Term
| The single most sensitive test of thyroid hormone stat is ___ |
|
Definition
|
|
Term
| Tx hypothyroidism: drug, dosing, course (2) |
|
Definition
Levothyroxine/T4 qd
Increase dose every 2 weeks until TSH is normal, monitor with Free T4
Takes 2-3 weeks to see it take effect because the T4 has to fill all the TBG sites before it can stay in the blood as Free T4
Full resolution by 4-6 weeks (skin/nails may take longer)
(Don't use T3 because t1/2 too short and it's too toxic.) |
|
|
Term
| Levothyroxine: S/E (4, 3), contraindications |
|
Definition
S/E have to do with overtreatment (determine this by measuring TSH: suppressed indicates that you're overtreating, which is causing the symptoms)
Adults: heat intolerance, tachycardia, weight loss, nervousness
Kids: insomnia, restlessness, accelerated bone growth
Watch out for patients with known/suspected CAD or myocardial issues because levothyroxine can cause MI or afib = start them off slowly |
|
|
Term
|
Definition
Intubate and ventilate: reverse hypoxia and hypercapnia
Glucose: reverse hypoglycemia
Loading dose thyroxine: has to be big because the TBG sites are empty and need to be filled before there can be Free T4 in the blood
You know the patient's doing better when body temperature and mental status improve
IV fluids: use with care since the patient's already hyponatremic! |
|
|
Term
| Drugs that can cause hypothyroidism (2) |
|
Definition
Corticosteroids: inhibit release of TRH and TSH, prevent T4=>T3
Lithium: inhibits T3/3 secretion in patients with previous hypothyroidism |
|
|
Term
|
Definition
KI
Methimazole
PTU
Propranolol
I-131 ablation |
|
|
Term
| Drug that modifies tissue response to excess T4/3 |
|
Definition
|
|
Term
| Drugs that prevent organification of iodide and synthesis of T4/3 (2) |
|
Definition
|
|
Term
| Drugs that prevent T4=>T3 (2) |
|
Definition
|
|
Term
| Drug that prevents release of T4/3 |
|
Definition
|
|
Term
| 1st-line hyperthyroidism drug |
|
Definition
|
|
Term
| Propranolol: MOA (2), physiologic effects, dosing issue |
|
Definition
Blocks B1 and B2-R: controls autonomic symptoms like tachycardia, palpitations, tremor, anxiety
Prevents T4=>T3: controls heat intolerance, diaphoresis, weight loss, fatigue
Gotta give a lot at first since its metab will be increased in hyperthyroidism |
|
|
Term
| Main drugs for tx hyperthyroidism (2) |
|
Definition
|
|
Term
|
Definition
Inhibit thyroid peroxidase: inhibits conversion of iodide to iodine
Inhibit MIT/DIT coupling
PTU: also blocks T4=>T3
Overall: decreased synthesis of T4/3 |
|
|
Term
| Thioamides: physiologic effects (3) |
|
Definition
Slow onset depletion of T4 stores
After euthyroid state, minority will go into remission within 1mo-2yrs
Most will relapse, though, and then treated with I-131 |
|
|
Term
|
Definition
Skin rash (tx w/ antihistamine)
Reversible agranulocytosis (rare)
Prego
-Only use PTU because it's highly protein-bound = doesn't cross the placenta
-Some babies will have goiter, though, so wanna use the smallest dose for the shortest amount of time
PTU: anti-vitK activitiy = potentiates warfarin |
|
|
Term
|
Definition
Stop PTU/KI 1 week prior to tx to allow for good I-131 uptake
Rapidly absorbed and concentrated in thyroid (want 40-60% uptake)
Beta-radiation kills the follicular cells
Follicular cell lysis can cause thyroid storm, so give KI prn
Avoid kids and pregos
May become euthyroid and then hypothyroid, requiring levothyroxine |
|
|
Term
| KI: MOA (2), physiologic effect |
|
Definition
Prevents thyroglobulin proteolysis = inhibits release of T4/3
Transiently inhibits iodide trapping = inhibition of organification of iodide
Decreases size and vascularity of the gland over 2-7 days |
|
|
Term
|
Definition
Prep thyrotoxic patients for emergency surgery
Thyroid storm
Not used routinely or as single-agent |
|
|
Term
|
Definition
Hyperthyroidism: gland actually uses the iodide to make T4/3 ("escape")
Allergies: skin rash, fever, facial swelling, joint pain, possible dyspnea
Fetal goiter
Iodism (rare): burning sensation in mouth/throat, metallic taste, sore gums
Delays action of PTU
Prevents use of I-131 for a few weeks |
|
|
Term
| Causes of increased TBG concentration (3) |
|
Definition
OCPs
Prego on levothyroxine
Opiates |
|
|
Term
| Drugs that decrease TBG concentration (3) |
|
Definition
