Abstract
We present three cases of isolated adrenocorticotropin (ACTH) deficiency accompanied by derangement of the thyroid-stimulating hormone (TSH)-thyroidal axis. Thyroid hormone and TSH levels were evaluated before and after cortisol replacement. Although markedly elevated levels of TSH were noted in one case, this patient also showed typical features of Hashimoto’s thyroiditis. In the other two cases, basal TSH levels were increased, and replacement of cortisol reversed the values. We have previously reported that interference of thyroid hormone synthesis and/or secretion by glucocorticoid deficiency is a major cause of TSH-thyroidal axis derangement. However, it has been shown that a considerable number of reported cases exhibit severe hypothyroidism due to Hashimoto’s thyroiditis, as was shown in case 2. It has been recognized that, whether the origin is the pituitary or the adrenal gland, polyglandular failure is a complex of autoimmune endocrinopathy. Alternatively, it is assumed that depletion of the physiological concentration of cortisol may worsen hypothyroidism due to Hashimoto’s thyroiditis, possibly through modification of T cell function. Since transient abnormalities of the TSH-thyroidal axis and growth hormone could occur in glucocorticoid-deficient patients along with derangement of other pituitary hormones, hormonal evaluation should be carried out after a sufficiently long interval following cortisol replacement.
