Hypothalamus, pituitary, thyroid Flashcards
(25 cards)
GH
AE’s in children and adults
Somatropin
AEs:
Kids – HA, visual changes, papilledema, HTN
Adults – peripheral edema, carpal tunnel, arthralgia, myalgia
Somatomedin / Mecasermin
Mecasermin = IGF1 + IGFBP (^t1/2)
Pegvisomant
- Growth hormone receptor antagonist
- “peg” = increased t1/2
- treats acromegaly
Somatostatin analogs
- Octreotide = short t1/2 vs. LAR = longer t1/2
- - Lanreotide
Dopamine receptor agonists
Bromocriptine and Cabergoline @ D2 receptor
Thyrotropin
TSH
Sermorelin
hGHRH analog (escapes drug test detection)
Most effective time to treat GH deficiency?
first 2 years –> continues until growth stops
Pts that shouldn’t be treated with GH?
w/ History of Leukemia
Only Anterior Pituitary Hormone w/out therapeutic use and only pituitary hormone predominately regulated by suppression?
Prolactin
Protirelin / Thyrotropin alpha
– protirelin/TRH = used to test thyroid function
– thyrotropin/hTRH = dx test for thyroglobulin levels
CRH
– used only for diagnostic to distinguish b/t cushings and ectopic ACTH
Natural thyroid hormone
MOA
Metablolism
Levothyroxine (T4), Liothyronine (T3), Liotrix (T4 + T3)
- growth and development, esp in brain (ie cretanism)
- development of bone/teeth
- Calorigenic (inc BMR/O2 consumption)
- increases HR and Force of contraction (ino and chronotropic)
- MAINTAINS METABOLIC HOMEOSTASIS in many organs
Metabolism: biotransformation in liver (glucoronide conjugation and sulfate conjugation) –> bile excretion or ENTEROHEPATIC CYCLING (free hormones reabsorbed)
Type I vs Type II deiodinases
Type I = kidney,
Type II = pituitary, placenta, CNS – preferentially stimulated during fasting/dec caloric intake
which thyroid hormone do you give during pregnancy and why?
Liothyronine (T3) — if mother is hypothyroid, give during first trimester to prevent cretinism (essential for normal fetal brain development)
Thyroid binding proteins?
Thyroxine binding globulin (not thryoglobulin!), transthyretin, and albumin (familial dysalbuminic hyperthyroxinemia = inc overall Thyroid Hormone, normal free T4)
Immediate vs delayed effects of TSH on thryoid gland
Immediate: increased T4,3 secretion
Delayed: inc iodide uptake, hormone synthesis, proteolysis
Way later; hypertrophy and hyperplasia of thyroid
Receptors:
TSH = Gs /^^[TSH] = Gq
T3 = steroid mechanism
Iodide in tx of hyperthryoidism
- Large dose Iodide = decreases thyroid I absorption/ I metabolism by thyroid
- decreases size, vascularity of thyroid gland
**Uses: THYROID STORM!!, pre-operative
*contraindicated: prior to radioactive iodide tx (dilutes)
prefered method of preventing iodine deficiency?
Iodized salt
T3 mechanism of action
- T3 binds intracellular TRalpha1/beta1/beta2 receptor proteins
- translocate to nucleus and bind TREs
- inc or dec DNA transcription – can be modulated by coactivators/repressors
**RXR always required for thyroid hormone action!!
do you use a higher or lower dose of levothyroxine for children? how long does it take to see effect of thyroid replacement?
HIGHER dose for children
takes at least 4 days (transcription reg) to see effects, may take several weeks to get to steady state
Na131Iodide
Mec of administration, MOA, contradindications
Oral admin for hyperthyroidism
MOA: destroys all/part of parenchymal cells in a few weeks
Contraindicated in women of child bearing age!
Propylthiouracil (PTU!) and Methimazole
MOA: xPeroxidase = xIodination/organification/coupling
PTU = less potent so you give in pregnancy + inhibits peripheral T4 –> T3 conversion
Methimazole = crosses placenta and is concentrated in fetal thyroid
which antithryoid drug can you use in pregnancy?
PTU! – methimazole crosses placenta and is more potent
