Flashcards in Thyroid Deck (52):
What is hyperthyroidism?
Hypermetabolic state resulting from excess thyroid hormone
What are the results of Hyperthyroidism?
↑ Metabolic rate
Excessive body heat generation
↑ Cardiac activity
What are the causes of hyperthyroidism?
1. More common in Caucasian & Hispanic
2. Females > males
3. Familial tendency
4. Autoimmune Dz
5. Overexposure to iodine
A. Expectorants, amiodarone, seaweed, contrast dye
What is grave's dz?
1. Most common cause (80-90% of cases)
2. Diffuse toxic goiter
3. Autoimmune Dz
What is toxic adenoma?
1. Single benign hyperfunctioning thyroid tumor resulting from a genetic mutation
2. “Hot" thyroid nodule
What is Toxic Multinodular Goiter (Plummer’s Dz)?
2° to hyperplastic response of entire thyroid gland to a stimulus (iodine deficiency)
What is Transient Thyroiditis?
1. Subacute thyroiditis
A. Can cause thyrotoxicosis & hypothyroidism
B. De Quervain's thyroiditis
-Sudden, painful enlargement of thyroid gland w/ fever, malaise & muscle aches (viral mediated)
2. Hashimoto’s thyroiditis
A. Autoimmune disease
What are the rare causes of hyperthyroidism?
1. ↑ Iodine ingestion w/preexisting thyroid hyperplasia or adenoma
2. Thyroid neoplasm
4. Hydatidiform mole
5. Pituitary neoplasm
A. Hypersecretes TSH
What are the sxs of hyperthyroidism?
↓ Menses (oligomenorrhea, amenorrhea)
Warm, moist skin
Thin, fine hair
What are the sxs of grave's dz?
2. Lid retraction
3. Lid lag
5. Painless pretibial swelling (myxedema)
6. Less common
B. Blurred vision
D. Increased lacrimatio
What is thyroid storm/severe thyrotoxicosis?
1. Abrupt, severe exacerbation of thyrotoxicosis
2. Rare potentially fatal complication of hyperthyroidism
What causes thyroid storm/severe thyrotoxicosis?
1. Occurs in patients with untreated (or undiagnosed) or undertreated hyperthyroidism
2. Precipitating event
What are the sxs of thyroid storm?
1. High fever
2. Tachycardia (>140)
3. CHF in elderly
6. Mental status changes (psychosis, coma, seizures)
What are the dx studies for hyperthyroidism?
1. ↓ TSH
2. ↑ Free Thyroxine (Free T4)
A. Normal in subclinical hyperthyroidism
-Pituitary adenoma secreting TSH
3. ↑ Free Triiodothyronine (Free T3)
4. Anti-TPO Ab (anti-thyroid peroxidase Ab)
A. ↑ in Graves’ Dz
5. Anti-TSHR Ab (antithyrotropic receptor Ab)
A. ↑ in Graves’ Dz
What imaging and further studies are used in hyperthroidism?
1. Thyroid U/S
A. If thyroid nodule or nodular goiter on exam
2. 24-hr radioiodine uptake (I-123) & scan
A. Urine or serum HCG prior to testing
3. FNA & Bx if nodule confirmed
What are the I-123 Uptake and scan results in Toxic adenoma?
1. Normal gland size
2. “Hot” nodule
3. Single focus of uptake
What are the I-123 Uptake and scan results in graves' disease?
1. Diffuse glandular enlargement
2. ↑ Homogenous I-123 uptake
What are the I-123 Uptake and scan results in a multinodular goiter?
1. Diffuse enlargement w/ nodules
2. Areas of ↑ & ↓ I-123 uptake (heterogenous)
What disorders require a thyroid biopsy?
All “cold nodules” require biopsy to R/O thyroid cancer
How does radioactive Iodine treat hyperthyroidism?
1. Destroys gland
2. Most common treatment in non-pregnant adults, patients w/ large goiters, euthyroid not met after 1 yr of oral Tx, & when malignancy is likely (prior to surgery)
3. Single oral dose
4. Can worsen eye sx’s
What are examples and functions of the thionamide drugs?
1. Methimazole/Tapazole (MMI) or Propylthiouracil (PTU)
A. Blocks production of thyroid peroxidase/inhibits new hormone synthesis
What is the goal of hyperthyroid treatment?
1. euthyroid in 3-8 wks and cont. for 12 to 24 mo.
2. Useful in preparing patients for surgery or radioactive iodine treatment
What is the drug of choice for hyperthyroidism in pregnant and breast feeding women?
What are the benefits of Methimazole/Tapazole (preferred) over PTU?
Lower S/E, longer duration of activity
Agranulocytosis - rare complication
What is the role of steroidsin the treatment of hyperthyroidism?
1. Inhibits peripheral T4->T3 conversion
2. Ophthalmopathy responds best to IV methylprednisolone, or high-dose tapered prednisone Tx
Why are beta blockers used in hyperthyroidism?
1. Propranolol controls palps, tachy, anxiety, tremors
2. Initial treatment of choice for Thyroid Storm
What are the surgical options for hyperthyroidism?
Thyroidectomy- partial vs total
requires thyroid hormone supplementation
What are the indications for thyroid surgery?
1. Children (Graves’)
2. Pregnant women
3. Pts who refuse I-131 therapy
4. Pts w/ severe eye symptoms
5. Requires thyroid hormone supplementation
What pt education needs to take place for hyperthyroidism?
1. Refer pt to Ophthalmologist
A. Emergency care for eye pain, optic nerve compression, color vision loss
2. Smoking cessation-worsens eye symptoms
3. Medication compliance is important
A. Risk of thyroid storm
B. Patient education on symptoms/risk
How is thyroid storm treated?
