Thyroid Disorders

Question 1

Hyperthyroidism: definition, etiology, s/sxs, & PE

Answer 1

• Definition: excess thyroid hormone synthesis & secretion by the thyroid gland. Thyrotoxicosis is the clinical effect experienced d/t an excess of thyroid hormones in the blood stream
• Etiology:
  
  • Grave’s (#1), iatrogenic thyrotoxicosis, thyroiditis, toxic multinodular goiter, toxic adenoma, TSH-secreting pituitary adenoma, amiodarone, ingestion of thyroid hormone
• Women > men
• S/sxs:
  
  • hyperactivity: anxiety, nervousness, irritability
  • Heat intolerance & sweating
  • fatigue & weakness
  • Weight loss despite increased appetite
  • hyperdefecation, polyuria
  • Oligomenorrhea
  • loss of libido
• Pe:
  
  • **Increased metaboli rate
    
    • tachycardia, palpitations
    • Fine tremor
    • Goiter, warm moist skin
    • muscle weakness, proximal myopathy, eyelid retraction, lid lag or stare

Question 2

Hyperthyroidism: Dx & Tx

Answer 2

• Dx:TSH: good initial screening test, low TSH, high Free T4
  
  • Free T4: helps to evaluate low TSH
  • total T3: detection of T3 thyrotoxicosis
  • Thyroid uptake & scan: can help distinguish b/w causes of thyrotoxicosis contraindicated in preggos/breastfeeding/amiodarone
  • thyroid U/S: used in preggos, evaluation of palpated nodule & to dx amiodarone-induced thyrotoxicosis
• Tx:
  
  • Antithyroid drugs: used in those with higher remission likelihood (women, mild dx, small thyroid glands, negative-low TSH-R ab) b/c only 30% of cases end up in remission:
    
    • Methimazole (1st line, no in 1st trimester preggos)
    • Propylthiouracil (2nd line, warning: hepatic necrosis); follow with TSH AND Free T3 (TSH is a poor response indicator early in tx)
    • 131 Iodine Ablation:avoid in Smokers (TED), no pregnancies x 6 mo post tx, should control comorbidities prior to tx
    • Surgery (Total thyroidectomy): best if done by a surgeon who does this a lot (in order to avoid hypoparathyroidism and laryngeal nerve damage), decreases progression of Grave’s orbitopathy, Do not use in 1st or 3rd trimester preggos

Question 3

Grave’s Disease

Answer 3

MCC of hyperthyroidism in the US

• Pathophys: autoimmune disease in which TSH-R ab target and STIMULATE the TSH-R on the thyroid gland → increased in thyroid hormone production → hyperthyroidism
• S/sxs:
  
  • s/sxs of hyperthyroidism
    
    • Graves Orbitopathy: proptosis, exophthalmos, lid lag, diplopia
    • Graves dermopathy: pretibial myxedema (swollen red or brown patches with non-pitting edema)
• PE:
  
  • Diffusely enlarged but non-tender goiter/thyroid
  • Thyroid Bruit
• Dx:
  
  • Decreased TSH, Increased T4
  • TSH-Receptor Ab: positive
    
    • Thyrotropin binding inhibitor immunoglobulin (TBII): positive
    • Thyroid stimulating immunoglobulin (TSI): positive
  • Thyroid Uptake & Scan: diffuse iodine uptake that is HIGH
• Tx:
  
  • Radioactive iodine (131Iodine Ablation): MOST COMMON
  • Antithyroid drugs: Methimazole or Propylthiouracil
  • Surgery: total thyroidectomy
  • beta blockers to alleviate tremor: Propranolol
  • Smoking cessation (tobacco worsens TED: thyroid eye disease)

Question 4

Toxic Multinodular Goiter

Answer 4

• Definition:
  
  • multiple nodules on the thyroid gland that are hyperfunctioning & autonomous
• S/sxs:
  
  • Compressive sxs:
    
    • dyspnea, dysphagia, stridor, hoarseness
• Dx:
  
  • Primary hyperthyroidism: low TSH, increased free T4
  • Thyroid Uptake & Scan: high iodine uptake in multiple nodules
• Tx:
  
  • 131I (iodine) ablation or surgery (total Thyroidectomy): may need to be treated with ATD prior to the procedure
  • certain pts can be treated with ATD (low dose) in the long-term

Question 5

Toxic Adenoma

Answer 5

• Definition:
  
  • single nodule on the thyroid gland that is hyperfunctioning & autonomous
  • *note: toxic = sxs of thyrotoxicosis
    
