Plasma levels of corticotropin-releasing hormone in hypothalamic-pituitary-adrenal disorders and chronic renal failure.

Plasma levels of corticotropin-releasing hormone (CRH) were measured in hypothalamic-pituitary-adrenal disorders and chronic renal failure to investigate the clinical significance of plasma CRH. The mean plasma CRH level in normal subjects (N = 26) was 1.64 +/- 0.43 pmol/l (normal range 0.77-2.5 pmol/l). Four of six patients with hypothalamic disorders receiving hydrocortisone supplementation had a low plasma CRH level. Two of six patients with Sheehan's syndrome had a low plasma CRH level whereas one patient had a high plasma CRH level. Two patients with Cushing's syndrome had a low plasma CRH level whereas two patients with Cushing's disease had a normal plasma CRH level. Six of 19 patients receiving prednisolone therapy had a low plasma CRH level. The mean plasma CRH level in this group was 0.97 +/- 0.34 pmol/l, which is significantly lower than that in the normal group. In this group, significant correlation was seen between plasma CRH and adrenocorticotropin levels. Eleven of 21 patients with chronic renal failure undergoing hemodialysis had a high plasma CRH level. Just after hemodialysis the plasma CRH levels decreased in 15 of 20 patients, while plasma adrenocorticotropin and cortisol levels increased in 13 of 19 patients and in 15 of 20 patients, respectively. Immunoreactive CRH in plasma measured both before and after hemodialysis eluted similarly on reversed-phase high-performance liquid chromatography. These results suggest that the plasma CRH level is at least partially suppressed by a chronically elevated plasma glucocorticoid level and that CRH in plasma is partially removed by hemodialysis.