Corticotrope hypersecretion coupled with cortisol hypo-responsiveness to stimuli is present in patients with autoimmune endocrine diseases: evidence for subclinical primary hypoadrenalism?
OBJECTIVE
In autoimmune polyglandular syndrome types 1, 2, and 4 primary adrenal insufficiency is present, but its diagnosis is often late. We investigated the function of the hypothalamic-pituitary-adrenal axis in a group of patients with autoimmune diseases (AP) without any symptoms and signs of hypoadrenalism.


METHODS
In 10 AP and 12 normal subjects (NS), we studied cortisol (F), aldosterone (A), and DHEA responses to 0.06 microg adrenocorticotropin (ACTH) (1-24) followed by 250 microg, ACTH and F responses to human corticotropin-releasing hormone (hCRH; 100 microg) and insulin tolerance test (ITT) (0.1 UI/kg).


RESULTS
Basal F, A, DHEA, as well as urinary free cortisol and plasma renin activity levels in AP and NS were similar, whereas ACTH levels in AP were higher (P<0.05) than in NS. NS showed F, A, and DHEA response to both consecutive ACTH doses. In AP, the F, A, and DHEA responses to 250 microg ACTH were similar to those in NS, whereas the 0.06 microg ACTH dose did not elicit any significant response. The ACTH responses to hCRH and ITT in AP were higher (P<0.05) than in NS. The F response to hCRH in AP was lower (P<0.05) than in NS, whereas the F response to ITT in AP did not significantly differ from NS.


CONCLUSIONS
Enhancement of both basal and stimulated corticotrope secretion coupled with reduced adrenal sensitivity to low ACTH dose is present in AP patients without symptoms and signs of hypoadrenalism. This functional picture suggests that normal adrenal secretion is maintained due to corticotrope hyperfunction, suggesting the existence of some subclinical primary hypoadrenalism.
Giordano
Roberta
R
Department of Internal Medicine, Division of Endocrinology and Metabolism, University of Turin, Ospedale Molinette, C.so Dogliotti 14 10126 Turin, Italy.
Balbo
Marcella
M
Picu
Andreea
A
Bonelli
Lorenza
L
Berardelli
Rita
R
Falorni
Alberto
A
Ghigo
Ezio
E
Arvat
Emanuela
E
D000309:Adrenal Insufficiency / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone / Q000009:adverse effects / Q000097:blood / Q000378:metabolism*; D000328:Adult; D000450:Aldosterone / Q000097:blood; D019540:Area Under Curve; D001323:Autoantibodies / Q000032:analysis; D001327:Autoimmune Diseases / Q000378:metabolism*; D003687:Dehydroepiandrosterone / Q000097:blood; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood / Q000502:physiology* / Q000652:urine; D008297:Male; D008875:Middle Aged; D012083:Renin / Q000097:blood
D001323:Autoantibodies; D003687:Dehydroepiandrosterone; D000450:Aldosterone; D000324:Adrenocorticotropic Hormone; D012083:Renin; D006854:Hydrocortisone