    • non-toxic = asymptomatic
• S/sxs:
  
  • compressive sxs:
    
    • dyspnea, dysphagia, stridor, hoarseness
• PE:
  
  • single, palpable thyroid nodule
• Dx:
  
  • primary hyperthyroidism: low TSH, high free T4
  • thyroid uptake & scan:
    
    • HIGH iodine uptake in a single thyroid nodule
• Tx:
  
  • 131I (iodine) ablation or surgery (total Thyroidectomy): may need to be treated with ATD prior to the procedure
  • certain pts can be tx with ATD (low dose) in the long-term

Question 6

Thyroid Storm (Thyrotoxic Crisis)

Answer 6

• Definition:
  
  • acute exacerbation of hyperthyroidism that is life-threatening and rare
• Etiology:
  
  • precipitated by illness, inx or surgery. usually associated with Graves, but sometimes toxic multinodular goiter
• S/sxs:
  
  • Severe tremor
  • Hyperpyrexia (104-106F)
  • palpitations & tachycardia
  • n/v, jaundice (d/t acute liver failure)
  • CNS dysfunction: anxiety, delirium, AMS, coma
  • resp failure
• Dx:
  
  • Clinical Diagnosis
    
    • with labs used to support hyperthyroidism
    • Labs: undetectable TSH, markedly elevated free T4 & T3 +/- TSH-R Ab elevation
  • Scoring system: see other flashcard
• Tx:
  
  • Endocrine emergency. Results in death if untreated (Mortality is 10%)
  • IV fluids
  • Propranolol
    
    • (reduce tachycardia & adrenergic sxs → tremor)
  • Anti-Thyroid Med (Propylthiouracil):
    
    • block synthesis of T3 & Y +T4
  • IV glucocorticoids:
    
    • reduced conversion of T4 to T3
  • Oral or IV sodium iodine

Question 7

Clinical Scoring System of Thyroid Storm (Thyrotoxicosis)

Answer 7

• Factors:
  
  • temperature, CNS dysfunction, GI & hepatic dysfunction, precipitant hx, heart rate, heart failure, AFib
• Score > 45 = highly supports dx of thyroid storm

Question 8

Hypothyroidism: Definition, etiology, s/sxs, PE

Answer 8

• Definition: decreased thyroid hormone synthesis & secretion by the thyroid gland
• Etiology:
  
  • Hashimoto’s, iodine deficiency = MCC in the world,medications (amiodarone, lithium, IFN, IL-2, iodinated IV contrast), post-ablative (131iodine)
  • Women > men
• S/sxs:dry skin, hair loss
  
  • Cold intolerance
  • Weight gain with poor appetite
  • hoarse voice, difficulty concentrating & poor memory
  • weakness & fatigue
  • myopathy, paresthesias, dyspnea, menorrhagia
• PE:
  
  • **Decreased metabolic rate
  • dry, thick skin with cool peripheral extremities
  • Myxedema: non-pitting edema on periorbital, dorsum of hands & feet
  • diffuse alopecia
  • Bradycardia, narrow pulse pressure, prolonged PR on EKG
  • Woltman’s sign: delayed tendon reflex relaxation
  • carpal tunnel syndrome
  • Galactorrhea

Question 9

Hypothyroidism: Dx & Tx

Answer 9

• Dx:
  
  • TSH = best thyroid function screening test, High TSH
  • Low Free T4
  • Free T3: order if euthyroid sick syndrome, thyroid hormone resistance or hypothalamic-pituitary disease suspicion
  • *Overt hypothyroidism: TSH > 10 & subnormal T4
  • Thyroid US = NOT useful if there aren’t any palpable changes on neck changes
• Tx:
  
  • neonatal screening→ helps to identify early congenital hypothyroidism
  • Levothyroxine
    *

Question 10

When to refer to endo in hypothyroidism

Answer 10

Child/infants, pts with difficult to maintain euthyroid state, pregnancy, questions about titration in CV disease, suspect med cause (amiodarone), presence of goiter/nodule, concurrent endocrine abnormalities, unusual constellation of thyroid function tests, unusual causes of hypothyroid, myxedema coma

Question 11

Hashimoto’s Thyroiditis

Answer 11

• aka Autoimmune Lymphocytic Thyroiditis
• Definition:
  
  • autoimmune lymphocytic infiltration of the thyroid → atrophy of thyroid follicles & fibrosis. 90% of thyroid gland gets destroyed before overtly become hypothyroid
• Triggers:
  
