Thyroid Disorders Part 2 Flashcards
State of excessive levels of T3 and T4
Thyrotoxicosis
Increased state of thyroid function
Hyperthyroidism
What causes primary hyperthyroidism?
Excessive release of T3 and T4 by thyroid
What causes secondary hyperthyroidism?
Excessive release of TSH by pituitary
What causes tertiary hyperthyroidism?
Excessive release of TRH by hypothalamus
What is the epidemiology of thyrotoxicosis?
5% of women >60 y/o, women (5x more common), smokers, + family history of autoimmune thyroid disease
What is the most common cause of thyrotoxicosis?
Graves’ disease
Describe Graves’ disease
Autoantibodies bind TSH receptor in thyroid gland, causing excessive thyroid function
Thyroid stimulating Ig is most common (65%), but can also see anti-TPO (75%) and anti-Tg (55%)
What is the most common onset of Graves’ disease?
Women ages 20-40
What are s/s of Graves’ disease in addition to s/s of thyrotoxicosis?
Infiltration opthalmopathy and infiltration dermopathy
B/c Igs like extraocular muscles and skin
What is another name for thyroid-stimulating Ig lab test?
TSH receptor antibodies, TSHrAb
Why would you order a TSI (thyroid-stimulating Ig)?
Assist with diagnosis of Grave’s disease as a follow-up to abnormal thyroid function studies
What factors can interfere with readings of TSI
Recent administration of radioactive iodine (can suppress Ig)
Titers may not decline for up to 1 year after treatment so not used for treatment monitoring
If a TSI is ordered and comes back high, what is the interpretation?
Graves Disease or neonatal thyrotoxicosis
Could elevated TSI during pregnancy cause hyperthyroidism in a fetus/neonate?
Yes
What are etiologies of thyrotoxicosis?
Excessive iodine, thyroiditis, thyroid nodules, medications, hCG, thyrotoxicosis factitia, ectopic thyroid tissue, TSH hyper secretion
What are causes of excessive iodine leading to thyrotoxicosis?
Iodinated radiocontrast dye, high-iodine foods, medications: potassium iodine, amiodarone, iodinated topical antiseptics (povidone iodine)
Amiodarone is 37% iodine!
What are causes of thyroiditis leading to thyrotoxicosis?
Infectious/subacute thyroiditis, silent/postpartum thyroiditis
What are causes of thyroid nodules that can lead to thyrotoxicosis?
Toxic multinodular goiter, single toxic adenomas
What medications can cause thyrotoxicosis?
Chemotherapy and MS medications
What can cause elevated hCG leading to thyrotoxicosis?
Pregnancy, gestational trophoblastic disease, testicular cancer
What can cause thyrotoxicosis factitia leading to thyrotoxicosis?
Intentional or accidental ingestion of exogenous thyroid hormone
What can cause ectopic thyroid tissue leading to thyrotoxicosis?
Struma ovarii, metastatic thyroid cancer
What are symptoms of thyrotoxicosis?
General: fatigue and weakness, weight loss with increased appetite
Psych: nervousness/restlessness, hyperactivity/irritability
Cardio: palpitations/angina
MSK/neuro: muscle cramps
GI/GU: polyuria, diarrhea
Endo/reproductive: heat intolerance and sweating, oligomenorrhea
All of your metabolic processes are sped up including GI/GU muscles—>polyuria, diarrhea; heart: palpitations, brain: hyperactive
You are already so ramped up you can’t stand more heat!
Your body is working over time so it’s tired and it’s breaking things down so you lose weight and want to eat
What are signs of thyrotoxicosis?
General: thin body habitus (you are breaking stuff down and metabolism sped up!)
Psych: agitation, restlessness (so amped up!)
Cardio: tachycardia, atrial fibrillation
MSK/Neuro: muscle weakness (protein catabolism), hyperreflexia, osteoporosis, fine resting tremors
Endo/reproductive: goiter/thyromegaly
Skin: warm, moist skin
Eyes: lid lag or lid retraction
What are manifestations of Graves opthalmopathy?
Upper eyelid retraction
Lid lag with downward gaze
Staring appearance
May see conjunctival edema and inflammation
What are manifestations of thyroid acropachy?
Digital clubbing
Swelling of fingers and toes
Periosteal reaction of extremity bones
This is a rare skeletal complication of Grave’s disease
What are manifestations of Graves dermopathy?
Erythematous, rough plaques
Lymphoid infiltration and glycosaminoglycans accumulation in affected skin
Glycosaminoglycans are polysaccharides involved in cell growth/proliferation
What are cardiopulmonary manifestations of thyrotoxicosis?
