Thyroid Disease Flashcards
What do the follicular cells of the thyroid gland produce?
- thyroid hormone
What do the C cells or parafollicular cells of the thyroid gland produce?
- calcitonin
What is the function of the thyroid gland?
- produce thyroid hormones that control the rates of metabolism throughout the body
In the ______ tissues, ____ is converted to _____.
- body
- T4
- T3
Between T4 & T3, which has the greater metabolic effect/is stronger, more potent?
- T3
What is essential to maintain euthyroid function?
- iodine
How is the thyroid gland regulated?
- neg. feedback
How is thyroid function assessed?
LABS:
- TSH (thyroid stimulating hormone)
- T4 (thyroxine)
- T3 (triiodothyronine)
- anti-thyroid antibodies
- anti-thyroid peroxidase (antiTPO)
What is goiter?
- increased size of thyroid
- usually palpable
When does goiter occur?
- hypothyroid
- euthyroid
- hyperthyroid
What causes a goiter?
- hypertrophy of tissue from thyroid hormone output malfunction
What complications can occur as a result of goiter?
- compression of esophagus, trachea, jugular v, and superior vena cava
Define Pemberton’s Sign
- facial erythema and jugular v. distention that progresses to cyanosis and facial erythema when both arms are raised over the head
What is the most preventable cause of mental retardation?
- congenital hypothyroidism
What is the etiology of congenital hypothyroidism?
- thyroid gland dysgenesis or agenesis
- inborn error of thyroid hormone synthesis
What do the S&S of congenital hypothyroidism result in?
- cretinism
What are the S&S of congenital hypothyroidism?
- mental retardation
- growth impairment (most noticeable)
- poor psychomotor development
- permanent neurologic damage (occurs if tx is delayed)
- infants may appear normal at first d/t maternal hormones
What is the treatment/prevention of congenital hypothyroidism?
- screening at birth
- tx with hormone supplement
What are the types of hypothyroidism?
- primary
- transient
- secondary/central
What are the etiologies of primary hypothyroidism?
- autoimmune
- drugs
- congenital
- iodine deficiency
- acquired (s/p thyroidectomy)
What are the etiologies of transient hypothyroidism?
- subacute thyroiditis
- withdrawal of thyroxine tx
What are the etiologies of secondary/central hypothyroidism?
- hypopituitarism
- hypothalamic disease
What is the most common form of thyroiditis & most common cause of thyroid disease in the US?
- Hashimoto’s thyroiditis
What is the cause of Hashimoto’s thyroiditis?
- autoimmune
- lymphocytic infiltration of the thyroid
What are the symptoms of hypothyroidism?
- wt gain
- fatigue/lethargy
- depression
- constipation
- dry skin
- cold intolerance
What are the signs of hypothyroidism?
- bradycardia
- thin brittle nails
- thinning hair
- thinning lateral 1/2 eyebrows
- non-pitting pretibial edema
- puffy face & eyelids
What is the name for the constellation of hypothyroid symptoms?
- myxedema
What are the S&S unique to Hashimoto’s?
- initial transient hyperthyroidism d/t release of T3/T4 from damaged cells
- eventually develops into a hypothyroid state d/t destruction of gland
- non-tender goiter initially then common S&S of hypothyroidism
What labs should be drawn for hypothyroidism?
- serum TSH
- FT4 (free T4)
- anti-thyroid antibodies
- anti-thyroid peroxidase (antiTPO)
What will the TSH level be in primary hypothyroidism?
- elevated
What will the FT4 level be hypothyroidism?
- low or low-normal
What are the anti-thyroid antibody levels in hypothyrodism?
- high
What other lab abnormalities are common in chronic hypothyroidism?
- increased LDL, cholesterol, triglycerides, liver enzymes, & creatine kinase
- hyponatremia
- hypoglycemia
- anemia
What are the lab values for subclinical hypothyroidism?
- normal FT4
- mildly elevated TSH
What is the tx for subtle symptoms of subclinical hypothyroidism?
- thyroid replacement
What is the tx for asymptomatic subclinical hypothyroidism?
- close monitoring
T/F: Imaging is always necessary for hypothyroidism dx.
- false
When is imaging necessary for hypothyroidism?
- asymmetric goiter = US
- solitary lesion/focal nodule = FNA (fine needle aspiration)
What are complications of hypothyroidism?
- myxedma crisis (rare)
- infertility
- miscarriages
- sellar enlargement/TSH secreting tumors
- cardiac complications
- megacolon
- increased risk of bacterial PNA
What is the tx for hypothyroidism?
- daily levothyroxine
When should labs be redrawn s/p hypothyroid tx?
- 6wks
How fast are TSH response?
- gradual
How are levothyroxine doses adjusted?
- small increments (12.5-25mcg/d)
What is the starting dose in elderly patients?
- low (12.5-25mcg qd)
What is the risk of untreated preggers with hypothyroidism?
- adverse fetal neural development
- preterm labor
What is the dose of levothyroxine in preggers?
- increased by 50%
Define myxedema crisis
- severe, life-threatening hypothyroidism
What pt pop is myxedema crisis seen in?
- elderly women who have had a stroke or stopped thyroid replacement
What causes myxedema crisis?
- underlying infx
- cold exposure
- drug use
What is the tx goal of myxedema crisis?
- rapid thyroid hormone replacement
- supportive therapy to correct other metabolic conditions
Define hyperthyroidism
- overactive thyroid making too much thyroid hormone
What are the causes of hyperthyroidism?
- primary
- transient
- secondary
What are the etiologies of primary hyperthyroidism?
- graves
- toxic multinodular goiter or toxic adenoma
- struma ovarii
- drugs
What are the etiologies of transient hyperthyroidism?
