Hyperthyroidism Flashcards
causes of hyperthyroidism
graves’ disease, TSH-secreting pituitary adenomas, toxic adenoma
graves’ disease is an
autoimmune syndrome that may include hyperthyroidism, diffuse thyroid enlargement, exophthalmos, pretibial myxedema, thyroid acropachy
in graves’ disease
thyroid stimulating immunoglobulin functions as an agonist at the TSH receptor, stimulating hormone production and release
Graves’s disease patients will have antibodies to
TPO
about 15% of graves’ patients will
spontaneously develop Hashimoto’s
TSH-secreting pituitary adenomas
release of biologically active hormone that is unresponsive to normal feedback control and occurs sporadically
toxic adenoma
autonomous thyroid nodule, seen as “hot: nodules on radioiodine scan
hyperthyroidism lab values
elevated free and total T3 and T4 with a low TSH and elevated RAIU
increased RAIU indicates
indicated true hyperthyroidism
decreased RAIU indicates that
the excess thyroid hormone is not a consequence of thyroid gland hyperfunction
thioamides
methimazole and propylthiouracil
methimazole
inhibits thyroid peroxidase (T4/T3 synthesis)
propylthiouracil
inhibits thyroid peroxidase, and inhibits 5’ deiodinase
half life of MMI
5 hours
half life of PTU
1 hour
duration of action of MMI
24 hours
duration of action of PTU
6-10 hours
metabolic clearance of MMI and PTU
decreased in renal and hepatic disease
MMI vs. PTU
MMI is 10-12 times more potent than PTU
MMI contraindications
pregnancy and breastfeeding
PTU contraindications
pregnancy
drug interactions of thioamides
warfarin - by correcting the underlying hyperthyroidism, metabolism of clotting factors will be reduced resulting in decreased response to warfarin
pregnancy and thioamides
PTU has historically been the preferred agent if treatment is necessary
thioamides - minor adverse effects
fever, rash, arthralgias, transient leucopenia
thioamides - major adverse effects
agranulocytosis, hepatitis, vasculitis, lupus-like syndrome
PTU initial dose
300-600mg divided three to four times daily
PTU maintenance dose
50-300mg divided two to three times daily
PTU max dose
1200 mg/day
MMI initial dose
30-60mg divided three times daily
MMI maintenance dose
5-30mg daily
MMI max dose
120 mg/day
changing doses of thioamides
doses should not be changed more than monthly
treatment with thioamides
treatment is continued for 12-24 months
baseline monitoring for thioamides
leukocyte count
labs to monitor for thioamides
TSH, FT4, TT4
adverse reactions to monitor for in thioamides
weakness, fatigue, easy bruising/bleeding, urinary symptoms
Radioactive iodine is used for
chemical ablation of thyroid gland
MOA of radioactive iodine
incorporated into thyroid hormone and thyroglobulin leading to follicular necrosis
treatment of choice for graves’ disease
radioactive iodine
pretreatment for radioactive iodine
pretreat with MMI/PTU in geriatric and cardio patients bc RI may transiently elevate thyroid hormone levels following treatment
with RI, euthyroid is reached in
2-6 months
in RI, hypothyroid typically happens within
4-12 months
contraindications of radioactive iodine
pregnancy, women should avoid getting pregnant for 6-12 months following therapy
thyroid eye disease and radioactive iodine
RAI exacerbates thyroid eye disease
exophthalmos treatment
begin glucocorticoid (prednisone 0.4-0.5 mg/kg/day) 4 to 7 days after RAI dose an taper over 2-3 months
possible reasons for surgery
- pediatric age group with toxic reaction to antithyroid medications
- pregnant women requiring high doses of PTU or having a toxic reaction to PTU
symptomatic treatment of hyperthyroidism
beta-blockers and calcium channel blocker
beta-blockers
inhibit adrenergic effect - control symptoms of tachycardia and hypertension
graves disease - most patients over 40 years old should receive
radioactive iodine
pregnant women and children should receive
antithyroid drugs as initial therapy
inadequately treated maternal hyperthyroidism can result in
fetal tachycardia, severe growth restriction, premature birth, and 9-fold increased incidence of low birth weight
PTU is preferred agent in pregnancy because
80-90% protein bound, therefor limited transfer into the placenta and breast milk as compared to MMI
type one amiodarone-induced thyroiditis
occurs due to drug metabolism (iodine-induced)
type one treatment of choice
thioamides
MMI dose for type one
40-60 mg/day
PTU dose for type one
100-150 mg qid
for severe type one you add
lithium 200-400 mg/day and titrate to serum concentration of 0.6-1.2 mEq/L
type two amiodarone-induce thyroiditis
occurs due to direct toxic effects (inflammation)
type 2 treatment choice
glucocorticoids
dosing for type 2
prednisone 0.5-1.5 mg/kg/day and taper over 2-3 months; for most patients 40-60 mg/day
iatrogenic hyperthyroidism
patients who receive too much thyroid hormone supplementation
acute thyroiditis
infection of the thyroid gland
symptoms of acute thyroiditis
acute onset of severe pain typically accompanied by fever, dysphagia, and erythema
thyroid function in acute thyroiditis
remains normal but ESR is typically elevated
treatment of acute thyroiditis
treatment with appropriate antibiotics usually results in complete resolution
subacute thyroiditis
symptoms similar to pharyngitis and is though to be caused by viral infection
the inflammatory process of subacute thyroiditis can lead to
destruction of tissue and fibrosis
in subacute thyroiditis patient typically presents with
symptoms similar to hyperthyroidism at first; after hormone is depleted, will develop hypothyroidism
subacute treatment
anti-inflammatory doses of ASA or NSAIDs is typically sufficient, if not glucocorticoids may be used
thyroid storm
uncommon, life-threatening condition characterized by an exaggeration of the manifestation of hyperthyroidism
TS has morality of
20%
precipitating factors of TS
surgery, obstetrical delivery, infections, or any other stressful medical illness
thyroid storm symptoms
high fever, tachycardia, tachypnea, dehydration, delirium, congestive heart failure, and rapid atrial fibrillation
treatment of thyroid storm
antithyroid drugs via loading dose and then chronic therapy, beta blockers, iodide in some patients
supportive care for TS
fluids/electrolytes, antibiotics, and APAP for fever