Forceful heartbeat
Exertional dyspnea, pulmonary HTN (49%)
Abnormal conduction: premature atrial contractions, sinus tachycardia, atrial tachycardia, atrial fibrillation
—>more severe in men, elderly, pts with pre-existing heart disease
Can lead to cardiomyopathy
Atrial fibrillation may cause heart failure
Can cardiopulmonary manifestations of thyrotoxicosis be reversed?
Yes, often partially or fully reversible with thyrotoxicosis treatment
When do pregnant women often have remission of graves?
Late second trimester
What are pregnancy complications of untreated thyrotoxicosis?
Maternal: preeclampsia-eclampsia, maternal heart failure, thyroid storm
Fetal: miscarriage, preterm delivery, placental abruption, neonatal thyrotoxicosis
Why would a pregnant patient see an improvement in Grave’s disease during the course of her pregnancy?
Pregnancy causes inhibition of immune system so fetus is not rejected and grave’s disease is due to immunoglobulins
Divya is a 37-year-old female who was just diagnosed with primary hyperthyroidism. She has not received any clinical interventions to treat her hormone status. What would we expect her T4, T3, TSH, and TRH level to be?
T4: increased
T3: increased
TSH: decreased
TRH: decreased
How are patients with suspected thyrotoxicosis screened?
Serum TSH (+/- FT4)
What lab abnormalities other than T4, T3, TSH, TRH can be seen with thyrotoxicosis?
Hypercalcemia, increased alkaline phosphatase, anemia, decreased granulocytes
(Thyroid hormones cause bone resorption —> hypercalcemia, alkaline phosphatase is an enzyme involved in bone, anemia due to bone marrow depression and altered iron metabolism, same with granulocytes)
If a patient has Grave’s disease, which immune globulin is most likely to be responsible?
TSI followed by anti-TPO, anti-Tg
(TSI=thyroid-stimulating Ig)
If thyroiditis what abnormalities are often seen on labs?
Increased ESR, negative anti thyroid antibodies
If thyrotoxicosis factitia, what is often seen on labs?
Low serum thyroglobulin levels
(They took excess thyroid medication, so thyroid precursors will be low)
What is radioactive iodine uptake/scanning used for? Why is it helpful?
Thyrotoxicosis analysis; helps determine etiology by measuring thyroid metabolism by radioactive tracer iodine uptake
If there is elevated radioactive iodine uptake, what condition may be present?
Graves’ disease, toxic solitary nodule, toxic multinodular goiter, type I amiodarone thyrotoxicosis
If there is decreased radioactive iodine uptake, what conditions may be present?
Thyroiditis, iodine-induced thyrotoxicosis, type II amiodarone thyrotoxicosis
Who should not be given radioactive iodine uptake/scanning?
Pregnant women, or if you suspect cancer (does not differentiate)
Why would you order thyroid ultrasound?
Evaluation of thyromegaly, nodules
This diagnostic imaging test can identify areas of increased blood flow and supplement ultrasound
Color flow Doppler sonography
What are opthalmic complications of thyrotoxicosis?
Severe opthalmopathy can cause extraocular muscle entrapment, diplopia, optic nerve compression, and corneal drying with incomplete lid closure
Ocular myasthenia gravis is also associated
How are opthalmic complications of thyrotoxicosis treated?
Steroid therapy or, if severe, radiation or surgery
What are cardiac complications of thyrotoxicosis?
Arrhythmias, heart failure
May need treated with cardiac medications (BBs, digoxin, anticoagulation)
What are cardiac complications of thyrotoxicosis?
Dyspnea, pulmonary hypertension
How can thyrotoxicosis impact electrolytes?
Calcium: hypercalcemia, osteoporosis, nephron alcanos is
Hypokalemic periodic paralysis: symmetric flaccid paralysis after IV dextrose, oral carbs, or vigorous exercise- in Asian or American Indian men
Severe, life-threatening thyrotoxicosis
Thyroid storm
What can trigger thyroid storm?
Illness, RAI administration, thyroid surgery
How does thyroid storm manifest?
(Similar to thyrotoxicosis, but worse)
Marked delirium
Severe tachycardia
Vomiting and diarrhea
Dehydration
Very high fever (from high metabolic activity)
How is thyroid storm treated?
Thiourea drug
Iodinated contrast agent
Beta blocker
Hydrocortisone
Avoidance of aspirin therapy (NSAIDs bind to proteins in blood)
Definitive treatment: radioactive iodine or surgery
What thiourea drugs can be used for treatment of thyroid storm and what is their mechanism of action?
