Subclinical Hypothyroidism in Addison's Disease

Abstract

Fourteen patients with Idiopatic Addison's disease (IAD) were studied in order to detect a possible subclinical hypothyroid state. All were clinically euthyroid with normal serum thyroxine (T4) and serum 3,5′,3′-triiodothyronine (T3). Eleven had circulating thyroid microsomal antibodies in blood. The mean basal serum TSH was significantly higher than that of the control group but only three patients had values above the upper normal range. The mean value of serum T4 was decreased as compared to that of the normal persons, while serum 3,3′,5′-triiodothyronine was elevated. 7.5 mU bovine thyrotrophin per kilogram body weight injected intravenously caused a rise in serum T3 not different from the response in normals. However, as well increasing serum TSH as increasing microsomal antibody titer correlated significantly to decreasing thyroidal release of T3. Our results suggest that clinically euthyroid patients suffering from IAD might have a beginning thyroidal insufficiency because of a progressive immunological damage of the thyroid.

Altered interaction between triiodothyronine and its nuclear receptors in absence of Cortisol: a proposed mechanism for increased thyrotropin secretion in corticosteroid deficiency states

“…The presence of anti-thyroid (micro somes) antibodies has been suggested as a marker of subclinical thyroid hypofunction [15]. Out of the fourteen cases with auto-immune Addison's disease, thyroid antibodies were detected in seven patients.…”

Auto-immune Diseases of the Adrenals, Gonads and Paraythyroids: Auto-immune Polyendocrine Disease

“…They have compared the incidence of such disorders in patients with idiopathic Addison's disease with those suffering from tuberculous adrenal failure. Moreover, there is a high incidence of subclinical hypothyroidism in Addison's disease (McHardy-Young et al 1972;Faber et al 1979;Topliss et al 1980). These disorders include premature ovarian failure, auto-immune thyroid disease, pernicious anaemia, diabetes mellitus, hypoparathyroidism, alopecia totalis or areata, vitiligo, myaesthenia gravis and others.…”

“…These disorders include premature ovarian failure, auto-immune thyroid disease, pernicious anaemia, diabetes mellitus, hypoparathyroidism, alopecia totalis or areata, vitiligo, myaesthenia gravis and others. Faber et al (1979) studied 14 patients with idiopathic Addison's disease in order to detect possible subclinical hypothyroidism. A discussion of associated disorders follows below.…”

“…Similar observations have been made by Doniach and Bottazzo (1981) (see Table 5.2). The prevalence of thyroid microsomal antibodies found in sera from patients with idiopathic Addison's disease and without overt thyroid disease has been found to be between 20% and 79% (Faber et al 1979). Carpenter et al (1964) have reviewed the coexistence of adrenal and thyroid insufficiency, first described by Schmidt (1926) (and termed Schmidt's syndrome).…”