Thyroid disorders - Endo Flashcards
Screening for Dysfunction
- Testing patients at risk of having thyroid disease who are presently not known to have thyroid disease
- Serum TSH first, then free T4 & T3 if needed
- [Normal TSH 0.05-5.0 mU/L]
- TSH normal -> no further testing
- TSH high -> free T4
- TSH low -> free T4 and T3
Hyperthyroidism Overactive Thyroid Gland
- Also called thyrotoxicosis
- Thyroid is making more thyroid hormones than the body needs
- Causes many bodily functions to speed up
- Affects about 1% of the U.S. population
- Suppresses TSH, so low TSH
Causes
- Graves’ disease – most common cause of hyperthyroidism in U.S.
- Thyroiditis
- Thyroid nodules
- Overmedicating with synthetic thyroid hormone
- Too much iodine intake
- Amiodarone, foods (seaweed, salt)
- Pituitary adenoma : rare
Hyperthyroidism: Signs and Symptoms By System
Cardiovascular:
- palpitations, tachycardia, new onset atrial fibrillation, PACs, CHF, SOB
Metabolic
-increased perspiration, heat intolerance, weight loss with increased appetite, deterioration glucose control, osteoporosis
GI/GU
-hyperdefecation, urinary frequency
Skin
-fine/oily hair, diaphoresis, flushing, goiter to neck
Reproductive
-oligomenorrhea, amenorrhea, gynecomastia, ED
Neuro
-anxiety, emotional lability, weakness, tremors, trouble sleeping, hyperreflexive
Graves’ Disease
- aka Toxic Diffuse Goiter
- Autoimmune disorder
- Immune system attacks own body by making an antibody called Thyroid Stimulating Immunoglobulin
- TSI attaches to thyroid follicular cells and mimics action of TSH
- Stimulates/Tricks thyroid into make too much thyroid hormone – T3 and T4, suppress TSH
Risk Factors
- Female gender 8:1
- Age<40 yo
- Personal history of other autoimmune diseases
- Tobacco abuse
- Family history
- Physical or emotional stress
- Pregnancy
Unique to Graves’
Graves’ ophthalmopathy ~30% will have, <5% severe i-nflammation, swelling, bulging of eyes -more often, more severe in smokers? -can occur late, lasts couple yrs
Graves’ dermopathy
- pretibial myxedema
- lumpy, reddish, thickening of skin to shins
- usually painless
Hyperthyroidism Diagnosis
- TSH low
- Free T4 high
- T3 high
-Thyrotropin-Receptor Antibodies, particularly TSI, present in 75-95% of pts with Graves’ Disease
Hyperthyroidism Treatment
Beta blockers
- First line to control adrenergic symptoms
- Non-selected Bb preferred such as propranolol
Iodides
- Blocks peripheral conversion of T4T3
- Inhibits thyroid hormone release
- Used in preparation for definitive treatment
Antithyroid drugs
- Suppresses hormone release
- Methimazole: drug of choice in nonpregnant patients
- Propylthiouracil (PTU): preferred for pregnant women
Radioactive iodine
- Treatment of choice for most Graves’ in U.S. – after sxs control
- Concentrates in thyroid gland, destroys thyroid tissue
- Cure rate near 80% after one single treatment
- Need to be on thyroid replacement because it causes hypothyroid
-Surgery - subtotal thyroidectomy
Thyroiditis
- Inflammation of thyroid that damages follicular cells resulting in unregulated release of T4 and T3
- Classic pattern is initial hyperthyroidism that usually lasts 1-2 months (until stores of T4 and T3 are depleted, unlike Graves’), followed by hypothyroidism before thyroid completely heals
- Categorize by painful vs painless
Painful
- Subacute thyroiditis
- Infectious
- Traumatic
- Radiation
Painless
- Hashimoto’s thyroiditis
- Painless /silent
- Postpartum
- Drug-induced
- Fibrous
Painful Thyroiditis
Subacute Thyroiditis
- Most common of painful types
- Also called subacute nonsuppurative thyroiditis or deQuervain’s thyroiditis
- Most commonly patients have had precedent (weeks) viral infection
- Usually no specific treatment – resolves on its own
Infectious Thyroiditis
- Acute or chronic
- Nonviral infection or abscess
- Think staph or strep
- Sudden onset neck pain, unilateral neck mass, fevers, chills, red hot, swollen
- Ultrasound can differentiate from subacute
- May need aspiration, drainage, abx therapy
Radiation Thyroiditis
- Occurs about 1% of people who undergo radioiodone treatment
- Pain and tenderness 5-10 days after treatment
- Radiation-induced injury and necrosis of follicular cells
- Symptoms are mild and transient
Trauma-Induced Thyroiditis