Methimazole or PTU: inhibit oxidation of iodine, prohibiting thyroid hormone formation
What iodinated contrast agents can be used for treatment of thyroid storm? What is their mechanism of action?
Ipodate sodium or iopanoic acid: inhibit peripheral conversion of t4 to T3
What beta blockers can be used for treatment of thyroid storm and what is their function?
Propranolol or atenolol: relives symptoms of tachycardia, tremor, anxiety
Normal serum FT4 and T3 with low TSH
Subclinical hyperthyroidism
What are manifestations of subclinical hyperthyroidism?
Asymptomatic or mild hyperthyroid s/s, higher risk of complications like osteopenia/osteoporosis and cardiac arrhythmias
How is subclinical hyperthyroidism treated?
Observation if no s/s
Evaluation and treatment of cause: if TSH <.1 mlU/L, if symptomatic, or if high risk for complications
What is the prognosis of subclinical hyperthyroidism?
1-2% per year progress to symptomatic thyrotoxicosis
If multinodular goiter: 5% per year progress
Excess ingestion of which food product can cause hyperthyroidism? (Red meat, chamomile tea, kelp supplements, omega-3 fatty acids)
Kelp supplements (high iodine content)
While useful to evaluate thyroid disease, thyroid ultrasonography is limited in that it cannot…
(Assess metabolic activity of a thyroid mass, distinguish a solid mass from a cystic mass, assess blood flow to the thyroid gland, evaluate smooth versus poorly defined mass margins)
Assess metabolic activity of a thyroid mass
Untreated hyperthyroidism could eventually lead to all of the following complications, except…
(Osteoporosis, peripheral edema, edema, atrial fibrillation)
Peripheral edema, edema
How is Grave’s disease treated?
Beta blockers
Iodinated contrast agents
Thiourea drugs
What beta blockers can be given for grave’s disease and why?
Propranolol, atenolol: improve tachycardia, palpitations, anxiety, tremor, etc
Often given initially for s/s until anti thyroid therapies have chance to work
What iodinated contrast agents are given for Grave’s disease and why?
Iopanoic acid, ipodate sodium: block conversion of T4 to T3
Given to severely symptomatic thyrotoxic patients but efficacy wanes over time
What thiourea drugs can be given for Grave’s disease and what is their mechanism of action?
Methimazole, propylthiouracil: inhibit production of thyroid hormone without permanent damage to thyroid
Which patients are thiourea drugs particularly useful in?
Mild cases, elderly, young adults, patients who cannot have more definitive treatments, to prepare for RAI or surgery
What side effects are associated with thiourea drugs?
Agranulocytosis and pancytopenia
Which thiourea drug is preferred for most patients? Which one is preferred if first trimester or breastfeeding?
Methimazole: preferred in most patients
Propylthiouracil (PTU): preferred if first trimester or breastfeeding
What is the mechanism of action of Methimazole?
Inhibits organification of iodine, blocking formation of thyroid hormone
What are indications for Methimazole?
General hyperthyroidism, hyperthyroidism due to Graves’ disease
Methimazole carries a greater risk of ______ and _____ than PTU
Teratogenicity, goes more into breast milk
What are side effects of Methimazole?
Derm: pruritis, rash urticaria
MSK: joint pain
GI: abnormal taste, N/V, hepatotoxicity (less than PTU)
Heme: agranulocytosis (greatest risk in first 2-3 months of tx)
What are contraindications of Methimazole?
Hypersensitivity to prescription
What should you monitor while a patient is on Methimazole?
Thyroid labs, CBC, liver functions tests
What is the mechanism of action of propylthiouracil?
Inhibits organification of iodine, blocking formation of thyroid hormone; also decreases peripheral tissue conversion of T4 to T3
What are indications of propylthiouracil?
Hyperthyroidism
Propylthiouracil has greater risk of _____ than Methimazole and has a _______
Hepatotoxicity, black box warning
What are side effects of propylthiouracil?
Derm: pruritis, rash, urticaria
MSK: joint pain
GI: abnormal taste, N/V, hepatotoxicity (higher risk than methimazole)
Heme: agranulocytosis (highest risk in first 2-3 months of treatment)
Reproductive: lower risk of teratogenicity and breast milk transmission
What are contraindications of propylthiouracil?
Hypersensitivity, in Canada breastfeeding is also CI (allowed in US)
What should be monitored with treatment with PTU?
Thyroid labs, CBC, liver function tests
Which of the following tests would be helpful when choosing whether to put a patient on methimazole or PTU?
