clinical) hyperthyroidism?

high free T4 with low TSH

What is subclinical hyperthyroidism?

normal free T4 with low TSH

What is secondary disease of hyperthyroidism?

-rare, very rare

-high free T4 with high TSH (something wrong with pituitary)

What diagnostic study can you do for hyperthyroidism?

-thyroid radioactive iodine uptake and scan

-indicated if high free T4

-contraindicated during pregnancy and breastfeeding

-diffusely high uptake consistent with Graves

If a diagnosis cannot be made based on history and exam, what other diagnostic study can be done for hyperthyroidism?

-thyroid stimulating autoantibodies

-doppler ultrasound to measure blood flow (blood flow increased with hyperthyroidism)

What is treatment for Graves Disease?

-medical

-surgery

-radioactive iodine ablation

-treatment sometimes not indicated for subclinical disease

What is medical treatment for Graves disease?

-inhibit production of thyroid hormone

-first line: methimazole (can be hard on liver; small doses to start; contraindicated in pregnancy)

-pregnancy: propylthiouracil (PTU)

-beta blockers reduce symptoms but do not treat disease

What is surgical treatment for Graves disease (benefits and risks)?

-benefits: definitive treatment, guaranteed cure

-risks: guaranteed hypothyroid, requires replacement thyroid hormone

-amount removed depends on area affected

What are benefits and risks of radioactive iodine ablation for Graves disease?

-benefits: can prevent need for medications

-risks: increased risk of developing some cancers, but not guaranteed to restore euthyroidism (too much leads to hypothyroid)

What is the most reliable test for follow-up evaluation of Graves disease?

frequent early monitoring of free T4 since TSH levels may remain low for weeks after starting treatment

How often should labs be checked for patients on methimazole for Graves?

every 4-6 weeks until maintenance dose achieved (monitor LFT as well)

How often should labs be checked for patients on radioactive ablation for Graves?

every 4-6 weeks until hypothyroid and therapeutic level of levothyroxine achieved (monitor TSH as well)

How often should labs be checked for patients on surgical ablation for Graves?

free T4 at discharge and TSH at 6-8 weeks, adjust levothyroxine level accordingly

What is patient education for Graves disease?

-hyperthyroidism is a manageable disease

-requires lifelong monitoring to remain asymptomatic

What is thyroiditis?

umbrella term encompassing many disorders that cause inflammation of thyroid gland

What are the two categories of thyroiditis?

-painful thyroiditis: subacute, acute (suppurative), radiation-induced

-painless thyroiditis: Hashimoto (hypothyroidism), postpartum (hyperthyroidism), subacute lymphocytic, drug-induced

What are some types of thyroiditis?

-Hashimoto thyroiditis

-postpartum thyroiditis

-painless thyroiditis

-drug-induced thyroiditis

-infectious thyroiditis (subacute/acute thyroiditis)

What is the clinical presentation and course of disease for Hashimoto thyroiditis?

-clinical presentation: hypothyroidism

-course of disease: typically permanent in nature

What is the clinical presentation and course of disease for postpartum thyroiditis?

-clinical presentation: hyperthyroidism followed by hypothyroidism

-course of disease: must occur after delivery of baby; typical, resolution within 12-18 months

What is the clinical presentation and course of disease for painless thyroiditis?

-clinical presentation: hyperthyroidism followed by hypothyroidism

-course of disease: must not occur after delivery of baby; typically, resolution within 12-18 months

What is the clinical presentation and course of disease for drug-induced thyroiditis?

-clinical presentation: can manifest as hyperthyroidism or hypothyroidism

-course of disease: typically resolves shortly after cessation of medication use

What is the clinical presentation and course of disease for infectious thyroiditis (subacute thyroiditis, acute thyroiditis)?

-clinical presentation: painful thyroid gland, prodrome of myalgias, fever, and fatigue

-course of disease: subacute: transient hyperthyroidism lasting 3-6 weeks, subacute hypothyroidism lasting up to 6 months, with euthyroid levels achieved by 6-12 months

What are signs and symptoms of subacute/acute thyroiditis?

prodrome of cold-like symptoms

What are signs and symptoms of acute thyroiditis?

very tender, erythematous thyroid with fever, dysphagia, and dysphonia

What are signs and symptoms of Hashimoto's thyroiditis?

-fatigue

-cold intolerance

-weight gain

What are signs and symptoms of postpartum thyroiditis?

can be hypo or hyperthyroid

What is the difference between physical exam of Graves disease and subacute thyroiditis?

-Graves: exophthalmos, myxedema, goiter, thyroid bruit (whooshing sound due to increased blood flow); T4 goes up and TSH goes down and stays that way

-Subacute thyroiditis: tender to palpation; TSH and T4 alternate between up and down

What is included in the differential for thyroiditis?

-thyroid lymphoma

-Graves disease

What is thyroid lymphoma?

B-cell non-Hodgkin lymphoma that can be a complication of Hashimoto disease

What are the diagnostic studies for subacute thyroiditis?

-high ESR

-anemia

-leukocytosis with left shift

-negative thyroid autoantibodies

What are the diagnostic studies for acute thyroiditis?

-high ESR

-leukocytosis with left shift

-Gram stain

-culture

What are the diagnostic studies for Hashimoto's thyroiditis?

positive thyroid autoantibodies (Anti-TPO)

What are the diagnostic studies for subacute lymphocytic thyroiditis?

positive thyroid autoantibodies

What are the diagnostic studies for postpartum thyroiditis?

positive thyroid autoantibodies

What is the treatment for subacute thyroiditis?

-NSAIDs for pain

-consider prednisone if no improvement in 1 week

What is the treatment for acute thyroiditis?

-antibiotics

-may need surgical drainage

What is the treatment for radiation-induced thyroiditis?

-NSAIDs for pain

-rarely prednisone is needed

-beta blocker if hyperthyroid symptoms

What is the treatment for Hashimoto's thyroiditis?

levothyroxine

What is the treatment for postpartum and subacute lymphocytic thyroiditis?

-beta blockers if hyperthyroid

-levothyroxine if hypothyroid

What is the treatment for drug-induced thyroiditis?

-discontinue medication

-beta blocker or levothyroxine may be needed for persistent dysfunction

What is the patient education for thyroiditis?

-50% with postpartum disease will develop permanent hypothyroidism within 9 years of diagnosis

-preemptively counsel patients treated with drugs known to cause drug-induced thyroiditis

-follow-up care needed to prevent further progression of disease