Thyroid Flashcards
thyroid effects: metabolic
-increased rate of glucose, fate, and protein metabolism, lipid mobilization, cholesterol metabolism by liver
thyroid effects: CV
-increased vasodilation, O2 consumption, CO, HR and contractility
thyroid effects: GI
-increased motility and secretion
thyroid effects: neuromuscular
-increased motor function and tone
T4 vs T3
- T4 is more abundant but less metabolically active
- T3 is less abundant but more metabolically active
- we think T4 is converted to T3 peripherally so that it has an effect
Hypothyroidism
- disorder of hypo-function
- congenital or acquired
- congenital = prenatal and present at birth
- sxs: cold intolerance, weight gain, constipation, sluggish, depression, fatigue
- F>M
- TSH increases as we age because we have decreased T4 and T3 and the body is trying to compensate
congenital hypothyroidism
- this is why we iodize salt
- preventable mental retardation
- from thyroid agenesis or failure to produce thyroid hormone or TSH, or dietary iodine deficiency
- agenesis typically has normal presentation at birth (cretinism)
cretinism
- no thyroid –> need tx forever
- incompatible with long life
- sxs appear in early childhood
- coarse dry skin, swollen tongue, umbilical hernia, open drooling mouth
- listeless, slow moving, slow feeding
- before birth, baby is living off of mom - if you begin treatment at birth, you can have normal development (must occur w/in 6 wks of birth)
Acquired hypothyroidism
- myxedema
- non-pitting mucous edema
- from thyroid damage - thyroidectomy, radiation, lithium, PTU, methimazole, high dose idoine, iodine deficiency, amiodarone
- hyaluronic acids and chondroitin sulfate accumulate in dermis –> draws fluid osmotically which is how you get edema
- tx is high dose steroids to combat autoimmune components
hashimoto’s thyroiditis
- MCC acquired hypothyroidism
- autoimmune destruction of gland (often occurs after thyroid trauma –> neck trauma, etc.)
- F:M = 5:1
- early hyperthyroid possible due to stimulation of gland by autoAbs
- caused by leakage of thyroglobulin/hormone and idiopathic
findings of hypothyroidism and tx
- gradual onset of weakness/fatigue, wt gain with loss of appetite, cold intolerance
- dry skin, pale yellow tone, coarse/brittle hair, loss of eyebrows, flatulence, distension, mental dullness, lethargy, impaired memory with CNS involvement
- tx: levothyroxine
myxedema coma
-end-stage hypothyroidism
-MC in elderly women with hx
-MC in winter
unable to metabolize medications
-coma, hypothermia, CV collapse, hypoventilation and severe metabolic d/o (CO2 retention, hypoxia, fluid/lyte imbalance, hypothermia)
Hyperthyroidism
- MCC = graves disease (high thyroid will suppress pituitary)
- ophthalmopathy and diffuse goiter
- other causes = multinodlar goiter, thyroid adenoma, excessive replacement (factitious)
hyperthyroidism s/s
- sxs resemble sympathetic activation and may heighten sensitivity to catecholamines –> HA, increased BP, tremors –> all opposite of hypothyroid
- palpitations, heat intolerance, nervousness, insomnia, breathlessness, increased bowel activity, oligo/amenorrhea, fatigue
- tachycardia, tremor, weight loss, weakness, moist skin, hair loss, exophthalmos
- hypermetabolic state - stimulants can be dangerous because they are already ramped up
tx of hyperthyroidism
- thyroid ablation - RAI
- subtotal or total thyroidectomy - particularly with tumor
- Tx sxs w/ b-blockers (helps with palpitations)
- antithyroid meds: propylthiouracil, methimazole
- iodinated contrast blocks synthesis