- subacute thyroiditis, Hashimotos
- thyroid destruction
- thyrotoxicosis factita
What are the etiologies of secondary hyperthyroidism?
- TSH secreting pituitary adenoma
- thyroid hormone resistance syndrome
- molar pregnancy
- gestational thyrotoxicosis
- metastatic follicular thyroid cancer
Define Graves Disease
- autoimmune disorder affecting the thyroid gland
- characterized by an increase in synthesis and release of thyroid hormone
What is the most common cause of hyperthyroidism?
- Graves
What are the risk factors of Graves?
- high iodine intake as well as medication use
- genetic/family hx
What is the pathogenesis of Graves?
- antibodies to the thyroid gland’s TSH receptors
Define toxic single/multinodular goiter?
- nodules that produce thyroid hormone w/o the TSH receptor stimulation
What are the types of subacute thyroiditis?
- granulomatous thyroiditis (de Quervains or painful)
- lymphocytic thyroiditis (painless or silent)
Define granulomatous thyroiditis
- initial inflam causes thyroid follicle destruction and release of thyroid hormones followed by hypothyroidism then euthyroid
Define lymphocytic thyroditiis
- brief thyrotoxic state followed by hypothyroisim then resolution
What is the pt pop of lymphocytic thyroiditis?
- postpartum
What are the etiologies of hyperthyroidism?
- ectopic thyroid hormone production
- pituitary tumor
- iodine-induced hyperthyroidism
- amiodarone-induced thyrotoxicosis
What are the symptoms of hyperthyroidism?
- hyperactivity/irritability/dysphoric, anxiety
- heat intolerance & sweating
- palpitations
- fatigue & weakness
- wt loss w/ increased appetite
- diarrhea
- polyuria
- oligomennorhea, loss of libido
- insomnia, impaired concentration
What are the signs of hyperthyroidism?
- tachycardia, atrial fib in elderly
- tremor
- goiter
- warm. moist skin
What are signs specific to Graves?
- diffusely enlarged thyroid
- graves opthalmopathy
- thyroid dermopathy (pretibial myxedema)
What are the lab findings of Graves?
- low TSH
- elevated FT4
- (+) anti-thyroid & anti-thyroid peroxidase Abs
What imaging should be done for Graves?
- thyroid US
- thyroid scan (RAI uptake)
- MRI & CT scan for graves opthalmopathy
- EKG (not diagnostic)
What is the tx for Graves?
- symptomatic
- reduce T4 production via RAI, ATD, iodinated contrast agents, surgery
- beta blockers
When is RAI contraindicated?
- preggers
What are the ATD drugs used to tx Graves/hyperthyroidism?
- methimazole
- propylthiouracil (PTU)
How is iodinated contrast agents a tx for hyperthyroidism?
- temporary tx for thyrotoxicosis of any cause
- not used for definitive tx or long term
Who is treated with surgery for hyperthyroidism?
- pts who fail rx & RAI
- large goiters causing difficulty swallowing or airway compromise
What are potential complications of thyroidectomy?
- recurrent laryngeal n. paralysis
- hypoparathyroidism
What is the tx for single toxic adenoma?
- RAI ablation
What is the tx for toxic multinodular goiter?
- surgery
What is the tx for lymphocytic thyroiditis (painless, autoimmune)?
- symptomatic w/ beta blocker
What is the tx for De Quervains thyroiditis (painful, s/p virus)?
- short course NSAIDs or steroids
- ATD are ineffective
What are the S&S of thyroid storm?
- marked delirium
- severe tachycardia
- vomiting
- diarrhea
- dehydration
- very high fever
What is the tx of thyroid storm?
- induce euthyroid state (ATD, ipodate sodium, iodide, propranolol, & hyrdocortisone) followed by RAI or surgery
What does non-toxic mean in relation to thyroid disorder?
- normal hormone levels
What are the S&S of non-toxic thyroid adenomas & multinodular goiters?
- large nodule can cause discomfort, hoarsness, & dysphagia
- Pemberton sign
- most small are asymptomatic
What do all nodules & goiters require?
- labs & initial diagnostic imaging
What imaging is obtained for nodules/goiter?
- US
- RAI scan
- CT
- FNA bx
What is the best method to assess a nodule/goiter for malignancy?
- FNA bx w/ US guidance
What is the tx for non-toxic thyroid adenomas & multinodular goiters?
- monitoring w/ regular periodic palpation & US q6m
- rebx if growth occurs
- levothyroxine suppression therapy (>2cm nodules)
- surgery
What is the most common malignancy of the endocrine system?
- thyroid CA
What are the types of thyroid CA?
- papillary
- follicular
- medullary
- anaplastic
- other
Describe papillary thyroid CA
- most common
- least aggressive
What is the most aggressive type of thyroid CA?
- anaplastic
What are the S&S of thyroid CA?
- palpable
- firm
- non-tender
- fixed
- large
What is the definitive diagnostic test of choice for thyroid CA?
- FNA bx w/ cytology
What are the TFT (thyroid function test) for thyroid CA?
- generally normal
What (& why) imaging is done for thyroid CA?
- US: helps localize, measure, & asses for metastaitc dz
- RAI: used s/p thyroidectomy
- CT/MRI/PET: locates metastasis
What is the tx for thyroid CA?
- surgery
- RAI (131 I)
- radiation
- levothyroxine s/p thyroidectomy
What are the complications of thyroid CA?
- metastasis to lungs, bone, brain, adrenals, or LN
What are the complications of thyroid CA secondary to surgery?
- hypothyroidism
- hypoparathyroidism
- vocal cord paralysis
