endocrine Flashcards
thyroid hormone fxn
T4 = 90%, T3 = 10% of production, also calcitoninaffects almost all body tissuesmaintains metab stability by regulating O2 reqs & metabprotein synthesis & catabolism (if x hormone)temp regimpacts CHO metab: enhances epi to stim glycogenolysis & gluconeogenesisaffects lipid metabolism (accelerates degradation of LDL)↑s AV node depol to ↑ HR↑s resp drive, mental alertness, GI motility
when hypothalamus releases TRH x2
in resp to ↓ circulating T3 & T4cerebral cortex resp to ↓ body T or cold
TRH & TSH impact
- TRH: anterior pituitary → release TSH * TSH stimulates thyroid to release T3 & T4
thyroid hormones: secreted most vs active hormone
T4 secreted 90%unbound T3 is most active (90% from T4 deiodination)
hormone ↑ in primary hypothyroidism
TSH
hormone ↓ in primary hyperthyroidism
aka Graves DiseaseTSH
hormone ↑ in primary hyperthyroidism
FT4 (false if on heparin)T4
hormone ↓ in primary hypothyroidism
FT4T4
palpable thyroid nodules: mgmt
1. thyroid fxn tests (TSH, FT4, thyroid antibodies)#2. imaging – US (assess if more than 1 nodule, if it is a cyst or solid)#3. Fine Needle Aspiration bx
thinning of outer third of eyebrows sign of
hypothyroidism
primary vs secondary hypothyroidism
primary: gland dysfxnsecondary: pituitary or hypothalamus dysfxn (normal or ↓TSH)
most common cause of hypothyroidism
Hashimoto’s (autoimmune)- evidence of ab to thyroid ags
Hashimoto’s Thyroiditis
transient hyperthyroidism w/ an ↑in antibodies fol↓ed by hypothyroidism
Graves Disease
autoimmune disease w enlarged thyroid goiterthyroid eye disease (opthalmoptosis)↓TSH↑ T4 or Ft4↑ antithyroglobulin ab, alk phos, thyroid radioactive iodine uptake)hypercalcemia
hypothyroidism tx
Levothyroxine (Synthroid, Levoxyl)
Graves Disease tx
- inderal (Propranolol)- thiourea drugs: PTU, methimazole (Tapazole)- radioactive I- surgery
thiourea drugs
block synthesis of T3 & T4PTU, methimazole (Tapazole)call NP: fever, infection, agranulocytosis (abs neut count lt 500)
hypothyroidism: monitor & goal
TSH (barometer vs T4 for dx)maintenance dosage levothyroxine 100 - 200 ug/d
if thyroid replacement too rapid
↑HR, dyspnea, orthopnea, angina, palpitations, nervousness, insomnia
thyroid crises + s/s
myxedema or thyroid stormAMS, altered thermal reg, precipitating event/illness
- myxedema *
Severe HYPOTHYROIDISM- ↓ thyroid fxn + subsequent ↓T3 & T4 → alteration F/E - ↑ capillary permeability, fluid retention- non-pitting edema hands/feet- 50-80% mortality rate d/t hypercapnia & hypoventilation
- myxedema presenting s/s *
- resp depression, hypotension *stupor, coma, hypothermia