Diseases of thyroid Flashcards
What is the function of the thyroid?
Helps regulate metabolism, regulate long bone growth and brain development
Physiology of thyroid hormones
TRH -> TSH -> Thyroxine -> T4 -> T3
Why is iodine so important?
Needed to produce T3 and T4. The T4 structure contains 4 iodine atoms
Deiodination leads to what?
Production of the potent hormone Tiiodothyronine (T3)
Thyrotoxicosis is what?
Elevated unbound “free” thyroid hormone circulating in the body
Most common cause of thyrotoxicosis?
Hyperthyroidism (90%)
What is the most common cause of Hyperthyroidism?
Graves Disease, F>M ratio 5:1
Graves disease typically effects who?
Women ages 20-40
Toxic Nodular goiter occurs in who?
Older population
3 causes of primary hyperthyroidism
- Graves disease (most common)
- Toxic Multinodular Goiter
- Toxic Nodular Goiter
Other causes of thyrotoxicosis ro hyperthyroidism
Subacute or post partum thyroiditis, Pituitary adenoma, Struma Ovarii, iodine induced hyperthyroidism (Jod-Basedow Dx), med induced, testicular germ cell tumors, palpation thyroiditis
What is elevated in pituitary adenomas?
TSH, T4 and T3
Which medications can induce hyperthyroidism?
Lithium and Amiodarone
How do germ cell tumors cause hyperthyroidism?
Stimulate TSH
Hyperthyroid symptoms
Irritability, nervousness, anxiety, restlessness, emotional lability, sweating, poor concentration, fatigue, muscle weakness/cramps, palpitations, increase bowel movements, SOB, heat intolerance, menstrual irregularities
PE findings skin/nails with hyperthyroidism
Pruritus, moist skin, thinning hair, hyperpigmentation, onycholysis
PE findings of HEENT with hyperthyroidism
Lid lag and stare, exopthalmus, goiter or nodules
PE findings of cardiac with hyperthyroidism
Tachy/AFIB, Neuro: fine tremor, hyperreflexia
PE findings of endocrine with hyperthyroidism
Weight loss despite increased appetite
Graves disease PE findings
Ophthalmopathy/exopthalmos, infiltrative dermopathy, thyroid acropathy, goiter with bruit
a pt with graves may experience all of hyperthyroid symptoms in addition to these
Hyperthyroid labs to draw
TSH, free T4, total T3, antibodies, serum cholesterol, calcium
What will a TSH show for hyperthyroidism?
Decreased
What will a free T4 show for hyperthyroidism?
Elevated
What will a total T3 show for hyperthyroidism?
Elevated
What will serum cholesterol be for hyperthyroidism?
Decreased
What will happen to calcium in hyperthyroid?
Hypercalcemia
Imaging studies for hyperthyroid
Nuclear scintigraphy w/RAIU: Thyroid scan with radioactive iodine uptake
Hyperthyroid treatment
Symptomatic Antithyroid drugs (Thionamides), Radioactive Iodine treatment (TOC), surgery
What is the symptomatic treatment for hyerpthyroid?
Oral or IV rehydration PRN, Beta-blocker: Propranolol, Atenolol, Metoprolol
Hyperthyroid treatment with Thionamides
Methimazole: Taper dose down, preferred
PTU: preferred in pregnant 1st trimester, causes agranulocytosis
Radioactive iodine treatment for hyerpthyroid
Treatment of choice*
PO single dose, causes fibrosis and destruction of thyroid over weeks, requires Levothyroxine for life
What is the treatment of choice for hyperthyroidism?
Radioactie iodine treatment
Surgical treatment for hyperthyroid
Indicated for non compliant patients, patients with large goiters, also need lifelong Levo
What occurs in people with untreated hyperthyroidism?
Thyroid storme
Thyroid storm can be brought on by what?
Major stress such as trauma, heart attack, or infection
Clinical presentation of thyroid storm
Fever, tachycardia, HTN, neurological and GI abnormalities
HTN can be followed by CHF with hypotension and shock
Is thyroid storm fatal?
If left untreated, yes
Treatment of thyroid storm
Antipyretics PRN, IV rehydration, IV Thiourea, administration of iodine compound PO (Lugol’s solution) one hour AFTER Thiourea, Glucocorticoids
What does the Lugol’s solution block?
Blocks release and conversion of T4/T3
Why are glucocorticoids given in thyroid storm treatment?
For adrenal insufficiency, will decrease the conversion of peripheral T4/T3
Thyrotoxicosis refers to what?
Clinical manifestations associated with serum levels of T4 or T3 that are excessive for the individual
Subacute thyroiditis is also known as what?
“De Quervain” or “granulomatous” thyroiditis. Its typically caused by various viral infections
What is the most common cause of hypothyroidism in developing countries?
Iodine deficiency
What is the most common cause of hypothyroidism in US?
Hashimotos
Who is more likely to be hypothyroid?
Elderly, F>M, caucasian>AA
Myexedema coma has what?
High mortality rate
Hypothyroid etiology
- Hashimotos (Autoimmune thyroiditis)
- Thyroidectomy
- Central hypothyroidism
Hypothyroidism symptoms
Fatigue, lethargy, depression , weakness, dyspnea on exertion, arthralgias/myalgias, muscle cramps, menorrhagia, constipation, HA, paresthesias, cold intolerance, infertility
PE findings of hypothyroidism
Dry skin, weight gain, thinning of hair, puffy face/eyelid, goiter, bradycardia, delayed reflex
Labs/diagnostics for hypothyroidism
TSH (best screening tool), FT4, T4/T3, thyroid antibodies, LDL triglycerides, sodium, glucose, anemia, BMP
TSH is hypothyroidism?