  • pregnancy, radiation exposure (external beam radiation, nuclear disasters), medications
  • Most common cause of hypothyroidism in the US. Women > men
• S/sxs:
  
  • s/sxs of hypothyroidism
• PE:
  
  • thyroid gland may be normal or atrophic/hypertrophic
  • bradycardia
  • loss of outer third of eyebrow
  • myxedema
• Dx:
  
  • Increased TSH + decreased Free T4
  • Thyroid Peroxidase (TPO) Ab: Positive (90%)
    
    • Anti-thyroglobulin Ab: positive
  • Thyroid US: heterogeneous echotexture “ patchwork quilt”
    
    • pseudonodules, septations, mildly enlarged anterior cervical lymph nodes
  • Thyroid Uptake & Scan: diffusely decreased iodine uptake
• Tx:
  
  • Levothyroxine = first line tx
    
    • Synthetic T4, SEs = osteoporosis & CV effects
  • Monitor TSH levels at 6 week intervals when initiating or changing dose

Question 12

Euthyroid Sick Syndrome

Answer 12

• Definition:
  
  • abnormal thyroid tests seen in pts with normal thyroid function → often due to severe nonthyroidal disease states (sepsis, cardiac malignancies) as a normal protective response
• Pathophys:
  
  • severe illness decreases peripheral conversion of T4 to T3
• Dx:
  
  • range of TSH & free t4 values depending on severity & timeline of the illness (at sickest, low TSH, T4, T3)
• Tx:
  
  • endocrine consult
  • tx the underlying disease state
  • *Starting levothyroxine is unnecessary and can be harmful in some pts

Question 13

Cretinism

Answer 13

• Definition:
  
  • untreated congenital hypothyroidism
• Etiology:
  
  • lack of maternal iodine during fetal development in developing countries, dysgenesis of the thyroid gland, acquired (TSH-R Ab passed across placenta)
• S/sxs:
  
  • developmental delays
  • short stature
  • hypothyroid sxs
  • goiter sxs: hoarseness, dyspnea
• PE:
  
  • coarse facial features, macroglossia, umbilical hernia
  • hypotonia (decreased DTRs)
  • jaundice, feeding problems
• Dx:
  
  • TSH = increased
  • T4/T3 = decreased
• Tx:
  
  • Levothyroxine (synthetic T4)

Question 14

Riedel Thyroiditis

Answer 14

• Definition: rare chronic autoimmune thyroiditis characterized by dense fibrosis that invades the thyroid & adjacent neck structures
• S/sxs:
  
  • rock hard, nontender, rapidly growing enlarged thyroid (similar to thyroid malignancy)
  • compressive sxs: neck tightness, hoarseness, dyspnea, choking, dysphagia
• Dx:
  
  • IgG 4 serum levels
  • open thyroid biopsy: dense fibrosis
• Tx:
  
  • Surgery: to reduce compression

Question 15

Myxedema coma

Answer 15

• Definition:
  
  • rare, extreme form of hypothyroidism with a high mortality rate
  • MCC in elder women with long-standing hypothyroidism in winter
• Precipitating Factors:
  
  • HF, PNA, pulm edema, pleural effusions, ileus, excessive fluid admin
• S/sxs:
  
  • coma: progressive weakness, stupor, hypothermia, hypoventilation, hyponatremia
  • Myxedema
• PE:
  
  • bradycardia
  • hypotension
  • Hypothermia (low as 75F)
  • hoarse voice & macroglossia
  • slowed reflexes, ileus, pale & dry cool skin
  • Sallow: yellow skin coloring (decreased carotene → vitamin A)
• Dx:
  
  • clinical diagnosis: labs to support
    
    • TSH: elevated
    • Free T4: low +/- positive thyroid peroxidase ab
    • elevated total cholesterol & LDL
• Tx:
  
  • Endocrine Emergency. Death will occur if untreated (20-40% risk)
  • supportive: airway, rewarming
  • IV levothyroxine +/- T3 supplementation
  • IV glucocorticoids

Question 16

Define Myxedema

Answer 16

boggy or puffy non-pitting edema seen periorbitally on dorsa of hands/feet & in the supraclavicular fossa

Question 17

Thyroiditis Definition

Answer 17

• inflammation of the thyroid gland → group of disorders that cause thyroidal inflammation but they present differently

Question 18

Postpartum Thyroiditis

Answer 18

Occurs 2-12 months after giving birth

• Pathophys:
  
  • immune system is depressed during pregnancy → after birth immune system becomes more active and might attack the thyroid
  • hyperthyroid phase 5-7 months after birth followed by a normal thyroid funx

