Thyroid Disorders Flashcards
Hyperthyroidism: definition and etiology
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)
Hyperthyroidism: S/S
- 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
Labs in Hyperthyroidism:
TFTs
TSH is low (suppressed)
T3 and T4 are high
TX options in Hyperthyroidism:
-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
Monitoring in Hyperthyroidsim:
- 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
Hypothyroidism: S/S
- 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
Primary Hypothyroidism:
Primary: defective thyroid hormone synthesis
Elevated TSH
Low T3 and T4
Causes: Hashimoto’s, subacute thyroiditis
Less common: congenital, iodine deficiency
Secondary Hypothyroidism:
Secondary: pituitary or hypothalamic failure
Low TSH, T3, and T4
Causes: Cushing’s, pituitary adenoma, acromegaly
TX of Hypothyroidism:
*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)
Levothyroxine: pt education, initiation of drug and monitoring
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
Hypothyroidism and pregnancy:
- 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