Corticotropin and cortisol response to maximal exercise testing in central diabetes insipidus

BACKGROUND: It is known that arginine vasopressin (AVP) has a stimulatory effect on corticotropin (adrenocorticotropic hormone; ACTH) and cortisol secretion especially during stress. The present study was designed to investigate the effect of stress on ACTH and cortisol levels in patients with central diabetes insipidus (DI) with endogenous AVP deficiency receiving AVP therapy, and to determine whether these children need steroid replacement during stress. METHODS: Seven patients with a median age of 12 years (range 7-13 years) with idiopathic central DI on appropriate Desmopressin (DDAVP) therapy (group 1) and seven healthy controls with a median age of 15 years (range 13-20 years; group 2) were included in the study. Acute stress was produced in all children by treadmill exercise, assessed by maximal oxygen consumption and heart rate. ACTH and cortisol levels were determined before and after exercise. RESULTS: In group 1, median ACTH level after exercise (28.3 pg/mL) was not different from the median value (24.0 pg/mL) before exercise. However, median cortisol level (10.5 microg/dL) was significantly increased (14.9 microg/dL; P < 0.05) with exercise. In group 2, cortisol (median 9.3 microg/dL) and ACTH levels (median 6.3 pg/mL) were significantly increased after exercise (15 mug/dL and 13.6 pg/mL, respectively; P < 0.05). There was no significant difference between the groups with respect to cortisol levels before and after exercise, but the stimulated ACTH levels after exercise were higher in patients with DI than in the controls (P < 0.05). A positive correlation was observed between total daily DDAVP dose and cortisol level after exercise (r(s)= 0.786, P < 0.05). CONCLUSIONS: Cortisol response during acute stress is normal in children with DI and these patients do not need extra steroid treatment during stress. In contrast, the normal cortisol response obtained by increased ACTH levels in these patients indicates an increased sensitivity of corticotroph cells.     

41Temporary gastric electrical stimulation and the EGG: the SENSA phenomenon.

Introduction: We previously reported that temporary gastric electrical stimulation (GES) is associated with an increase in EGG frequency (IEGGS 2005). We now report further on this phenomenon, which we have labeled Submucosal Enteric Nervous System Activation or SENSA. Patients: We studied 121 patients (18 m, 103 f, mean age 39 years with dx: 71 Idiopathic, 37 diabetes mellitus and 13 post‐surgical disorders) who underwent temporary endoscopic GES. All patients had complete data for baseline cutaneous EGG (Base) and a repeat cutaneous EGG (Temp) after 3 day of temporary GES. Methods: Patients had cutaneous EGGs at baseline and again after temporary GES, performed with high‐frequency, low‐energy stimulation parameters, as previously described (GIE, 2005). Temporary GES mucosal electrode placement was near the submucosal plexus, confirmed by endoscopy. EGGs, performed at a standard time in relation to a low‐fat meal, were reported as average frequency (F, in cpm), were compared by t‐tests with baseline, reported as mean ± SE. Results: For the whole group EGG done with Temporary GES revealed a slight increase in frequency over baseline, but the results were not statistically significant. However, when stratified at baseline as Low (average F < 3.3) or High (≥3.3) a number of differences were present: the patients with Low EEG increased significantly (2.7 (0.1) at Base to 4.5 (0.2) with Temp , p = 0.001) but not for high EGG (4.7 (0.1) to 4.4 (0.1), p = 0.67). See the results detailed in the table below. Conclusion: The occurrence of the phenomena of Submucosal Enteric Nervous System Activation (SENSA) appears dependent on the characteristics of the baseline EGG. As with gastric emptying, careful characterization of baseline values is important when reporting the effects of GES on the EGG. The SENSA phenomena, when occurring, may give important clues to the mechanisms involved in the beneficial effects of temporary gastric electrical stimulation.