Thyroid Flashcards
What is the function of the thyroid?
- metabolism
- regulate long bone growth
- brain development
Hormone overview for thyroid
TRH–>TSH–>T3/T4
Physiology of hormone release in the thyroid
hypothalamus releases TRH–>triggers anterior pituitary to release TSH–>triggers the thyroid to release thyroxine–>gets converted to T3/T4 in the tissue
Why iodine important to the thyroid
needed to produce T3 and T4
What is thyrotoxicosis
elevated unbound thyroid hormone circulating in the body
What is the #1 cause of hyperthyroidism in the US
Grave’s disease
Typical age of diagnosis of hyperthyroidism? gender?
occurs in women 20-40 years of age
What are the primary causes of hyperthyroidism
- Grave’s disease
- toxic multinodular goiter
- toxic nodular goiter
Symptoms of hyperthyroid
- irritability/nervousness/anxiety
- sweating
- fatigue
- muscle weakness
- palpitations
- increased bowel movements
- SOB
- heat intolerance
- menstrual irregulatities
Finding specific for Grave’s disease
- opthalmopathy/exophthalmos
- infiltrative dermopathy
- thyroid acropathy
- goiter with bruit
Physical exam findings for hyperthyroid. skin/nails HEENT cardiac neuro endocrine
skin/nails:
- pruritus
- moist skin
- thinning hair
- hyperpigmentation
- oncholysis
HEENT:
- lid lag
- exopthalmous
- goiter or nodules
Cardiac:
-tachycardia/afib
Neuro:
- fine tremor
- hyperreflexia
Endocrine:
-weight loss despite increased appetite
Labs in hyperthyroidism. TSH Free T4 Total T3 antibodies Serum cholesterol calcium
TSH- decreased T3/T4- increased antibodies will be present in Grave's disease serum cholesterol- decreased hypercalcemia
What imaging studies are done in hyperthyroid? what do they show?
Nuclear scintigraphy with radioactive iodine uptake
shows diffuse, increased uptake
Which causes of hyperthyroid present in the elderly
- toxic multinodular goiter
- toxic nodular goiter
What would a thyroid scan show with toxic nodular.multinodular goiter
irregular or diminished uptake
Treatment options for hyperthyroid
- symptomatic treatment
- antithyroid drugs (thionamides)
- radioactive iodine treatment
- surgery
What is the treatment of choice for hyperthyroid
radioactive iodine treatment
Symptomatic treatment for hyperthyroid
-rehydration
-beta blocker
propanolol
atenolol
metoprolol
Thionamides used for hyperthyroid
- Methimazole (preferred)
- PTU (pregnancy)
What is the end result of radioactive iodine treatment
permanent hypothyroid, must give levothyroxine
In what patients is surgery indicated for hyperthyroid
- children
- pts with large goiters
- non compliant patients
What is a thyroid storm
complication of untreated hyperthyroidism
What typically triggers a thyroid storm
major stressor
- trauma
- heart attack
- infection
Clinical presentation of thyroid storm
- fever
- tachycardia
- hypertension
- neurological and GI abnormalities
- delerium
- N/V/D
- heart failure
- pulmonary edema
How do you treat a thyroid storm
- antipyretics
- IV rehydration
- beta blocker
- IV thiourea
- Lugol’s solution 1 hr after thiourea
- gluccocorticoids
What is subacute thyroiditis
de Quervian thyroiditis
-typically caused by a viral infection
What is the #1 cause of hypothyroid in developing countries
iodine deficiency
What is the most common cause of hypothyroid in the US
Hashimoto
Causes of hypothyroid
- autoimmune thyroiditis (hashimoto’s)
- thyroidectomy
- central hypothyroidism
Symptoms of hypothyroidism
- fatigue/lethargy
- depression
- weakness
- arthralgia
- constipation
- headache
- paresthesias
- cold intolerance
- infertility
Exam findings for hypothyroidism
- dry skin
- weight gain
- thinning of hair
- puffy face/eye
- goiter
- bradycardia
- delayed reflex
Labs for Hashimoto’s
- TSH (elevated)
- T3/T4 (low)
- antibodies
- hyponatremia
- hypoglycemia
- anemia
- decrease basic metabolic rate
pathophys of chronic lymphocytic thyroiditis
invasion of B lymphocytes in the thyroid gland
Treatment of choice for hypothyroid
levothyroxine (T4)
Myxedema coma
severe hypothyroidism
Who is myxedema coma most often seen in
elderly that stop taking their medication
Signs of myxedema coma
- hypothermia
- hypoventilation
- hyponatremia
- hypoglycemia
- hypotension
- rhabdo/AKI
Treatment of myxedema coma
- high IV dose levothyroxine
- warm with blankets
- intubation
- treat infections
- hydrocortizone if adrenal insufficiency present
Euthyroid sick syndrome
abnormal finding on a thyroid function tests that occur in the setting of a nonthyroidal illness
Common illnesses that cause euthyroid sick syndrome
MI, DKA, CRF, cirrhosis
What are the TSH levels in euthyroid sick syndrome? T3/T4?
TSH is NORMAL
normal to low T3/T4
What levels are elevated in euthyroid sick syndrome
cortisol
What causes subacute lymphocytic thyroiditis
- autoimmune mediated
- exposure to certain medication (lithium, interleukin-2, interferon-alpha, tyrosine kinase inh)
What do most patients with post partum thyroiditis get
Hashimoto’s
Signs of subacute granulomatous thyroiditis
- low grade fever
- viral sx
- painful nodule
- dysphagia
What is chronic lymphocytic thyroiditis
Hashimoto’s thyroiditis
What drugs can cause thyroiditis
- amiodarone
- lithium
- phenytoin
- radioactive iodine
What two values are elevated in subactute granulomatous thyroiditis but not subactue lymphocytic thyroiditis
SED rate and CRP
Amiodarone thyroiditis type 1
active production of excessive hormones due to too much free iodine
Amiodarone thyroiditis type 2
destructive thyroiditis that releases stored hormones
How do you treat thyroiditis
- treat symptoms
- levothyroxine in hypo
- do not give thionamide if hyper*
Risk factors for thyroid cancer
- history of radiation exposure
- multiple endocrine neoplasia (MEN)
- family history
Four types of thyroid cancer
papillary, follicular, medullary, anaplastic
What is present in papillary thyroid cancer
Psammoma bodies- cleaved nuclei
What put a person at an increased risk for papillary thyroid cancer
Hashimoto’s
What is medullary thyroid cancer associated with
MEN 2A and 2B
Where is follicular thyroid cancer more common
iodine deficient regions
How does papillary thyroid cancer spread
lymphatic and hematogenously (bone, lung)
How does follicular thyroid cancer spread
hematogenously (bone,lung, CNS)
What are poor prognostic indicators for follicular thyroid cancer
- hurthle cell
- > 4cm
- > 50 y/o
- distant mets
- vascular invasion
What causes anaplastic thyroid cancer
inactivation of the p53 gene
Which thyroid cancer has the worse prognosis
anaplastic
What is the diagnostic tool of choice for thyroid cancer
fine needle aspiration
What labs are checked fro medullary thyroid cancer
- serum calcitonin and CEA
- PCR germline mutation
Hot vs cold. Which one is better
Hotter the better
Treatment of thyroid cancer
thyroidectomty