(A urine hCG test, a comprehensive metabolic panel, a CBC, all of the above)
All of the above
What is definitive treatment of Grave’s disease?
Destruction of overactive thyroid tissue via radioactive iodine or surgery
Who should not receive radioactive iodine?
Pregnant or breastfeeding
Methimazole use within 4 days
Steroid use (can worsen opthalmopathy)
Who should receive surgery for Grave’s disease?
Pregnant women, pts who do not wants radioactive treatment, or if suspicion of malignancy
What is the surgical procedure of choice for Grave’s disease?
Total resection of lobe and subtotal resection of other lobe with thiourea drugs pre-op to ensure patients euthyroid at surgery
What are complications of surgery for Grave’s disease?
Damage to recurrent laryngeal nerve, hypo parathyroid is
How is thyrotoxicosis due to toxic solitary nodule treated?
Evaluate with fine needle aspiration to rule out cancer
Symptomatic-BB+methimazole or PTU (keep TSH slightly suppressed to inhibit further growth of nodule)
Surgery: if patient is <40 y/o or in healthy older patients
RAI may be given to patients who are not surgical candidates
How is amiodarone-induced thyrotoxicosis treated?
Symptomatic: BB + methimazole (adjunct therapy of iodinated contrast agent if needed)
D/C amiodarone does not have a significant impact for several months
Surgery for refractory cases
How is thyrotoxicosis due to toxic multinodular goiter treated?
Symptomatic: BB + methimazole or PTU (95% recurrence if thiourea drug is discontinued)
Surgery: definitive treatment; total or near-total thyroidectomy—> relieves feeling of pressure and visible external swelling, allows for evaluation and removal of occult cancers
RAI may be given to patients who are not surgical candidates
How is thyrotoxicosis due to thyroiditis treated?
Thioureas: ineffective; thyroid hormone production is low
Symptomatic: BB therapy; iodinated contrast agents if severe, NSAIDs or opioids as adjunct for pain management
Which of the following patients would be most likely to receive an iodinated contrast agent as treatment?
(A patient who is pregnant or breastfeeding, a patient who is relatively young and healthy, a patient who presents to the ER with thyroid storm, a patient with moderate s/s who is not a good surgical candidate)
A patient who presents to the ER with thyroid storm
A patient with a toxic multinodular goiter has been symptom-free for 15 years with the use of atenolol and methimazole. She decides to stop her medication, as she thinks it is likely that she no longer actually needs it. What would we expect to happen?
(The patient is likely to have a recurrence of her thyrotoxicosis
The patient may have a recurrence of thyrotoxicosis, but is much less likely to have s/s if she follows a low-iodine diet
The patient is unlikely to have a recurrence of her thyrotoxicosis as she has been symptom free for over one decade
The patient is unlikely to have a recurrence of her thyrotoxicosis, but may experience signs and symptoms of hypothyroidism)
The patient is likely to have a recurrence of her thyrotoxicosis
What are etiologies of thyroiditis?
Hashimoto (autoimmune thyroiditis), painless postpartum thyroiditis and painless sporadic thyroiditis (these are both “silent thyroiditis) subacute thyroiditis, suppurative thyroiditis, ríe del thyroiditis
This is the most common thyroid disorder in the US. It is more common in women and is associated with anti-TPO and anti-Tg. It may transiently cause hyperthyroidism but typically progresses to hypothyroidism over time
Hashimoto thyroiditis
What are risks for development of Hashimoto thyroiditis?
Head-neck radiation, +family history, hepatitis C, iodine deficiency
This condition occurs after delivery in women (7%) and manifests as transient hyperthyroidism followed by transient hypothyroidism. There is a high chance of recurrence in subsequent pregnancies
Thyroid autoantibodies, particularly anti-TPO are usually present
Painless postpartum thyroiditis
Subacute form of Hashimoto thyroiditis similar to painless postpartum thyroiditis, but not associated with pregnancy
Painless sporadic thyroiditis
This form of thyroiditis is believed to be due to a viral infection. What are other names for it?
Subacute thyroiditis, de Quervain thyroiditis, granulomatous thyroiditis, giant cell thyroiditis
Who most commonly gets subacute thyroiditis?
Young and middle-aged women in the summer
This is a non viral thyroid gland infection that is rare in non-immunosuppressed patients
Suppurative thyroiditis
This is the rarest thyroiditis that is often due to systemic fibrosis. What are it’s names?
Riedel thyroiditis, riedel strums, wordy or igneous thyroiditis, invasive fibrous thyroiditis
What is the most common population to get riedel thyroiditis?