- Vigorous palpation during physical exam
- Manipulation during biopsy or surgery
- Trauma from MVC
- Symptoms are mild and transient
Painless Thyroiditis
Silent Thyroiditis
- Variant of Hashimoto’s
- Likely autoimmune mediated
- Mild hyperthyroidism, followed by mild hypothyroidism before recovery
- Short duration
- Little or no thyroid enlargement
- No Graves’ ophthalmopathy or pretibial myxedema
Post-Partum Thyroiditis
- Similar to painless
- Likely autoimmune mediated
- Occurs in women within 1 year of giving birth (or abortion)
- 8-10% of pregnancies
Drug-Induced Thyroiditis
- Interferon-alpha: HCV (Hepatitis C) patients, only one with true causal relationship
- Interleukin-2: cancer patients
- Amiodarone: contains 37% iodine, can cause hypo/hyperthyroidism, increased synthesis and/or excess release of thyroid hormones
- Lithium: increased incidence of hyperthyroidism
Fibrous Thyroiditis
- aka Riedel’s thyroiditis or invasive thyroiditis
- Extensive fibrosis, and macrophage/eosinophil infiltration of gland
- Hoarseness, dysphagia, hard and fixed goiter
- Most pts are euthyroid
- Dx by biopsy
- Tx: prednisone, surgery
Hypothyroidism = Underactive Thyroid Gland
- When thyroid gland doesn’t make enough thyroid hormones to meet body’s needs
- Causes many of our bodily functions to slow down
- Affects 4.6% of U.S. population
- Women»_space; men
- More common in those >60yo
Causes/Risk factors
- Hashimoto’s disease – most common cause in U.S.
- Thyroiditis – first hyperthyroid then hypothyroid
- Congenital hypothyroidism – if untreated leads to MR, FTT
- Surgical removal of part/all thyroid
- Radiation of thyroid – after radioactive iodine
- Some medications – amiodarone, interferon, lithium
- Too little iodine in diet – rare in developed countries
- Hypothalamic-Pituitary disease – hypopituitarism
Hashimoto’s Disease
- aka chronic lymphocytic thyroiditis or chronic autoimmune thyroiditis
- Most common inflammatory condition of thyroid
- Autoimmune condition characterized by infiltration of thyroid gland by lymphocytes
- Most common inflammatory condition of thyroid in U.S.
- 7:1 women, peak age 40-60 yo
- Symmetric, diffusely enlarged gland that is usually painless – goiter
- Anti-thyroid peroxidase antibodies hallmark
- Increased incidence of thyroid lymphoma and thyroid carcinomas, watch for fast growing nodules
Hypothyroidism - s/s
Skin
-cool, pale, dry, rough, coarse hair, brittle nails, myxedema in severe cases
Eyes
-periorbital edema, stare, protrusion of eyes, eom weakness
Hematologic
-normochromic normocytic anemia, increased risk of bleeding from hypocoagulable state - decrease in VW factor
GI
-constipation, decreased taste, gatric atrophy, celiac disease, weight gain, edema
Reproductive
-amenorrhea or menorrhagia, decrease fertility, decrease libido, ED, hypogonadism
MSK
-joint pains, aches, stiffness, hyperuricemia
Neuro
-fatigue, weakness, cold intolerance, AMS, hypothermia, slow movement/speech, depression, delayed DTRs
Cardiovascular
-decreased cardiac output, HR & contractility, SOB, decreased stamina, pericardial and pleural effusions, HTN, worsening HF or angina in patients with CHF
Metabolic
-HypoNa, increased Cr, increased lipids, decreased drug clearance, adrenal insuff
Diagnosis and Treatment of Hypothyroidism
- TSH high
- Free T4 = low
- T3 = nml to low
- Treatment revolves around exogenous replacement of synthetic thyroxine which is identical to T4 (i.e. levothyroxine)
- Dose chosen depends on many factors, generally initiate patient on low dose (25mcg) then have them come back for a recheck TSH (should come down) in 6-8 weeks, uptitrate as needed
- Upper limit of TSH is 5.0 – sxs are not dependent on TSH level, can tx based on sxs, if has sxs and not a super high TSH treat
- Monitor for symptoms of hyperthyroidism after replacement– rarely some patients misuse their thyroxine by taking over the prescribed dose to facilitate weight loss
Thyroid Nodules
- Palpable swelling of thyroid gland with otherwise normal appearance
- Palpable nodules ~5% of population: May be much more common 20-60%
- Majority asymptomatic
- 4:1 women, more common where iodine deficiency exists
- Most euthyroid, rare hyperthyroid
- Various types
- Need to work up for cancer
- 5% malignant