Elevated
FT4, T4 and T3 in hypothryoid
All low
LDL triglycerides in hypothyroidism?
Elevated
Sodium, glucose in hypothyroidism
Hyponatremia, hypoglycemia, decreased BMP
Treatment for hypothyroidism
Levothyroxine (synthroid): take with water in morning after overnight fasting, start low and titrate up with elderly
Which antibodies are elevated for hypothyroidism?
Elevated antithyroid peroxidase TPO Ab and antithyroglobulin antibodies TgAb
What invades the thyroid gland in Hashimotos?
B-lymphocytes invade it, also known as chronic lymphocytic thyroiditis
What is severe, life threatening hypothyroidism?
Myxedema comas
Si/sx of myxedema coma
Impaired cognition, confusion, severe hypothermia, hypoventilation, hyponatremia, hypoglycemia, hypotension, rhabdo and AKI can occur
Myxedema treatment
Large doses of Levo IV, hypothermic: warm with blankets, hypercapnia: intubate and assist mechanical ventilation, infections: treat aggressively, adrenal insufficiency: hydrocortisone
Abnormal findings on thyroid fxn tests that occur in setting of nonthyroidal illness, without thyroid gland dysfunction
Euthyroid sick syndrome
Lab results for euthyroid sick syndrome
TSH normal, NORMAL or low T4, T3, serum cortisol elevated, antibodies negative
Treat: underlying cause
Inflammation of the thyroid gland
Thyroiditis
Includes a group of individual disorders causing thyroidal inflammation but presenting in different ways
Thyroiditis
Treatment of thyroiditis
Symptomatic relief of thyroid pain and tenderness
What can occur in the recovery phase from thyroiditis?
43% hypothyroidism
32% hyperthyroidism
25% hyperthyroidism follow by hypothyroidism
What is the etiology of subacute lymphocytic thyroiditis/ silent thyroiditis/ painless thyroiditis
Often autoimmune related can occur after exposure to certain drugs, like interferon-alpha, interleukin-2, lithium and tyrosine kinase inhibitors
How do you decipher subacute lymphocytic thyroiditis/ silent thyroiditis/ painless thyroiditis from Graves disease?
There it little to no thyroid enlargement, no graves opthalmology
Post partum thyroiditis etiologies
2-13 mos postpartum, painless, usually transient. >80% will have antibodies. The hyperthyroid lasts a few weeks and most progress to hypothyroid which can last months. Recurrence rate high 70%
What percentage of people with subacute lymphocytic thyroiditis/ silent thyroiditis/ painless thyroiditis with have antibodies?
50%
What is another name of subacute granulomatous thyroiditis
De Quervains
Etiologies of De Quervains
Low grade fever, viral etiology: URI with extreme neck pain. Painful nodule, throat, dysphagia
Why is De Quervains often overlooked?
Symptoms mimic pharyngitis, must rule out infectious bacterial suppurative thyroiditis
Chronic lymphocytic thyroiditis is also called what?
Hashimotos Thyroiditis
What drugs can cause thyroiditis?
Amiodarone, Lithium, Phenytoin, Radioactive iodine
Amiodarone Thyroiditis
Type 1: active production of excessive hormones due to too much free iodine
Type 2: destructive thyroiditis which releases stored hormones
Thyroiditis treatment
Treat symptoms, treat with levo if in hypothyroid state, DO NOT treat with Thionamides
Epidemiology of thyroid cancers
1% of all endocrine cancers, death rate low, peak incidence 3rd and4th decade of life, papillary follicular, medullary, and anaplastic carcinomas
What are some risk factors for thyroid cancers?
Radiation exposure, MEN (medullary carcinoma), family hx, hashimotos? iodine deficiency? (follicular carcinoma), nodular dx <30year and >60 years age
Thyroid cancer si/sx
Painless, palpablenodule. Firm non mobile nodules suspicious for malignancy
Rapid growth: bad sign
Vocal cord paralysis, hoarse voice
What is a Firm cervical mass highly suggestive of ?
Regional lymph node and metastasis
What is the most common type of thyroid cancer?
Papillary: Psammoma bodies: cleaved nuclei
Papillary thyroid cancer
Multifocal, invades locally. Spread via lymphs and through the blood, SLOW growth
What type of thyroid cancer is more common in iodine deficient regions?
Follicular, spreads through the blood
Has the Hurthle cell
What does the Hurthle cell require?
Rare, considered a variant of follicular carcinoma that required aggressive surgery
Which type of thyroid cancer is involved with MEN 2A and 2B?
Medullary
Medullary thyroid cancer
Calcitonin is elevated, management is primarily surgical, high rate of recurrence
Poorly differentiated, aggressive, early metastasis to nodes and distant sites. Poor prognosis
Anaplastic thyroid cancer
Anaplastic thyroid cancer
Uncommon, inactivation of p53 gene, older patients with a rapidly enlarging mass
Thyroid cancer diagnostics
Ultrasound: can provide info for possible FNA
Diagnostic of choice: Fine needle aspiration
What labs can be used to diagnose thyroid cancer?
TSH, serum calcitonin and CEA, PCR germline mutation (medullary)
Thyroid radioiodine imaging: can provide hint whether malignant or not
CT or MRI without contrast: evaluates soft tissue extension of large or suspicious thyroid mass
Hot vs Cold thyroid
Used to describe findings on a radioactive iodine uptake scan
The hotter the nodule, the less likely its cancerous
Thyroid cancer treatment
Gold standard: Thyroidectomy