Middle aged or elderly women
What is the presentation of Hashimoto thyroiditis?
Diffusely enlarged, firm, finely nodular thyroid
Usually no pain or tenderness, sometimes tight feeling in neck
Often complain of hypothyroid symptoms
More prone to depression and fatigue even once thyroid labs WNL
What is the clinical presentation of painless postpartum thyroiditis?
May have some thyroid enlargement
Transient hyperthyroidism 1-6 months after delivery that lasts 1-2 months
Hypothyroidism follows and lasts a few months
What is the clinical presentation of painless sporadic thyroiditis?
Small, non tender goiter (50%)
Transient hyperthyroidism x 1-2 months
Transient hypothyroidism for a few months
What is the clinical presentation of subacute thyroiditis?
Acute enlargement of thyroid gland often associated with pain referred to ear or jaw and dysphagia
May see malaise and low-grade fever
Often with history of recent URI
Thyrotoxicosis for 4 weeks, then hypothyroidism x 4-6 months
Some have persistent hypothyroidism
What is the clinical presentation of suppurative thyroiditis?
Severe pain, tenderness, redness, and fluctuance associated with the thyroid gland
Often with associated fever
Typically history of immunosuppression
What is the clinical presentation of Riedel thyroiditis?
Asymmetric, stony, adherent thyroid gland
May have associated dysphagia, dyspnea, pain, hoarseness
What diagnostic labs are abnormal for Hashimoto thyroiditis?
Anti-TPO and/or anti-Tg antibodies: helpful for diagnosis but not disease monitoring
May have thyroid labs consistent with hyper- or hypothyroidism
Some patients have serum antibodies consistent with celiac disease
What diagnostic labs will be abnormal with subacute thyroiditis?
Markedly elevated ESR levels but low anti thyroid antibody titers
May have thyroid labs consistent with hyper-or hypothyroidism
What diagnostic labs will be abnormal for suppurative thyroiditis?
Elevated ESR and leukocytes
Often normal thyroid function studies and anti thyroid antibodies
This type of thyroiditis will have normal thyroid labs, or signs of hyper- or hypothyroidism but no other abnormalities on labs
Riedel thyroiditis
Which type of thyroiditis is strongly correlated with immunosuppression?
Suppurative thyroiditis
The underlying etiology of postpartum thyroiditis is
An autoimmune process
Anti-TPO is AKA _____
Anti thyroid peroxidase antibody, TPO-Ab
What is anti-TPO used for?
Diagnosis of autoimmune thyroid disease especially Hashimoto Thyroiditis and can be seen with Graves Disease
What are interfering factors with anti-TPO test?
12-15% of normal females and 1-3% of normal males have anti-TPO
If anti-TPO comes back high, what should you think?
Autoimmune thyroid disease: Hashimoto thyroiditis, Graves’ disease
Other thyroid conditions: cancer, goiter
Other AI conditions: RA, pernicious anemia, rheumatoid-collagen disease
What are other names of anti-Tg?
Thyroid autoantibody, thyroid antibody
What are uses of anti-Tg?
Assists with diagnosis of autoimmune thyroid disease
Especially Hashimoto thyroiditis (70%), graves disease (55%)
What are interfering factors with anti-Tg?
Some normal females and normal males have anti-Tg
If anti-Tg is high, how can this be interpreted?
Hashimoto thyroiditis, Graves’ disease, cancer goiter, RA, pernicious anemia, rheumatoid collagen disease
What can a thyroid ultrasound be used to diagnose?
Hashimoto thyroiditis- diffuse heterogeneous texture
Suppurative- can identify presence of abscess
Hyperthyroidism: can help distinguish cause; if Graves’ disease will see increased vascularitis or thyroiditis normal or decreased vascularity
What is RAI uptake scanning useful in?
Distinguishing graves from thyroiditis with hyperthyroidism
Graves’ disease: increased RAI uptake
Thyroiditis: decreased RAI uptake
What would a FNA biopsy be useful for?
Hashimoto thyroiditis: nodules carry 8% chance of cancer
Suppurative: FNA biopsy with gram stain and culture required
What are complications of thyroiditis abnormal thyroid function?
Thyrotoxicosis, thyroid storm, temporary or permanent hypothyroiditis
Higher risk of depression
Pressure on local neck structures
What are complications of Hashimoto?
Higher risk of 1st trimester spontaneous miscarriage (if untreated)
What are complications of suppurative thyroiditis?
