Hyperthyroidism and Thyroid Storm

Posted by e-Medical PPT
Normal Thyroid State
Synthesis and release of thyroid hormone is controlled by TSH relaesed form the anterior pituitary
TSH is controlled by the release of thyroid releasing hormone (TRH) from the hypothalmus and a negative feedback loop to the pituitary
Thyroid hormone production s dependent on adequate adequate iodine intake
Thyroid hormone is reversible bound to various proteins including thyronine-binding globulin (TBG)
Free unbound portions are biologically active
T4 is the predominant circulating hormone
T4 is deiodinated to t3
T3 is biologically more active than T4 but has a shorter half-life

Hyperthyroidism
Occurs in in all ages
Uncommon under the age of 15
10 x’s more common in women (1/10,000)
Graves disease is the most common etiology
 80% of cases in the U.S.
 Common in the 3rd and 4th decades
 Caused by autoimmune thyroid-stimulating antibodies
 Associated with diffuse goiter, opthalmopathy, and local dermopathy

Toxic multinodular and toxic nodular goiters are the next most common etiologies
 Usually occurs in older populations   
 Commonly with previous history of goiter
 Often with milder symptoms of thyrotoxicosis

Amiodarone-induced thyrotoxicosis (AIT)
Amiodarone is iodine rich and may cause both hyper and hypothyroidism
Difficult to treat because of incomplete understanding of mechanism
Two major forms exists
 Type 1 occurs with a normal thyroid
 Type 2 occurs with a abnormal thyroid
Tx. Varies based on the the type

Confirmed by thyroid function test
 Elevated free T4 and Low TSH
 In some cases of graves disease T4 may be normal and TSH decreased but the patient appears thyrotoxic
 T3 level should be done to rule out T3 toxicosis
 Hypothyroidism secondary to pituitary adenoma will have elevated TSH levels

Thyroid Storm
A life threatening hypremetabolic state due to hyperthyroidism
Mortality rate is high (10-75%) despite treatment
Usually occurs as a result of previously unrecognized or poorly treated hyperthyroidism
Thyroid hormone levels do not help to differentiate between uncomplicated hyperthyroidism and thyroid storm

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