Thyroid Disease Flashcards
Presenting symptoms of hyperthyroidism
progressive nervousness, palpitations, weight loss, irritability, fine resting tremor, dyspnea on exertion, concentration difficulties
Physical exam findings of hyperthyroidism
fine resting tremor, rapid pulse, elevated BP (more in systolic so greater pulse pressure), atrial fib
acute hypermetabolic state associated with sudden release of large amounts of thyroid hormone into circulation
thyroid storm
Symptoms of thyroid storm
autonomic instability, confusion, psychosis, restlessness, dysrhythmias,
pathophysiology of Graves dx
autoimmuno disorder caused by immunoglobulins (IgG) antibodies that bind to TSH receptors initiating the production and release of thyroid hormone
common, distinct feature of Graves dx
exophthalmos
second most common cause of hyperthyroidism
autonomous thyroid nodule that secretes thyroxine (ignores TSH)
other causes of hyperthyroidism besides Graves and autonomous thyroid nodule
iatrogenic hyperthyroidism (overuse of thyroxine supplement), thyroditis (acute stages)
Lab values in hyperthyroidism
elevated thyroxine (free T4) and low TSH
Once hyperthyroidism is established with lab values, what test to do next?
radionucleotide imaging (direct scan of gland) with tech99 or iodine123
How to Graves appear on radionucleotide scan
diffuse hyperactivity with large amounts of uptake
How does thyroiditis appear on radionucleotide scan
patchy uptake with overall reduced activity (reflects release of hormone rather than overproduction of it)
How to treat Graves
radioactive iodine
Who shouldn’t get radioactive iodine
pregnant mothers and children
What are alternatives to radioactive iodine?
anti-thyroid meds like PTU, methimazole, carbimazole (inhibit organification of iodine and prevents conversion of T4 into T3; the more active form)
ESP EFFECTIVE IN ADOLESCENTS WITH GRAVES
Harmful side effects of antithyroid drugs
hepatotoxicity (PTU; blackbox warning), agranulocytosis
If iodine/antithyroid meds aren’t working for Graves?
SURGERY; can also do this if huge goiter is compressing nearby structures
Symptoms of hypothyroidism
weight gain, cold intolerance, hair loss, lethargy, dry skin, slowed mentation, constipation, depressed
What can hypothyroidism be confused with in elderly patients?
Alzheimers
Most common cause of noniatrogenic hypothyroidism in the US
hashimoto’s thyroiditis
Iatrogenic/other causes of hypothyroidism
post-Graves disease thyroid ablation and surgical removal of thyroid gland, secondary to hypothalamus/pituitary dysfunction (i.e. intracranial radiation or removal of pituitary adenoma)
Primary hypothyroidism vs secondary hypothyroidism on lab values
Primary - elevated TSH, low T4 (dysfunction with gland)
Secondary - low TSH, low T4 (dysfunction in HPA axis)
Once primary hypothyroidism is diagnosed, what workup is needed next?
NOTHING! esp if thyroid gland is normal on physical….just start supplementing with thyroid
Once secondary hypothyroidism is diagnosed, what workup is needed next?
need to determine if hypothalamus or pituitary is the problem
IV TRH test! stimulates pituitary to release TSH. If pituitary releases TSH, then hypothalamus done fucked up. If there is no increase in TSH, the pituitary done fucked up
Starting dose for thyroid replacement
25-50 ug daily then increase to 25 every 3-4 weeks until optimal dose is reached
How to determine is thyroid replacement dose is appropriate?
Serial TSH checks! Check 4-6 weeks after adjustment has been made
Check for TSH between 0.3 (too much thyroid) and 5 (too little thyroid/ bad med adherence)
Incidence of malignancy in incidental finding of thyroid nodule
5-6% SO WORK THESE UP
Risk factors for thyroid cancer
family history, dysphagia, SOB, cervical lymphadenopathy, new onset hoarse voice
How to evaluate a thyroid nodule
Ultrasound for size, character (cystic v solid), presence of other nodules
thyroid function tests (measure TSH)
Prognosis of functional adenoma
rarely malignant
When to biopsy a nodule
when nodule measure greater than 1cm in person with elevated or normal TSH
do this with FNA
Types of thyroid carcinomas and how to diagnose
papillary, medullary, anaplastic thyroid carcinomas
dx by FNA
Treatment for thyroid cancer
thyroidectomy followed by radioactive ablation
In pregnant patient, when to use PTU vs methimazole
if they aren’t pregnant and can’t do radioactive iodine METHIMAZOLE IS FIRST LINE
but if they are preggo
PTU 1st trimester
methimazole 2nd and 3rd