Abscess and/or chronic sinus tract formation
Cancer is associated with _____
Chronic thyroiditis
How is Hashimoto thyroiditis treated?
May observe if asymptomatic and minimally enlarged or normal size thyroid gland
Hypothyroidism- replacement with levothyroxine
Large gland/goiter- may try levothyroxine suppressive therapy
How is subacute thyroiditis managed?
High-dose aspirin or NSAIDs are treatment of choice
+/- corticosteroids for severe or refractory cases
BB can be helpful for acute symptoms
Severe thyrotoxicosis- iodinated contrast agents
What is the treatment of suppurative thyroiditis?
Antibiotics, surgical drainage of abscess
What is the treatment of riedel thyroiditis?
Tamoxifen and/or steroid therapy
Surgery for decompression if needed
A patient has a nonspecific diagnosis of thyroiditis on her chart. Which type of thyroiditis would be most likely to have positive thyroid autoantibodies?
Hashimoto thyroiditis
A patient tells you that she had thyroiditis a few months ago, but it got much better with ibuprofen and a medrol dose pack. Which type of thyroiditis is most likely to respond to these medications?
Subacute thyroiditis
State of abnormal thyroid function studies in the setting of severe non thyroidal illness
Often no history of thyroid gland or HPT axis dysfunction
Sick euthyroid syndrome
What is the general cause of sick euthyroid syndrome?
Thought to be due to cytokines, especially IL-6
Many causes (sepsis, starvation, burns, trauma, surgery, cancer, etc)
What will labs look like in sick euthyroid syndrome?
Varying abnormalities in TSH, T3, T4, rT3, and FT4 depending on severity and underlying cause of illness
What is the pathophysiology of sick euthyroid syndrome?
Impaired deiodination of T4 to T3
Decreased clearance of reverse T3
Cytokine-based inhibition of thyroid production
Impaired accuracy of thyroid labs in severe illness
What is management of sick euthyroid syndrome?
Observation without administration of thyroid hormone unless patient has history of pre-existing hypothyroidism or clinical s/s of hypothyroidism
Controversial!
What is the prognosis of sick euthyroid syndrome?
Correction of underlying disease usually results in return of thyroid labs/function to normal status
What populations are thyroid nodules/goiter very prevalent?
Women
Highly prevalent in iodine-deficient areas and increased age
Non-palpable nodules are commonly found on autopsy (60%) and 30% of patients in US
50% of palpable nodules are multinodular
Most patients with thyroid nodules/goiter are _____, but there are higher rates of _______ than average patient
Euthyroid
Hypothyroidism, hyperthyroidism
Cancer is present in ___ of palpable thyroid nodules. What increases risk?
10%
Head/neck or total body radiation
+family history of thyroid cancer
Increased risk with large nodules, adherence to local structures, hoarseness or vocal cord paralysis, lymphadenopathy
What are signs and symptoms of small, solitary nodules?
Typically asymptomatic and may be incidentally found
What are signs and symptoms of large multinodular goiters?
Swelling, hoarseness, dysphagia
Retrosternal: dyspnea, facial erythema, jugular vein distension
What abnormal thyroid function can be due to thyroid nodules/goiter?
Hypothyroidism- Hashimoto thyroiditis, iodine deficiency, some nontoxic multinodular goiters, some simple goiters
Hyperthyroidism- Graves’ disease, toxic nodular goiter, subacute thyroiditis, differentiated thyroid cancer, solitary hyper functioning nodules
Euthyroidism- some nontoxic multinodular goiters, some simple goiters
What diagnostic testing should be done on thyroid nodules/goiters?
TSH +/- FT4, autoimmune labs
Thyroid US to evaluate size and characteristics of nodule and if nodule is part of MNG or solitary
What are concerning features of thyroid nodule/goiter on thyroid US?
Cystic lesions are usually benign
Irregular margins, solid lesions, heterogeneous texture, abnormal vascularity, microcalcifications, larger nodules
Why would a RAI uptake be helpful in evaluating a thyroid nodule/goiter?
Evaluation of hyper functioning thyroid tissue
What are results of the RAI uptake study?
Hypofunctioning nodules will be “cold” with little uptake —> higher cancer risk
Hyper functioning nodules will be “hot” with high uptake —> lower cancer risk
What is a CT scan used for with a thyroid nodule/goiter?
To delineate large nodules or MNG degree of extension into mediastinum and presence of tracheal compression
What is the most commonly used diagnostic testing to evaluate thyroid nodules for malignancy?
Fine-needle aspiration biopsy
How would find needle aspiration biopsy evaluate MNG? Solitary nodules?
