USMLE Step 2 (3)-Thyroid Disease
Transcript of USMLE Step 2 (3)-Thyroid Disease
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USMLE Step 2 — Lesson 15: Thyroid Disease
THYROID DISEASE
HYPOTHYROIDISM
Clinical features• Signs of metabolic slow-down, ie, lethargy, fatigue, slowness of speech
• Cold intolerance
• Constipation
• Weight gain
HYPOTHYROIDISM
Clinical features• Voice and hair change
• Nonpitting edema, ie, myxedema
• Diminished deep tendon reflexes
• Bradycardia
HYPOTHYROIDISM
Myxedema coma• ntreated se!ere hypothyroidism
• "ay be triggered by acute precipitant, eg, infection• #atients may present with hypothermia, hypoglycemia, shoc$, and
hypo!entilation• %herapy& thyroid and adrenal hormone replacement
HYPOTHYROIDISM
Diagnosis of y!otyroidism• 'ow total %( and %)
• *le!ated %S+
• 'ow radioacti!e iodine upta$e
HYPOTHYROIDISM" Cronic Tyroiditis #Hasimoto$s Tyroiditis%
• utoimmune disorder usually affecting women
• ntithyroid antibodies present
• %hyromegaly due to lymphocytic infiltration
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• +ypothyroidism gradually de!elops
HYPOTHYROIDISM" Cronic Tyroiditis #Hasimoto$s Tyroiditis%
Diagnosis• ntimicrosomal antibodies or antithyroglobulin antibodies
• Suspected in patients with symmetric, usually nontender, nontoxic goiters
• #atients may be euthyroid or hypothyroid• %reat with '-thyroxine to decrease sie of gland and for the hypothyroidism
HYPOTHYROIDISM
Tera!y• %hyroid hormone replacement, ie, synthetic '-thyroxine
• Begin with low doses in older patients and in those with se!erehypothyroidism
HYPERTHYROIDISM
Clinical features• ./!eracti!e. metabolism
• Sweating
• +eat intolerance
• Weight loss
• Sinus tachycardia• trial fibrillation 0apathetic hyperthyroidism in the elderly1
HYPERTHYROIDISM
Etiology• 2ra!es3 disease
• Nodular toxic goiter
• Subacute thyroiditis
• 4actitious
• #ituitary tumors
HYPERTHYROIDISM
Clinical features• Diarrhea
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• Warm, moist s$in
• 5estlessness and tremor
• /phthalmic findings& lid lag and the hyperthyroid 6stare7
• %hyroid exophthalmos& seen only in 2ra!es8 disease9 due to infiltration of
the extraocular muscles
HYPERTHYROIDISM
Tyroid storm• Se!ere exacerbation of hyperthyroidism
• /ften precipitated by infection, surgery, or deli!ery
• +igh fe!ers, tachycardia with associated high mortality
HYPERTHYROIDISM
&a'oratory studies• *le!ated total %( and %)
• *le!ated %) resin upta$e
• *le!ated radioacti!e iodine upta$e• 'ow %S+
HYPERTHYROIDISM
Treatment• ntithyroid drugs• "ethimaole and propylthiouracil 0#%1
o Decrease the synthesis of thyroid hormone by inhibiting the
oxidation of iodideo #% also inhibits the con!ersion of %( to %)
o S$in rash, :oint pain, or agranulocytosis may occur
HYPERTHYROIDISM
Treatment• "ethimaole and propylthiouracil 0#%1o llows out-patient therapy
o 'ess li$elihood of subse;uent hypothyroidism
• Beta-bloc$ers& do not affect thyroid function but will bloc$ adrenergic effects
of hyperthyroidism
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HYPERTHYROIDISM
Treatment• Subtotal thyroidectomy
o llows for cure of hyperthyroidism
o #atient compliance with long-term medication is necessaryo 'ess hypothyroidism than with radioacti!e iodine
o #atient should be euthyroid before surgery
HYPERTHYROIDISM
Treatment• 5adioacti!e iodine
o "ost patients re;uire < or = doses of radioacti!e iodine to cause
decrease in function and sieo llows outpatient treatmento Very high success rate
HYPERTHYROIDISM
Treatment• fter years, up to half of patients may become hypothyroid and re;uire
thyroid hormone replacement• No increase in leu$emia ris$, thyroid cancer, or other malignancies9 slight
ris$ of genetic defects in offspring
HYPERTHYROIDISM
Treatment of tyroid storm• ?V sodium iodide inhibits the release of thyroid hormones
• ntithyroid drugs bloc$ further hormone synthesis
• Beta-bloc$ers bloc$ peripheral effects of thyroid hormone