Hypothyroidism Flashcards
What is hypoT?
- most common clinical thyroid disorder in US
- deficient thyroid hormone production
What causes primary hypoT?
- autoimmune disorder
- loss of thyroid tissue
- iodine deficiency, anti-thyroid drugs
What causes secondary hypoT?
-pituitary insult
What causes tertiary hypoT?
- anorexia
- hypothalamic tumors
What are the symptoms of hypoT?
- fatigue
- cold intolerance, dry/cool extremities
- facial puffiness, periorbital swelling
- bradycardia
- constipation
- forgetful, paresthesias, delayed DTRs
- menorrhagia, anemia, irregular menses
- goiter is still possible!
Subacute Thyroiditis
- inflammation of thyroid gland following viral infection
- hyperT –> euT –> hypoT
- 2-4 months of sxs
- tx not always necessary
Postpartum Thyroiditis
- within 3-6 months of delivery
- thyroxine binding globulin increases in pregnancy and with OCP use then drops
- > 50% remain hypoT
Silent Thyroiditis
- not associated w/ pregnancy or delivery
- similar course as subacute (2-4 months)
- but clinically like Hashimoto’s
- spontaneous resolution expected
What is another name for Hashimoto’s thyroiditis?
chronic lymphocytic thyroiditis
Hashimoto’s
- most common adult cause of hypoT
- firm goiter from chronic TSH stimulation
- myxedema possible
- autoimmune disorder
- genetic predisposition
Post-therapeutic/Iatrogenic Thyroiditis
- radioactive iodine induce: hypoT can occur early or late depending on dosage
- subtotal thyroidectomy: highest risk in first year
Goiter
- most pts with non-Hashimoto goiter are euthyroid or hyperT
- goitrous hypoT in endemic area: due to iodine deficiency, basically eliminated with iodized salt
What is the most common form of congenital hypoT?
- cretinism
- found in severely deficient areas
- major cause of mental retardation
Euthyroid Sick
- clinical syndrome found in acutely ill patients
- commonly decreased total and unbound T3, normal T4, and TSH
- can also see elevated T3 and/or T4 initially
Myxedema Coma
-life-threatening complication of hypoT
Sxs of Myxedema Coma
- extreme hypothermia (75-90 F)
- seizures
- areflexia
- bradycardia
- respiratory depression
- coma
What is the TSH level in hypoT?
- elevated in primary hypoT
- normal or decreased in 2ary or tertiary
What is the T4 level in hypoT?
typically low
What is the T3 level in hypoT?
may be normal in primary hypoT
HypoT Treatment
- discontinue/lower dose of offending medication
- thyroid hormone preparations (synthetic T4 preferred)
- annual TSH monitoring