Glucocorticoids
Androgens
Salicylates |
|
|
Term
| Drugs that increase T4 clearance (5) |
|
Definition
Induce CYP450
-Phenobarbital
-Phenytoin
-Carbamazepine
Increase fecal loss
-Cholestyramine
-Colestipol |
|
|
Term
| Precipitating factor of thyroid storm |
|
Definition
|
|
Term
|
Definition
Propranolol: single-most important drug
KI or PTU
Supportive care |
|
|
Term
| Dissection of the pituitary stalk causes ___ DI |
|
Definition
Transient
Disappears because eventually the normal osmotic stimuli elicit the release of AVP directly from the HT |
|
|
Term
| Aldo controls ____ Na not Na ___ |
|
Definition
| Total body Na NOT Na concentration |
|
|
Term
| ADH controls Na ___ not ___ Na |
|
Definition
| Na concentration NOT total body Na |
|
|
Term
| If there's an issue with concentrating urine, think ___ unless ___ |
|
Definition
| Think ADH unless on some other drugs |
|
|
Term
| V1R has a ___ effect while V2R has a ___ effect |
|
Definition
V1R has a vasopressor effect at high [ADH]
V2R has a water reabsorption effect at low [ADH] |
|
|
Term
|
Definition
Stimulates adenyl cyclase-coupled ADH-R on the basolateral membrane of the late distal tubule and collecting duct
cAMP, kinases, insert pores in the apical membrane (this is where most anti-ADH drugs work)
Hyperosmolar gradient in the interstitial fluid causes tubular water to move into the interstitium thereby concentrating the urine |
|
|
Term
| Lithium and PGE inhibit ___ |
|
Definition
| ADH-dependent adenyl cyclase |
|
|
Term
| Additional V2R effects (2) |
|
Definition
Increases release of Factor 8 from hepatocytes and vWF from endothelial cells
Relaxes smooth muscle = decreased TPR |
|
|
Term
|
Definition
|
|
Term
| DDAVP: MOA, pharmacokinetics (3) |
|
Definition
ADH analog
t1/2 6-20 hrs
V2:V1 activity is 4000, so little VC
URI rhinitis or congestion slow absorption |
|
|
Term
| DDAVP: physiologic effect, water intake |
|
Definition
Marked reduction in daily urine volume
Limit water intake to just enough to satisfy thirst to avoid hyponatremia |
|
|
Term
|
Definition
Nocturnal enuresis
Hemophila A and vWD |
|
|
Term
|
Definition
HTN (rare)
Hypotension with tachycardia (IV or subcu)
Hyponatremia with excess water intake |
|
|
Term
| HCTZ: MOA (3), physiologic effect |
|
Definition
Decreases GFR: urine is less dilute
Natriuresis contracts ECF volume = increased salt/water reabsorption in the proximal tubule = less volume sent to the distal tubule to be diluted
Inhibits NaCl reabsorption in the distal tubule
Decreases urinary volume |
|
|
Term
|
Definition
Adequate water intake
Partial: HCTZ or larger doses of DDAVP if partially nephrogenic
Complete: HCTZ or indomethacin |
|
|
Term
|
Definition
Block synthesis of renal PGE, which normally inhibits ADH-stimulation of adenyl cyclase
ADH can now stimulate adenyl cyclase |
|
|
Term
|
Definition
Most Li reabsorbed in PT
Rest can be reabsorbed in the principal cells of the late DT and CD
-Li goes where Na goes and inhibits ADH
-Only place where Na and Cl don't travel together (Cl travels paracellularly) |
|
|
Term
| Tx Li-induced nephrogenic DI (1) |
|
Definition
|
|
Term
| Amiloride: MOA, physiologic effects (2) |
|
Definition
Blocks Na-channels in the principle cells = Li can't enter
Decreases urine volume 30-40% and increases osmolality to >300
Doesn't decrease the renal clearance of Li! |
|
|
Term
|
Definition
The increased salt/water reabsorption in the proximal tubule means that most of the Li may be reabsorbed instead of cleared
Gotta reduce the dose to prevent toxicity |
|
|
Term
|
Definition
Non-endocrine cancers especially small cell lung cancer
CNS issues
Pulmonary infections
Adrenal insufficiency/hypothyroidism |
|
|
Term
|
Definition
Demeclocycline
(Chlorpropaminde) |
|
|
Term
| Chlorpropamide: MOA (2), other indication |
|
Definition
Increases release of ADH
Potentiates renal effects of ADH
Induces insulin release in NIDDM |
|
|
Term
| Tx SIADH-induced hyponatremia (3) |
|
Definition
Restrict water intake: urine output will exceed what's consumed = plasma concentration will rise
Demeclocycline
Infuse with NaCl (severe cases) |
|
|
Term
| Demeclocycline: MOA, indication |
|
Definition
Tetracycline
Inhibits adenyl cyclase = inhibits ADH action in the collecting duct
Used when Na <120 and the patient has severe neuro symptoms |
|
|
