Studies in Cushing's syndrome. III. Urinary 17-ketosteroids in patients with bilateral adrenal cortical hyperplasia

Mineralocorticoid excess and inhibition of 11 beta-hydroxysteroid dehydrogenase in patients with ectopic ACTH syndrome

OBJECTIVE

11 beta-Hydroxysteroid dehydrogenase protects renal mineralocorticoid receptors from cortisol by converting cortisol to inactive cortisone. We hypothesize that 11 beta-dehydrogenase is inhibited by ACTH, providing a mechanism whereby cortisol induces hypokalaemic alkalosis in ectopic ACTH syndrome.

DESIGN/MEASUREMENTS

The principal sources of plasma cortisone were assessed by selective venous catheterization with measurement of cortisol and cortisone by radioimmunoassays. The effect of ACTH on peripheral plasma cortisol/cortisone ratio was assessed in healthy volunteers during circadian rhythm, insulin induced hypoglycaemia, and infusions with exogenous ACTH or cortisol. In patients with Cushing's syndrome plasma cortisol/cortisone ratios were related to plasma potassium, corticosterone, and 11-deoxycorticosterone concentrations.

PATIENTS

Catheterization was performed in 24 patients with valvular or ischaemic heart disease. Cushing's syndrome patients included: 15 with pituitary adenoma; two with adrenal adenoma; and nine with ectopic ACTH secretion.

RESULTS

Plasma cortisol/cortisone ratios were low in renal vein and high in hepatic vein. In healthy volunteers plasma cortisone increased during cortisol infusion but did not change with increases in endogenous or exogenous ACTH. Plasma cortisol/cortisone ratios were higher in ectopic ACTH syndrome than in other forms of Cushing's syndrome. However, the cortisol/cortisone ratio was no better a predictor of hypokalaemia than the levels of 11-deoxycorticosterone or corticosterone.

CONCLUSIONS

Peripheral conversion of cortisol to cortisone occurs mainly in the kidney and is inhibited by ACTH. In ectopic ACTH syndrome the characteristic mineralocorticoid excess can be accounted for by a combination of increased secretion of cortisol, corticosterone and of 11-deoxycorticosterone and decreased inactivation of cortisol and corticosterone by 11 beta-dehydrogenase.

Adrenocortical carcinoma with Cushing's syndrome presenting unusual urinary 17-ketosteroid fractionation

A case of adrenal carcinoma with Cushing's syndrome was presented. Endocrinological and morphological investigations disclosed the presence of a functional adrenal carcinoma. This case was characterized by its unusual urinary 17-ketosteroid (17-KS) fractionation, i.e. a marked elevation of 17-KS was accompanied by the increments of etiocholanolone, but not of dehydroepiandrosterone (DHEA) or androsterone. Measurements of the plasma adrenocorticosteroids revealed normal DHEA and DHEA-S (sulfate) levels, moderately increased 17-OH-pregnenolone, and markedly increased (less than 100 times the normal) 11-deoxycortisol (cpd S). Therefore, it seems plausible that the normal urinary DHEA level in this patient would have occurred as a result of remarkably low C17-20 lyase activity sufficient to hamper DHEA production, and that markedly increased etiocholanolone might possibly have been converted from cpd S as well as from DHEA and androstenedione through 5 beta-reduction.

Investigation of urinary steroid profiles as a diagnostic method in Cushing's syndrome

Patients with Cushing's syndrome may be discriminated from normal subjects on the basis of their respective neutral urinary steroid profile. In the former group, evidence is presented that lowered levels of T3 secondary to hypercortisolism, decrease the liver enzymes associated with 5 alpha-reductase and 11 beta-hydroxy steroid dehydrogenase activity. As a result the metabolism of cortisol and androstenedione in Cushing's syndrome yields a unique pattern dominated by 5 beta and 11 beta-hydroxy steroid metabolites.

The indirect analysis of 17-oxosteroid glucosiduronates and sulphates in human urine

1. An analytical procedure has been developed for the determination of urinary 17-oxosteroid sulphates and 11-deoxy-17-oxosteroid glucosiduronates. 2. By submitting urine to the following operations: (a) extraction of the 17-oxosteroid conjugates into chloroform (in the presence of pyridinium sulphate), (b) solvolysis (in the absence of acid) of the steroid sulphates, (c) separation of the steroid glucosiduronates, (d) hydrolysis of the glucosiduronates, (e) oxidation with tert.-butyl chromate of the liberated steroids and (f) analysis of the final extracts by gas-liquid chromatography, the 17-oxosteroid conjugates are converted into and measured as androstanediones and androstane-(ene)triones. 3. Values for the daily excretion of 17-oxosteroid glucosiduronates and sulphates in normal men and women are given.