PubMed · 5902156
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M Arslan. 1966. Ultrasonic hypophysectomy.. https://doi.org/10.1017/s0022215100064975
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The effects of somatostatin and its analogs have been studied in different subclasses of patients with Cushing's syndrome (due to Cushing's disease, ectopic corticotropin [ACTH]- and/or corticotropin-releasing hormone [CRH]-secreting tumors, or ACTH-independent Cushing's syndrome) and in patients with Nelson's syndrome. In most patients with untreated Cushing's disease, octreotide does not suppress ACTH release, a finding that is supported by in vitro studies. However, octreotide or somatostatin inhibits pathological ACTH secretion in Nelson's syndrome. Short-term octreotide treatment has caused a significant initial response (decreased serum cortisol, ACTH, and cortisoluria) in 24 of 38 (64%) patients with ectopic ACTH/CRH Cushing's syndrome, and long-term treatment caused a persistent response in 10 of 14 (71%) cases. Pentetreotide scintigraphy may help to identify those patients with ectopic ACTH/CRH tumors who will have an initial response to octreotide, and is useful for locating ectopic ACTH/CRH-secreting tumors and their metastases. To date, octreotide has been shown to temporarily suppress gastric inhibitory peptide (GIP)-induced cortisol secretion in GIP-dependent (ACTH-independent) Cushing's syndrome, but has not shown any therapeutic benefit in other forms of ACTH-independent Cushing's syndrome.
The best long-term results of transsphenoidal surgery appear to be in those patients who have unmeasurable serum cortisol levels in the immediate post-operative period. This appears to be due to isolated ACTH deficiency in the remaining normal pituitary gland. In our experience, however, long-term clinical remission may be possible with measurable serum cortisol levels post-operatively. The cortisol response to ACTH or CRF appears to provide no greater discrimination than basal measurements and is possibly less helpful than dexamethasone suppression. The prolonged clinical remission that we have seen in some patients with early measurable but low cortisol levels, together with the possible operative morbidity and partial success of repeat surgery, suggests careful assessment before a recommendation is made of an immediate second operation in these patients. The possibility of cyclical secretion of cortisol must be considered both pre and post-operatively. Finally, as experience with transsphenoidal surgery is still relatively short, all these patients need continuing endocrine follow-up in centres with adequate experience of the condition. For the individual patient we recommend that decisions regarding further therapy are based on 0800-0900 h serum cortisol levels, an index of cortisol production (serum cortisol day profiles or 24 hour urinary free cortisol), and the response to low dose dexamethasone suppression in the early post-operative period.
OBJECTIVE: There is no endocrine test which is completely reliable for the confirmation of Cushing's syndrome and in separation of the various aetiologies. We have tested the hypothesis that overnight dexamethasone pre-treatment should result in a better performance of the lysine-vasopressin (LVP) test in the diagnosis of Cushing's syndrome. STUDY DESIGN AND PATIENTS: We studied 61 subjects, including 25 pituitary-dependent and 9 pituitary independent Cushing's (7 adrenal tumour and 2 ectopic ACTH syndromes), 18 euadrenal controls, 4 depressed subjects, and 5 cushingoid patients. The subjects received 1 mg of dexamethasone orally at 2300 h and the following morning they were given 10 IU of lysine-vasopressin im. MEASUREMENTS: Plasma cortisol (RIA) was measured at times -15, 0, 15, 30, 45, 60, 75, 90 and 120 minutes. RESULTS: The dexamethasone-modified LVP (Dx/LVP) test resulted in four patterns of cortisol response. The dexa sensitive pattern (positive suppression and negative response to LVP) was found in euadrenal subjects; the dexa insensitive pattern (negative suppression and positive response to LVP) was seen in Cushing's disease; a non-responsive pattern (negative suppression and negative response to LVP) was observed only in pituitary independent Cushing's; and an indeterminate pattern (positive suppression and positive response to LVP) was equivocal, being observed in 2 control subjects, 1 patient with Cushing's disease and 1 depressed patient. In separating control subjects from Cushing's syndromes the Dx/LVP test had 88.9% sensitivity, 100% specificity and 96.2% diagnostic accuracy; when the test was used to segregate Cushing's disease from control subjects we found 96.0% sensitivity, 100% specificity and 97.7% diagnostic accuracy. The performance variables for the Dx/LVP test in separating pituitary dependent from pituitary independent Cushing's were uniformly 100%. Depressed and cushingoid subjects did not differ from control subjects in their cortisol patterns during the test. Successful removal of the pituitary microadenoma in Cushing's disease was invariably followed by a reversal of the abnormal cortisol pattern (dexa insensitive) during the test to a dexa sensitive pattern indistinguishable from that of control subjects. CONCLUSION: These results confirm our hypothesis and suggest that an improved performance of any corticotroph stimulus (oCRH, LVP, AVP or desmopressin) in the diagnosis of Cushing's syndrome should result from pre-treatment with dexamethasone.