Thyroid Disorders Flashcards

Question 1

Q

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

Answer

A

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

Q

Hyperthyroidism: Dx & Tx

Answer

A

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

Q

Grave’s Disease

Answer

A

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

Q

Toxic Multinodular Goiter

Answer

A

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

Q

Toxic Adenoma

Answer

A

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

Q

Thyroid Storm (Thyrotoxic Crisis)

Answer

A

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

Q

Clinical Scoring System of Thyroid Storm (Thyrotoxicosis)

Answer

A

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

Question 8

Q

Hypothyroidism: Definition, etiology, s/sxs, PE

Answer

A

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

Q

Hypothyroidism: Dx & Tx

Answer

A

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

Q

When to refer to endo in hypothyroidism

Answer

A

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

Q

Hashimoto’s Thyroiditis

Answer

A

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

Q

Euthyroid Sick Syndrome

Answer

A

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

Q

Cretinism

Answer

A

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

Q

Riedel Thyroiditis

Answer

A

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

Q

Myxedema coma

Answer

A

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

Q

Define Myxedema

Answer

A

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

Question 17

Q

Thyroiditis Definition

Answer

A

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

Question 18

Q

Postpartum Thyroiditis

Answer

A

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

Q

Subacute Thyroiditis

Answer

A

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

Q

Suppurative Thyroiditis

Answer

A

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

Q

Drug-Induced Thyroiditis

Answer

A

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

Q

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

Answer

A

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

Q

Thyroid Cancer: Dx & Tx

Answer

A

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