Re: Elaine: Cushings and Hyperthyroid

[Guest guest]

Hi Jae,

I think that Graves' disease can resolve with ATDs nearly always if the

proper dose is used and the drug is continued until the immune system stops

producing TSI. Usually, when ATDs fail, it's a matter of poor monitoring and

withdrawing the meds too soon. Here's what my favorite reference, Werner &

Ingbar's

The Thyroid, 8th edition, says about Cushing's and thyroid disease, " when

replacement doses of a glucocorticoid are given to patients with primary or

secondary hypothyroidism, signs of Cushing's syncrome may appear because of the

hypothyroidism-induced decrease in cortisol clearance. This finding explains the

observation that patients with hypothyroidism are more suxceptible than normal

subjects to the undesirable effects of glucocorticoid therapy. This clinical

state of relative hyperadrenocorticism abates when thyroid hormone is tiven and

the normal rate of metabolism of not only cortisol but also synthetic

glucocorticoids is restored.

Patients with endogenous or exogenous Cushing's syndrome have multiple

abnormalities in pituitary-thyroid function. These changes are more

biochemically evident than clinically important, and they disappear after the

Cushing's

syndrome is treated or the exogenous glucocorticoid is discontinued.

Glucocorticoid excess also may suppress chronic autoimmune thyroiditis, and it

may

become evident as hypothyroidisim or goiter after reversal of the glucocorticoid

excess. In addition, high doses of glucocorticoids ameliorate thyrotoxicosis

in patients with silent thyroiditis or Graves' disease. In summary, the

antiinflammatory or immunosuppressive actions of glucocorticoids can ameliorate

both

thyrotoxicosis and hypothyroidism when the underlying cause is thyroid

autoimmune disease. "

Remember, too, that glucocorticoids cause a false decrease in TSH, which

generally resolves after several weeks, usually before the glucocorticoids are

withdrawn. Glucocorticoids also decrease serum thyroid-binding-globulin (TBG)

concentrations, inhibit conversion of T4 to T3 and cause an increase in the

rental clearance of iodidie.