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ADRENOCORTICOTROPHIN (ACTH) DEFICIENCY UNDETECTED BY STANDARD DYNAMIC TESTS OF THE HYPOTHALAMIC‐PITUITARY‐ADRENAL AXIS
Author(s) -
TSATSOULIS A.,
SHALET S. M.,
HARRISON J.,
RATCLIFFE W. A.,
BEARDWELL C. G.,
ROBINSON E. L.
Publication year - 1988
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.1365-2265.1988.tb03659.x
Subject(s) - endocrinology , medicine , adrenocorticotropic hormone , acth secretion , hypothalamic–pituitary–adrenal axis , hormone
SUMMARY Six patients (four females, two males; aged 18–65 years), previously treated by external pituitary irradiation (2000–4000 cGY in 8–15 fractions over 10–20 days) for pituitary tumours, presented with the symptoms of excessive and inappropriate tiredness suggestive of ACTH deficiency, despite a normal peak cortisol response to an insulin tolerance test (four cases) or to a glucagon stimulation test (two cases). These six patients were found to have significantly lower mean 24 h urinary free cortisol levels (100 ± 40 nmol; mean ± SD) compared with the mean value of 31 normal controls (210 ± 70.8 nmol; P <0.01). In addition serum cortisol profiles based on a series of four timed samples between 0900–2300 h were subnormal (mean 130 nmol/l) in comparison with profiles obtained from 12 normal controls (mean 270 nmol/l) ( P <0.001). Glucocorticoid replacement therapy promptly abolished their symptoms. These results suggest that a discordance between ACTH secretion under basal circumstances and ACTH response to pharmacological tests may exist in patients with ACTH deficiency. We speculate that defective endogenous corticotrophin‐releasing hormone (CRF) secretion, due to radiation‐induced damage at hypothalamic level, is one cause of this phenomenon.