2. Treat underlying cause (infection, etc)
4. Beta Blocker
A. 80-100 mg PO or PR stat, then 30 mg PR q 8h
6. Inhibit thyroid hormone release
A. Lugol’s sol’n: Iodide 10 gtts q 8h OR Sodium iodide 250 mg IV q 6h
B. Corticoteroids: Hydrocortisone 100 mg IV Q8h
1. Inadequate secretion of thyroid hormone
2. > 90% of cases are primary caused by thyroid gland dysfunction
3. More common in caucasian females
4. ↑ prevalence w/ age
What are the causes of primary hypothyroidism?
A. Hashimoto’s thyroiditis (most common cause > age 8)
-Cell- & Ab-mediated destruction of thyroid tissue
B. Previous thyroid surgery
C. Radioactive iodine therapy
D. External radiotherapy
E. Meds such as lithium, amiodarone, sulfonamides, interferon, interleukin-2
F. Congenital ≈ 1 per 4000 births
What are the causes of secondary hypothyroidism?
1. Pituitary dysfunction
2. Postpartum necrosis
What are the sxs of hypothyroidism?
1. Thinning, dry hair
2. Loss of outer 1/3 of brows
A. Dry, coarse, cool, edema of eyelids & hands (myxedema)
5. Wt. gain
6. ↓ Appetite
7. Poor memory
9. Cold intolerance
10. Dulled expression
11. Macroglossia: uncommon unless longstanding untreated hypothyroid
12. +/- Thyromegaly
14. Slow relaxation phase of DTR’s
15. Possible CTS (carpal tunnel syndrome)
What is the most common thyroid disorder in the US?
1. Hashimoto’s Thyroiditis
2. Affects 1% of the population & 5% over age 65
3. More common in women 7:1
What is the etiology and precipitating factors for hypothyroidism?
1. Cause: combo of genetic & environmental factors
2. Precipitating factors:
C. Excess iodine intake
D. Radiation exposure
What are the early signs of hashimoto's thyroiditis?
1. Tender enlarged thyroid
6. Wt. loss
What are the late signs of hashimoto's thyroiditis?
1. +/- Nontender, enlarged thyroid
3. Wt. gain
4. Delayed reflexes
What are the characteristics of subclinical hypothyroidism?
TSH high, T4 normal
What are the characteristics of secondary hypothyroidism?
Inadequate TSH secretion from pituitary
What are the characteristics of tertiary hypothyroidism?
Inadequate thyrotropin-releasing hormone(TRH) from hypothalamus
What is the ddx for hypothyroidism?
2. Chronic fatigue syndrome
What are the diagnostic studies in hypothyroidism?
1. ↑ TSH
A. Most sensitive screen (normal 0.50-5.0 mIU/L)
2. ↓ Free T4
A. Normal in subclinical hypothyroidism
3. Thyroid autoantibodies (Anti-thyroid antibodies)
A. Anti-TPO Ab (anti-thyroid peroxidase antibodies)
B. Anti-Tg Ab (anti-thyroglobulin antibodies)
C. ↑ in Hashimoto’s thyroiditis but not always
4. Thyroid Scan
A. Only for nodule
B. Followed by FNA & Bx to R/O cancer
How is hypothyroidism treated?
1. Synthetic thyroxine (T4)
A. Levothyroxine daily am dose
A. Thyroidectomy if large gland compromises tracheoesophageal function or suspicious for malignancy
What is myxedma coma?
1. Severe hypothyroidism leading to ↓ mental status & hypothermia
2. Medical Emergency w/ high mortality rate
What causes myxedema coma?
1. Long standing undiagnosed or undertreated hypothyroidism
2. With additional insult
A. Infection (pneumonia)
B. Systemic disease
D. Medications: Sedatives, anesthetics, opiates, antidepressants)
E. Cold exposure
What are the the sxs of myxedema coma?
1. General: Hypothermia ( < 95° F rectal)
2. HEENT: Myxedema facies, macroglossia
3. Neuro: Lethargy or stupor, areflexia
4. Cardiac: Hypotension/shock, bradycardia, low cardiac output
5. Vascular: ↓plasma volume, increased vascular permeability, fluid accumulation
6. Pulmonary: Depressed resp. drive, pleural effusions
7. Renal/GU: Bladder distention, hyponatremia
8. GI: Gastric atony, megacolon, ileus
What is the treatment for myxedema coma?
2. Airway-if resp acidosis
3. T4 loading dose
A. Levothyroxine 300-500 mcg IV over 15 min, then 100 mcg IV q 24 h
4. Hydrocortisone 100 mg IV bolus, then 50 mg IV q 12 h
A. Give until adrenal insuff. is ruled out (normal serum cortisol)
5. Progressive rewarming of pt
6. Pan-culture then empiric Abx
7. IV hydration w/ D5NS
8. +/- Vasopressors
What is the tx for hashimoto's thyroiditis?
1. Start thyroid hormone replacement Tx
A. Prevents or corrects the hypothyroidism
B. Halts thyromegaly
What can hashimoto's thyroiditis initially present as? How do you managed this?
1. Can initially present as hyperthyroidism
2. Treatment-until initial hyperthyroid period resolves
A. Bed rest & NSAIDs
B. Some need steroids to ↓ inflammation & control palpitations
C. Beta blocker to ↓ the HR & ↓ tremors
What are the indications to treat myxedema-suspected pts before labs come back?
1. Thyroidectomy scar
2. Hx of I131 therapy