Biopsy of 4 largest nodules and any specific nodules of concern
Biopsy of solitary nodules indicated if 1+ cm and suspicious appearance, 2 cm or larger, associated cervical lymphadenopathy, nodule is growing
What is the prevalence of false +/- results of a fine-needle aspiration biopsy?
4%
How is thyroid nodule/goiter managed?
General follow-up: regular palpation and US imaging every 6 months initially, then yearly after stable; avoidance of excessive iodine intake
LT4 suppression if nodule >2 cm and normal or high TSH to reduce emergence of new nodules
Thiourea drugs +/- BB if s/s of thyrotoxicosis
Surgery if cancer, hyper functioning nodules, toxic MNG
Ethanol injection for shrinkage of benign nodules
RAI therapy for toxic thyroid adenomas, toxic MNG, Graves’ disease to shrink nodules
What are the risks of LT4 suppression?
Heart disease exacerbation, osteoporosis, hyperthyroidism
What are risks of RAI therapy?
Hypothyroidism
You’re having a thyroid ultrasound done for a mass that was palpated on exam. Which statement from the sonographer would be most reassuring?
I see a few calcified areas
It looks like it’s filled with fluid
There is a lot of blood going to this nodule
It’s really hard to see the edges; they’re very irregular
It looks like it’s filled with fluid
What treatment would be most effective to eradicate a 3-cm thyroid nodule with cells concerning for carcinoma on FNA biopsy?
Radioactive iodine, surgical excision, levothyroxine suppression, methimazole +/- propranolol
Surgical excision
What is the prevalence of thyroid cancer?
More common in women, increasing incidence with age, most common endocrine cancer
What is the MC thyroid cancer?
Papillary thyroid carcinoma
How does papillary thyroid carcinoma usually present?
As a single thyroid nodule
Palpable cervical lymphadenopathy (10%)
Occult lung metastases (10-15%)
Least aggressive form of thyroid cancer: slow-growing, often confined to thyroid/regional lymph nodes, high survival rates
Some (not much) radioactive iodine uptake
Papillary thyroid carcinoma can occur as ______
Autosomal dominant trait
This is the 2nd MC thyroid cancer and is likely to metastasize. It has high levels of iodine uptake so RAI scanning and treatment is effective
Follicular thyroid carcinoma
This thyroid cancer represents 3% of thyroid cancers. It can secrete calcitonin, prostaglandins, 5HT, ACTH, and CRH
It often has early metastases at time of diagnosis and does not have good iodine uptake
Medullary thyroid carcinoma
This type of thyroid cancer represents 2% of thyroid cancers and is the most aggressive with the worst survival. The classic presentation is a rapidly enlarging mass in MNG
Does not have good iodine uptake
Anaplastic thyroid carcinoma
What is present on physical exam of thyroid cancer?
Palpable, firm, no tender thyroid nodule or mass
What are symptoms of thyroid cancer?
Often asymptomatic may see neck discomfort, dysphagia, hoarseness and occasionally symptoms of hyper- or hypothyroidism
Lymph node involvement more common in children
M/C sites are local lymph nodes, lungs, bones
What are symptoms of anaplastic thyroid cancer?
S/s of metastasis and local invasion
What are s/s of medullary thyroid cancer?
May present with flushing and diarrhea, rarely Cushing-like symptoms
Hyperthyroidism may be present in which type of thyroid cancer?
Follicular thyroid carcinoma
Elevated serum thyroglobulin is seen in which types of thyroid cancer?
Metastatic papillary and follicular CA
Limitations: invalid if anti-Tg present; may be falsely elevated in thyroiditis
Elevated serum calcitonin will be seen in which thyroid cancer?
What are limitations of this test?
Medullary thyroid carcinoma
Also high in thyroiditis, pregnancy, azotemia, hypercalcemia, other cancers
Most useful to diagnosis if very high levels or serially increasing levels
Which thyroid cancer has elevated serum CEA?
What are limitations of this test?
Medullary thyroid carcinoma
Also elevated in other cancers
Can be used as an adjunct to help evaluate medullary thyroid carcinoma
What are uses of Tg lab test?
Assist with evaluating extent of papillary and follicular thyroid cancers, their prognosis, and their response to treatment. Steadily rising Tg can help identify tumor recurrence
What are interfering factors with Tg results?
Elevated in benign condition (thyroiditis, post-thyroid exam)
Thyroid HRT can suppress residual or metastatic thyroid tissue and cause falsely low Tg levels
Anti-Tg antibodies can cause false readings
If a Tg lab value comes back high, what should you be thinking?
