Thyroid Disorders Flashcards

1
Q

Hyperthyroidism: definition and etiology

A

Excessive levels of circulating thyroid hormone
Causes
Toxic diffuse goiter (Graves’ disease)
Hyperfunctioning thyroid nodule
Anterior pituitary disorders
Toxic MNG (Plummer’s disease)
Iodine-induced disease (e.g., amiodarone)

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2
Q

Hyperthyroidism: S/S

A
  • Tachycardia
  • Arrhythmias
  • Palpitations
  • Weight loss
  • Diarrhea
  • Nausea and vomiting
  • Sweating (hyperhydrosis)
  • Flushing
  • Hair loss
  • Oligomenorrhea in women
  • Impotence in men
  • Decreased libido in men
  • Restlessness/insomnia
  • Emotional lability
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3
Q

Labs in Hyperthyroidism:

A

TFTs
TSH is low (suppressed)
T3 and T4 are high

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4
Q

TX options in Hyperthyroidism:

A

-Symptom relief
Propranolol: start 80–160 mg daily divided BID
Atenolol: if history of RAD or risk for hypoglycemia
-Definitive treatment
Antithyroid drugs (response takes 4–8 weeks)
Methimazole: start 15–30 mg daily or divided TID
Propylthiouracil (PTU): risk of hepatoxicity
-Radioactive iodine
-Surgery

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5
Q

Monitoring in Hyperthyroidsim:

A
  • Check TSH/FT4 every three weeks until euthyroid
  • Goal is normalization of TSH
  • Baseline and periodic WBC for first 4 months
  • Mild leukopenia is common
  • Decrease medication for WBC less than 1,500
  • Then 3 months, 6 months, annually
  • May become hypothyroid as a result of treatment
  • TSH is first indicator
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6
Q

Hypothyroidism: S/S

A
  • CV: bradycardia
  • Heme: amenia (poor absorption, decreased erythropoetan, or EPO)
  • GI: constipation, weight gain, elevated lipids, fluid retention
  • Skin: dry flaky skin, brittle hair, slow wound healing, cold
  • Reproductive: anovulation, decreased libido, SAB
  • Renal: increased body water, dilutional hyponatremia, decreased EPO
  • Neuro: confusion, memory loss, night blindness, ataxia
  • MSK: joint aches and stiffness, decreased DTRs
  • Miscellaneous: fatigue and depression
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7
Q

Primary Hypothyroidism:

A

Primary: defective thyroid hormone synthesis
Elevated TSH
Low T3 and T4
Causes: Hashimoto’s, subacute thyroiditis
Less common: congenital, iodine deficiency

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8
Q

Secondary Hypothyroidism:

A

Secondary: pituitary or hypothalamic failure
Low TSH, T3, and T4
Causes: Cushing’s, pituitary adenoma, acromegaly

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9
Q

TX of Hypothyroidism:

A
*All patients with TSH greater than 10 mcU/mL
Goals
-Correction of hypometabolic state
-Resolution of symptoms
-Normalization of TSH and FT4
-TSH target 0.3–3.0 mcU/mL
Synthetic thyroid hormone replacement
Levothyroxine (T4)
Liothyronine (T3)
Liotrix (4:1 ratio mix of T4 and T3)
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10
Q

Levothyroxine: pt education, initiation of drug and monitoring

A

Start 50–100 mcg daily for young healthy patients
Start 12.5–50 mcg daily if over 50 years of age or heart disease
** Provide education: must take medication on an empty stomach
-Recheck TSH and FT4 in 4 to 6 weeks
If clinically euthyroid, recheck 4 to 8 weeks
-Still clinically hypothyroid with elevated TSH
Increase by 50 mcg a day if young and healthy
Increase by 25 mcg a day if over 50 years of age or heart disease
Recheck 4 to 8 weeks again
-If euthyroid on two checks, TSH at 6 months, then yearly
* Refer to Endocrine if TSH doesn’t normalize

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11
Q

Hypothyroidism and pregnancy:

A
  • Check TSH and FT4 at 8 week’s and 6 month’s gestation
  • May need to increase maintenance dose of levothyroxine by 25%
  • If so, check TSH every 6 weeks
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