Peripheral Metabolism Of Cortisol Research Articles

Increased glucocorticoid production and altered cortisol metabolism in women with mild to moderate Alzheimer’s disease

Background: Abnormalities at several levels of the hypothalamic–pituitary–adrenal axis, which may promote glucocorticoid dependent neurodegeneration, have been reported in patients with Alzheimer’s disease. In this study we have explored the possibility that peripheral cortisol metabolism is enhanced and glucocorticoid production is increased compensatory in patients with mild to moderate Alzheimer’s disease. Methods: Urinary excretion of cortisol and its principal conjugated metabolites was studied in ten women with mild to moderate Alzheimer’s disease, seven healthy elderly women and seven young women. Results: There was an age-related fall in glucocorticoid production (median, 2009 [range 1828–4201] vs. 9315 [range 3613–16,244] μg/24 hours in elderly vs. young control subjects). A-ring metabolism (i.e., the irreversible inactivation of cortisol by 5α- and 5β-reductases) was reduced in old age. However, patients with Alzheimer’s disease showed persistence of cortisol metabolite excretion. Glucocorticoid production was significantly increased in patients with Alzheimer’s disease versus healthy elderly control subjects (median, 7269 [range 6005–15,335] vs. 2009 [range 1828–4201] μg/24 hours), and patients with Alzheimer’s disease had increased A-ring reduction of cortisol. Conclusions: An increased glucocorticoid production is an early feature of Alzheimer’s disease and may be secondary to enhanced metabolic clearance of cortisol by A-ring reduction.

Endogenous inhibitors of 11beta-hydroxysteroid dehydrogenase type 1 do not explain abnormal cortisol metabolism in polycystic ovary syndrome.

The aetiology of enhanced adrenal androgen secretion in polycystic ovary syndrome is poorly understood. Previous reports suggest that enhanced peripheral metabolism of cortisol results in decreased negative feedback suppression of ACTH secretion, either by enhanced inactivation of cortisol by 5alpha-reductase or impaired reactivation of cortisol by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). Endogenous inhibitors of hepatic 11beta-HSD1 can be extracted from urine. We have tested the hypothesis that these are increased in patients with polycystic ovary syndrome. A case-control study. 57 patients with polycystic ovary syndrome and 27 healthy control women. Aliquots from 24 h urine samples were extracted with Sep-Paks and incubated with rat liver microsomes in which 11beta-HSD1 activity was quantified by conversion of 3H-corticosterone to 3H-11-dehydrocorticosterone. Inhibition of 11beta-HSD1 activity was not different in extracts from patients compared with controls (40.8 +/- 18.9 arbitrary units in patients vs. 42.7 +/- 16.6 in controls, mean (+/- SEM, P > 0.60) and did not correlate with ratios of cortisol metabolites in urine or with body mass index. The altered cortisol metabolism in polycystic ovarian syndrome, which is consistent with impaired 11beta-HSD1 activity, cannot be accounted for by increased production of measurable endogenous inhibitors of this enzyme.

Clinical significance of cortisone and cortisone/cortisol ratio in evaluating children with adrenal diseases

Cortisone is derived from the peripheral metabolism of cortisol and lacks biological activity. The rapid interconversion between cortisol and cortisone has been well established. The altered equilibrium between these steroids may regulate glucocorticoid activity in various tissues. We evaluated the serum levels of cortisol and cortisone, and the cortisone/cortisol ratio in ten children with adrenal diseases using reversed-phase high performance liquid chromatography. Children with hypoadrenalism exhibited a greater decrease in cortisol as compared with cortisone. Cortisone levels were higher than cortisol levels, and the cortisone/cortisol ratio exceeded 1.0. Children with adrenal cancer exhibited normal or high values of cortisol, whereas cortisone levels were decreased and the cortisone/cortisol ratio was decreased to nearly zero. The ratio returned to normal after the excision of adrenal tumors. The simultaneous evaluation of cortisol, cortisone, and cortisone/cortisol ratio provides a clinical clue of adrenal diseases.

Liquorice-induced hypertension—a new understanding of an old disease: case report and brief review

The case is described of a 40-year-old female with severe hypertension and hypokalaemic metabolic alkalosis, due to prolonged liquorice ingestion. The pseudo-aldosterone-like effects of liquorice have always been attributed to glycyrrhizic acid, but its biochemical substrate has remained elusive. It is now known that glycyrrhetenic acid, the hydrolytic metabolite of glycerrhizic acid, is the active component of liquorice which causes inhibition of the peripheral metabolism of cortisol. Cortisol binds with the same affinity as aldosterone to the mineralocorticoid receptor resulting in a hypermineralocorticoid condition. Ingestion of liquorice may therefore result in retention of sodium and water, hypertension, hypokalaemia, alkalosis and suppression of the renin-aldosterone system. The literature on liquorice-induced hypertension is briefly reviewed with emphasis on the biochemical features of this mineralocorticoid excess syndrome.

