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29 Cards in this Set
- Front
- Back
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embryological origin of thyroid
(and congenital disorder) |
between 2nd & 3rd pharyngeal pouches
migrates thyroglossal cyst= remnant of thyroid at base of tongue pyramidal lobe=remnant of thyroid duct |
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histology of thyroid
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columnar epis
TSH causes to grow only cells to uptake iodine full of colloid |
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colloid
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contents of thyroid epis
thyroglobulin & tyrosein |
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production of thyroid hormone
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peroxidase
-oxidize iodine -add iodine to tyroseine (MIT then DIT) -couple 2 DIT to make T4 deiodinase -activates T4 to T3 (mostly in blood) -T3 enters nucleus |
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thyroid hormone in circulation
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bound to thyroid binding globulin
(albumin 15%, transthrine 10%) |
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factors affecting TBG
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(thyroid binding globin)
increased -estrogen -(congenital excess) decreased -hepatic dz -(congenital defect) |
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function of Thyroid hormone
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4 B's
bone growth (synergism w/GH) brain maturation beta adrenergic -(increased CO, HR, SV & Ctx) BMR increase |
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regulation of TH
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TRH (in hypothal)
-stim'd by increased glyc use, GNG, lipolysis -stims TSH in pit inhibited by -feedback inhibition by T3 -ant pit decreases sensitivity to TRH TSI stimulates TSH (Graves Dz) |
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thyroid abnormalities
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TH excess
TH defic Thyroid nodules/Ca TH resistance Nonthyroidal illness |
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autoimmune destruction of thyroid cells
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Hashimoto's
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causes of hypothyroid
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hashimotos (#1 cause US)
iodine def (#1 cause world) surgery Pituitary congenital cretinism |
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big belly, infantile, decreased growth
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cretinism
(congenital hypothyroid) |
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fatigue, dry skin, hair loss, weight gain, cold intolerance
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hypothyroid
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hypothermia, bradycardia, thickened dry skin
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hypothyroid
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hyporeflexia
(myxedema coma if severe) |
hypothyroid (pathogmnemonic)
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treatment for hypothyroid
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replacement
-porcine -synthetic (levothyroxine, liothyronine) |
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TH4 replacement
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levothyroxine
7 day t 1/2 |
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TH3 replacement
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liothyronine
8 hr t 1/2 |
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causes of goiters
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TSH elevation (regardless of thyroid fctn)
-iodine deficiency -Grave's (TSI stims R) -primary hypothyroid -thyroid adenoma (multinodular "goiter") -secondary hyperthyroid (TSH secreting pituitary tumor) |
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causes of hyperthyroid
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Grave's (most common)
Thyroiditis Adenoma ("hot nodule", T3) receptor cross reactivity (HCG, molar pregnancy, HCG, LH, FSH activate beta) TSH secreting pituitary tumor Iatrogenic/facticious ectopic (struma ovari makes T4) |
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weight loss, increased appetite, BMR increased,
tachy, mental status, poor sleep weak, fatigue, decreased ex tol |
hyperthyroid
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mechanism of Graves
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autoimmune production of TSI (activates TSH R's)
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pretibial edema
EOM hypertrophy |
Grave's
(hyperthyroid) |
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thyroid storm
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clinical dx (don't wait for labs)
tachy, diaphoretic (sweat) |
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tachy, diaphoretic, cardiac, neuro thermo instability
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thyroid storm
underlying tyroid -MVA -accident |
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drugs that block TH synthesis
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(peroxidases)
PTU Methimazole |
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diffuse toxic goiter
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Grave's
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nodular toxic goiter
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hyperthyroid (Plummer's-selective T3 secreting tumor)
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diffuse simple goiter
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iodine deficiency
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