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Several studies have demonstrated that the corticotropin-releasing factor test (CRF) is useful for the aetiological diagnosis of Cushing's syndrome: in Cushing's disease, as opposed to ectopic ACTH secretion syndrome, the hypothalamus-pituitary-adrenal (HPA) axis can still be stimulated by CRF. In the present study, we compared the CRF test with the reinforced dexamethasone suppression test in 18 patients: 11 with Cushing's disease, 6 with ectopic ACTH secretion and 1 with adrenal gland adenoma. We obtained 2 false-negative results with the CRF test and 1 false-positive result with the dexamethasone suppression test. Our study, together with published data, suggests that the CRF test is useful in the exploration of Cushing's syndromes of uncertain origin. However, the results obtained with this test must be compared with those of other methods used to explore the HPA axis and which are still necessary.

In order to check the long-term tolerance of a laxative treatment, the authors supervised during six months a group of 14 elderly people (12 women and 2 men) with a mean age of 81.3 years suffering from long-standing constipation without any organic cause. The laxative was given in a daily dosage corresponding to 20 mg of sennosides. Alpha 1-antitrypsin (alpha 1-AT) clearance and exchangeable potassium pool (PPE) were measured, at the beginning (T0), and at the end of the third (T3) and the sixth (T6) months of the study. No abnormal variation of intestinal protein loss (alpha 1-AT: T0, 6.74 +/- 3.16; T3, 2.96 +/- 1.35; T6, 4.15 +/- 1.45 ml/24 h; T0-T3; p less than 0.05, T0-T6, T3-T6: NS) and exchangeable potassium pool (PPE: T0, 19.54 +/- 2.55; T3, 20.29 +/- 3.46, T6, 23.56 +/- 4.92 mEq/kg; T0-T3, T0-T6, T3-T6: NS) was observed. In opposition to current views, all long-term laxative treatments do not necessarily induce significant intestinal protein and potassium losses.