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ACTH ‐secreting pituitary microadenomas are associated with a higher prevalence of central hypothyroidism compared to other microadenoma types
Author(s) -
Mathioudakis Nestoras,
Thapa Sritika,
Wand Gary S.,
Salvatori Roberto
Publication year - 2012
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.2012.04442.x
Subject(s) - medicine , endocrinology , hypopituitarism , adrenocorticotropic hormone , glucocorticoid , prolactin , pituitary adenoma , pituitary disease , adenoma , hormone
Summary Context Unlike pituitary macroadenomas, microadenomas (micros) are not commonly associated with hypopituitarism. In clinical practice, we have observed that patients with ACTH ‐secreting micros have a higher than expected prevalence of central hypothyroidism ( HT ), and we speculated that this effect might be because of glucocorticoid‐induced suppression of the hypothalamic–pituitary–thyroid axis. Objective To determine whether there is a difference in the prevalence of central HT among ACTH micros compared to other types of microadenoma, and if so, to investigate whether this is directly related to the degree of hypercortisolism. Design, setting and patients Retrospective study of 149 newly diagnosed patients with pituitary micros: 34 ACTH ‐secreting, 72 prolactin‐secreting ( PRL omas) and 43 clinically nonfunctioning adenomas ( NFA s). Main outcomes measures Prevalence of central HT , correlation between normalized free T 4 or TSH vs normalized urinary free cortisol ( UFC ) or salivary cortisol. Results The prevalence of central HT was significantly higher in the ACTH compared to the non‐ ACTH adenomas: 18% ( ACTH ), 1% ( PRL ) and 0% ( NFA s). The mean normalized free T 4 was lower in the ACTH micros compared to the non‐ ACTH micros (1·29 ± 0·06 vs 1·50 ± 0·23, P = 0·0001). There was no correlation between the degree of hypercortisolism, as reflected by 24‐h urine free cortisol and salivary cortisol, and free T 4 or TSH levels among the ACTH adenomas. Similarly, there were no differences in mean UFC or salivary cortisol between ACTH adenomas with and without central HT . Following transsphenoidal adenomectomy, central HT recovered in three of six patients with ACTH micros. Conclusions These findings suggest that patients with ACTH ‐secreting microadenomas should always, at a minimum, undergo testing for central HT . However, given the potential for recovery of thyroid function following cure of C ushing disease, we recommend withholding thyroid hormone replacement until after pituitary surgery.