NSG 533 Module 2 Thyroid Flashcards
TSH is a highly sensitive biomarker of the thyroid axis. A __________ change in FT4
levels will result in a 100-fold change in TSH
levels
two-fold
High TSH signifies hypothyroidism (or iatrogenic
underreplacement) and low TSH signifies hyperthyroidism (or
iatrogenic overreplacement).
-
There are three major goals in the treatment of hypo-thyroidism: replace the missing hormones, relieve signs and symptoms, and achieve a stable biochemical euthyroid state.
-
Despite the availability of a wide array of thyroid hormone products, synthetic _________________
is the treatment of choice (the gold standard)
for almost all patients with hypothyroidism.
LT4
levothyroxine (Synthroid)
There is no evidence that one LT4
product is better
than another. However, given the evidence that these products do
have differences in bioavailability, patients should be maintained
on the same LT4
product. Given the generic substitution regulations of most states, this is best accomplished by prescribing a
brand-name product or otherwise ensuring the product remains
constant and not allowing substitution.
-
Key concept
Most hypothyroid women who become pregnant will quickly need an increased dose of ____
, typically 20%
to 30% or two tablets per week above the prepregnancy dose.
The increased dose should be maintained throughout the pregnancy, with monthly TSH monitoring to keep ____ in the middle- to low-normal range
LT4
Drugs or Diet
(Things that alter LT4 Dose requirements)
Bile acid binders
Caffeine
Calcium
Charcoal
Chromium picolinate
Ciprofloxacin
Fiber
Grapefruit juice
H2
-blockers
Iron
Malabsorption syndromes
Oral bisphosphonates
Orlistat
Phosphate binders
(sevelamer, aluminum)
Proton pump inhibitors
Sodium polystyrene sulfonate
Soy
Sucralfate
Tube feeding
-
Graves
disease is the most common cause of hyperthyroidism;
-
Hyperthyroidism is related to excess thyroid hormone
production and secretion by the thyroid gland.
-
Goals of treating
hyperthyroidism are to relieve signs and symptoms, reduce thyroid hormone production to normal levels and achieve biochemical euthyroidism, and prevent long-term adverse sequelae
-
Because many manifestations of hyperthyroidism appear to
be mediated by the β-adrenergic system, _______________ are used to rapidly relieve palpitations, tremor, anxiety, and
heat intolerance
β-adrenergic blockers
Because nonselective agents can
impair the conversion of T4
to T3
, ________ and ________ are
preferred (2 beta blockers).
propranolol
nadolol
The thionamide agents ______ and ______ are used in the United States to
treat hyperthyroidism
propylthiouracil
(PTU)
methimazole (MMI)
Current recommendation for choice of antithyroid medication is to
use ____ in most patients, while _____ should only be used in
patients who cannot tolerate ______ or during first trimester of
pregnancy
MMI
PTU
MMI
Agranulocytosis is one of the most serious adverse
effects of antithyroid drug therapy.
-
Dosing regarding levothyroxine:
Titration by 25-50 mcg every 4-6 weeks until TSH normalizes
Levothyroxine normal adult dose:
Normal adult dose: 1.6 mcg/kg/day (~100-125 mcg/day) based on IBW (LBW)
Dosing exceptions and adjustments regarding levothyroxine:
EXCEPTIONS include elderly, chronically ill patients or history of cardiovascular disease . Initially 12.5-25 mcg/day, then titrate to maintenance dose until TSH normalizes
Expect higher requirements of ___________ during pregnancy.
Levothyroxine
Monitoring of TSH should be every ______ weeks after starting or dose/product change. If TSH is not in target range (0.5-2.5 mIU/L) alter dose in 10% to 20% increments. ..
6-8
The therapeutic index (TI) is the range of doses at which a medication is effective without unacceptable adverse events. Drugs with a narrow TI (NTIs) have a narrow window between their effective doses and those at which they produce adverse toxic effects.
-
Steady State of Synthroid: @ 6 weeks or 4-5 t1/2 ‘s … this is the basis for monitoring @ six weeks from start or changes!
-
(Regarding Synthroid monitoring)
Consider changes such as brand to generic, different generics manufactures, different pharmacies, etc
Any such change will require repeat lab monitoring @ ~ 6 weeks to confirm the same clinical response
-
This drug, a_________, is a drug interaction to Synthroid (and was highlighted in the weekly recap).
amiodarone
ALL patients should be educated that thyroid replacement should be taken first thing in the morning with water only and at least _____ minutes away from food or other medications.
30
Where binding interactions are concerned, the window is _____ hour separation
two
________ should be used in virtually every patient who chooses antithyroid drug therapy for GD, except during the first trimester of pregnancy when propylthiouracil is preferred, in the treatment of thyroid storm (inhibition of peripheral conversion), and in patients with minor reactions to ______________ who refuse radioactive iodine therapy or surgery
Methimazole
Why does amiodarone pose a unique concern to thyroid disorders?
Amiodarone: normal thyroid autoregulation is lost because of the relatively high iodine content.
This fact can lead to a situation where amiodarone can cause BOTH hyper- and hypo- thyroidism, depending on the patient, through several processes.