Apparent mineralocorticoid excess type II

The syndrome of apparent mineralocorticoid excess (AME) is currently understood to reflect impaired peripheral metabolism of cortisol, which is then able to activate the non-selective mineralocorticoid (MC) receptor. The failure of glucocorticoid inactivation at the MC target tissue level in AME involves abnormal activity of 11β-hydroxysteroid dehydrogenase, with impaired conversion of cortisol to cortisone, and also of 5β-reductase. We have discovered a new form of AME (Type II) in four patietns with the same clinical picture of hypertension, hypokalemia, and suppressed renin-angiotensin-aldosterone system, but in whom this conversion seems either to be normal (since cortisol to cortisone metabolite ratio is normal) or to be impaired in both directions, leaving the ratio unchanged. Both types are characterized by a profound decrease in cortisol turnover quotient and Ring A reduction constant. Short-term dexamethasone treatment is effective in correcting the MC-derived abnormalities, while in the long term the addition of other antihypertensive drugs may be required to control the severity of hypertension.

Defective ring A reduction of cortisol as the major metabolic error in the syndrome of apparent mineralocorticoid excess.

Impaired peripheral metabolism of cortisol in the syndrome of apparent mineralocorticoid excess is currently understood to be causally related to the severe but otherwise unexplained manifestations of mineralocorticoid excess. A normally ambivalent mineralocorticoid receptor responding equally well to glucocorticoids and mineralocorticoids requires prereceptor inactivation of glucocorticoids to elicit a specific mineralocorticoid effect. The failed inactivation step in the form of the syndrome of apparent mineralocorticoid excess first described (type 1) involves the 11 beta-hydroxydehydrogenation of cortisol to cortisone. In another form of the syndrome (type 2) this conversion occurs normally in the face of otherwise similar clinical and biochemical features. Markedly decreased cortisol metabolic clearance in the type 2 form suggested impairment of a major component of that clearance, ring A reduction. A noninvasive method was developed for measuring the conversion of cortisol to tetrahydrocortisol and allotetrahydrocortisol, and this step was found to be profoundly decreased in both type 1 and type 2 forms. Thus, the major abnormality in the peripheral metabolism of cortisol common to both forms involved ring A reduction, not 11 beta-hydroxydehydrogenation. Since ring A reduction was better correlated with the manifestation of mineralocorticoid excess in both forms of the syndrome, this step might also be a normal major prereceptor mechanism conferring mineralocorticoid specificity.

Two Uncommon Causes of Mineralocorticoid Excess: Syndrome of Apparent Mineralocorticoid Excess and Glucocorticoid-Remediable Aldosteronism

Glucocorticoid-remediable aldosteronism is an inherited form of mineralocorticoid excess associated with moderate overproduction of aldosterone, in which biochemical and clinical remission is dramatically induced by small amounts of glucocorticoids. The disorder is associated with characteristic overproduction of 18-hydroxycortisol and 18-oxocortisol, which must now be regarded as an essential diagnostic feature and also as an aid in the detection of the disorder in the face of partial clinical expression.

20-Dihydroisomers of Cortisol and Cortisone in Human Urine: Excretion Rates under Different Physiological Conditions

The urinary excretion rates of free cortisol and cortisone as well as of their 20-dihydroisomers have been studied in normal subjects under different physiological or pharmacological conditions. For the estimation of steroid excretion rates, a fully automated, liquid-chromatographic method was used. In normal subjects, the median steroid excretion rates of free cortisol, cortisone, 20-alpha-dihydrocortisol, 20-beta-dihydrocortisol, 20-alpha-dihydrocortisone and 20-beta-dihydrocortisone were 6.7, 8.0, 9.8, 5.2, 5.7 and 1.3 mumol/mol creatinine. The excretion rates measured at three different intervals of the day followed a circadian rhythm similar to that known for the cortisol secreting activity of the adrenal gland. After adrenal stimulation by i.v. application of 250 micrograms of tetracosactide hexaacetate, (Synacthen, corticotropin beta 1-24) excretion of urinary cortisol was significantly higher than those of the other steroids. During a 24 h infusion of corticotropin beta 1-24, the excretion rates of cortisol and its C-20 reduced isomers increased to a significantly greater extent than those of cortisone and its C-20 reduced isomers. During a four-hour infusion of hydrocortisone, the relative increase of cortisol excretion was greater than that of the other steroids. During a five-hour infusion of metyrapone at different dosages, the excretion of all steroids decreased in a dose-dependent manner. The present data indicate that the 20-dihydroisomers of cortisol and cortisone in human urine primarily originate from the peripheral metabolism of cortisol rather than from adrenal secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Suppression of Cortisol Secretion by Human Growth Hormone*