Cancer- papillary or follicular thyroid cancer
Others- thyroiditis, thyroid trauma, or recent exam
A patient newly diagnosed with thyroid cancer has not only abnormal thyroid function labs, but also abnormal levels of non-thyroid-related labs such as calcitonin and serotonin. What type of thyroid cancer is most likely?
Medullary
What are uses for calcitonin thyroid lab?
For medullary thyroid carcinoma to evaluate extent of cancer and response to treatment
Secreted by parafollicular cells of thyroid gland
Normally stimulated by elevated serum calcium levels
May help screen patients with + family history of medullary thyroid carcinoma
What are interfering factors with calcitonin values?
Elevated in pregnancy and neonates
elevated in patients taking certain meds including calcium, oral contraceptives
If a calcitonin lab value is high, what should you suspect?
Medullary thyroid carcinoma
Non-cancer thyroid disorders: parafollicular cell hyperplasia, thyroiditis
Other cancers: breast, pancreatic, lung
Others: hyperparathyroidism, cirrhosis, pernicious anemia
What is the use of CEA as a thyroid lab?
Evaluation of extent of certain cancers (medullary thyroid+ non thyroid), and response to treatment
Steadily rising CEA levels can help identify tumor recurrence
What are interfering factors with CEA?
Elevated in smokers and due to many non cancerous diagnosis
Not all cancers in target tissues produce CEA
If CEA is high, what should you suspect?
Cancer- GI, breast, lung, pancreatic, hepatobiliary, medullary thyroid
Others-inflammation, cirrhosis, peptic ulcer
Why would a thyroid ultrasound be helpful for thyroid cancer?
Determining size and location of mass, more sensitive than CT or MRI for neck metastases
Why would a RAI scan be useful for thyroid cancer?
Can use after thyroidectomy to do whole-body scans
May reveal presence of metastatic tissue
But not all thyroid cancers concentrate iodine well
Why would a CT or MRI be helpful in diagnostic of thyroid cancer?
To help evaluate distant metastases or delineate retrosternal masses
Why would PET scan be helpful in thyroid cancer?
Helpful for detecting Mets not visible on RAI scanning
But lacks specificity for thyroid cancer and is expensive
What is treatment of choice for thyroid cancers?
Surgery
If a mass is >1 cm and known to be cancer, how should it be managed?
Total thyroidectomy+ cervical lymph node dissection
If a mass is <1 cm and known to be cancer, how should it be managed?
May consider lobe to my if well-differentiated and patient is young, no lymph node involvement seen on US and no history of risk factors such as radiation exposure
If < 4 cm indeterminate lesion present, how should it be managed?
Lobectomy +/- later thyroidectomy
If >4 cm indeterminate lesion, how should it be managed?
Total thyroidectomy
What are complications of surgery?
Laryngeal nerve palsy or permanent injury, hypoparathyroidism, airway swelling, bleeding, infection
What patients would you consider management with thyroxine suppression for? What should you consider?
Differentiated thyroid cancers
Must monitor thyroid labs; consider periodic bone density screening
TSH should be <.1 mIU/L or <.05 mIU/L for more advanced cancers
What thyroid cancer patients would you consider RAI therapy for? What are considerations?
Differentiated thyroid cancers
Done post-operatively or for patients who cannot have surgery
CI in women who are pregnant or nursing, or who lack childcare
Patients must take a low-iodine diet for 2 weeks prior
Not helpful if cancer undifferentiated
What thyroid cancer patients would you consider thyroxine suppression for? What are considerations?
Differentiated thyroid cancers
Must monitor thyroid labs; consider periodic bone density screening
TSH should be <.1 mIU/L or <.05 mIU/L for more advanced cancers
Who would you consider giving chemotherapy to for thyroid cancer?
Aggressive differentiated cancers
What is the treatment for anaplastic thyroid carcinoma?
Local resection and radiation, is unresponsive to RAI and most chemotherapies
What is recurrence of thyroid cancer?
Most differentiated cancers recur within 5-10 years after treatment
How is thyroid cancer monitored?
Yearly thyroid US; thyroglobulin (if appropriate)
Monitor thyroid function studies to ensure adequate hormone levels
TSH: should be suppressed (goal is <.mIU/L)
RAI scan: may be ordered if cancer was well differentiated
What is the prognosis of thyroid cancer?
> 90% 10-year survival rates of papillary and follicular thyroid carcinomas
78% 10-year survival rate of medullary thyroid carcinoma
7% anaplastic thyroid carcinoma