Question 19

Subacute Thyroiditis

Answer 19

• aka Quervain’s Thyroiditis
• Definition:
  
  • thyroiditis occurring several weeks after a URI (coxsackie, mumps, influenza, adenovirus)
  • MCC of painful thyroid;women > men
• Phases:
  
  • hyperthyroid → euthyroid → hypothyroid → recovery
• Pathophys;
  
  • Destruction of thyroid follicles leads to transient & acute release of thyroid hormone → hyperthyroid. Followed by a period of transient hypothyroidism as the damaged follicles get repaired.
• S/sxs:
  
  • following sxs like: fever, myalgia, pharyngitis
• PE:
  
  • inflamed, painful thyroid, worse with head movement and swallowing, may radiate to jaw or ear
• Dx:
  
  • ESR: high (>50 mm/h)
  • thyroid ab: negative
  • hyperthyroid labs (in early disease): low TSH, increased free T3
  • thyroid uptake & scan: diffuse decreased iodine uptake
• Tx:
  
  • Thyroid fnx usually normalizes within 4-6 months but 15% never regain normal function
  • supportive care: self-limiting in 95%
  • NSAIDs or Aspirin for pain & inflammation

Question 20

Suppurative Thyroiditis

Answer 20

• Definition: bacterial infection of the thyroid gland Staph aureus = most common
  
  • rare
• S/sxs:
  
  • painful thyroid gland
    
    • acute onset with neck pain & tenderness, IMPROVES with neck flexion
  • overlying erythema to the skin
  • fever, chills, pharyngitis
• Dx:
  
  • leukocytosis
  • high ESR fine needle aspiration with gram stain & cx
• Tx:
  
  • abx
  • surgical drainage if fluctuant

Question 21

Drug-Induced Thyroiditis

Answer 21

• Thyroiditis caused by use of certain drugs:
  
  • Antithyroid meds: methimazole and propylthiouracil, lithium, amiodarone, interferon alpha, tyrosine kinase inhibitors
• Dx:
  
  • TSH should be checked Q6-12 months
  • usually causes hypothyroidism , high TSH, low T4/T3
• Tx:
  
  • d/c the offending drug if possible
  • T4 therapy given right away

Question 22

Thyroid Cancer: Risks, Types, Epidemiology, S/sxs

Answer 22

• Risks:
  
  • Prior radiation (head or neck)
  • family hx of thyroid cancer
  • > 65yo or < 20 yo
  • rapid growth of thyroid
• Types:
  
  • Papillary carcinoma (80%): common after radiation exposure, least aggressive Papillary is Popular
  • Follicular Carcinoma (12%): occurs with iodine deficiency, distant METS (follicular travels FAR in the body), more common in older adults
  • Medullary (4%): may be sporadic (usually unilateral); often familial; Calcitonin = a marker of the disease
  • Anaplastic (2%): most aggressive, no effective therapy exists and is generally fatal (~80% within 1 year of dx)
• Epidemiology:
  
  • 8th most common type of cancer, increased prevalence
• S/sxs:
  
  • rapid growth of anterior or lateral neck mass
  • nodule fixed &/or firm to palpation
  • unilateral cervical lymphadenopathy
  • newly hoarse voice or vocal cord paralysis
  • new dysphagia

Question 23

Thyroid Cancer: Dx & Tx

Answer 23

• Dx:
  
  • U/S =1st imaging choice
    
    • suspicious features:
      
      • hypoechoic, microcalcifications, taller than wide, lateral neck lymph node suspicious
  • US guided fine needle Biopsy (FNB):
    
    • **if nodule > 1cm or high-risk feature
      
      • benefits: direct visualization of nodule & needle within the target, assessment of vascularity, avoid other neck structures
      • Risks: FB sensation, pain/bruising at biopsy site, insufficient result, hematoma, cyst, thyroiditis
• Tx:
  
  • Benign nodule:
    
    • repeat thyroid US in 1 year (note: 15-20% of nodules will grow) → if nodule significantly larger then refer for repeat biopsy
    • if < 50% change in volume then US in 1-2 years
      
      • do NOT use levothyroxine
• Atypical cells of undetermined significance: refer to endocrinologist for repeat biopsy or markers, 5-10% risk of malignancy
  
  • suspicion for malignancy> refer to endo or thyroid surgeon
• Thyroid cancer: refer to thyroid surgery & endocrinologist; order neck US with attention to lateral neck is important before thyroid surgery (to identify concerning lymph nodes - metastasis), may get CT/MRI