The adrenocortical responses to the daily administration of 10 mg human GH (hGH) for 4-6 days were compared in 12 patients with Cushing's disease, 2 patients with cortisol-secreting adrenal cortical adenoma, and 4 healthy subjects. The administration of hGH resulted in a significant mean percent decrease in urinary 17-hydroxycorticosteroids [17OHCS; 30 +/- 7.8 (SE)], cortisol secretion rate (32 +/- 5.5), plasma 17OHCS (31 +/- 5.1), and urinary 17-ketosteroids (46 +/- 6.0) in the patients with Cushing's disease. In contrast, it did not significantly decrease urinary or plasma 17OHCS or the cortisol secretion rate in the other groups of subjects similarly studied. Treatment with hGH did not impair the adrenocortical response to exogenous ACTH, but it decreased the response to metyrapone in all subjects tested. In one of the healthy subjects who had exhibited diminished response to metyrapone on hGH, measurement of plasma ACTH levels demonstrated a lower rise after the administration of the drug. Treatment with hGH did not alter the peripheral metabolism of cortisol, as measured by cortisol turnover rates. We conclude that hGH inhibits ACTH release and that this effect is maximally demonstrated in patients with increased hypothalamic-pituitary-adrenal function.

A Syndrome of Apparent Mineralocorticoid Excess Associated with Defects in the Peripheral Metabolism of Cortisol*

A syndrome is described whose features, suggestive of primary mineralcorticoid excess, included hypertension, hypokalemia, low PRA, and responsiveness to spironolactone. Aldosterone levels were subnormal but as yet there has been no evidence of overproduction of other mineralocorticoids by chemical analysis or by bioassay of plasma and urinary extracts. The steroidal abnormalities that were observed involved peripheral matabolism rather than secretion. One patient exhibited a transient delay in reduction of the 3-keto group in the A ring, and both patients exhibited a decrease in the metabolism of cortisol to biologically inactive cortisone. This was shown by the marked decrease in the excretion of urinary metabolites bearing an 11-keto group and a decrease in the oxidation of 11 alpha-[3H]cortisol to tritiated water. The defect appeared not to be a deficiency of the 11 beta-oxidoreductase system itself, since the reverse reaction of conversion of cortisone to cortisol proceeded normally, but, rater, an alteration in the equilibrium position of 11 beta-oxidoreduction in favor of the reduced form. This was also expressed by a prolongation of the half-time of disappearance of cortisol. The decrease in the MCR permitted the maintenance of normal cortisol plasma levels and normal glucocorticoid function at a diminished rate of secretion. The decreased rate of conversion of cortisol to cortisone serves as a biochemical marker of this hypertensive syndrome.

Adrenal function in the carcinoid syndrome: Effects of the serotonin antagonist cyproheptadine

Results of evaluations of adrenal function in 11 patients with carcinoid tumors are presented. Nine patients had tumors that made and secreted serotonin resulting in elevated 5-hydroxyindoleacetic acid (5-HIAA), elevated serum serotonin, and the carcinoid syndrome; while two patients had tumors that did not make serotonin and that did not cause elevated 5-HIAA excretion or elevated serum serotonin. All of the patients had normal 24-hr 17-hydroxycorticosteroid excretion. In the group of patients with tumors actively secreting serotonin, the correlation between 17-hydroxycorticosteroid and 5-HIAA excretion (r = 0.44) was not significant. Six of these patients pretreated with cyproheptadine (CYPRO), a serotonin antagonist, experienced a 36% mean decrease in 17-hydroxycorticosteroid excretion, a finding that was not present when three of them were treated with triprolidine (TPRO), an antihistamine. Serum cortisol at 8 a.m. was normal in all patients except two whose values were mildly elevated, and these two patients showed evidence of suppression of ACTH secretion secondary to dexamethasone treatment. There was a significant positive correlation between serum-cortisol concentrations and 5-HIAA excretions (r = 0.73, p < .05). Normal diurnal variation was present in six patients in whom it was determined. The serum-cortisol response to insulin-induced hypoglycemia in six patients who had carcinoid tumors actively secreting serotonin was not statistically different from that of 12 normal volunteers. Comparisons between these two groups were difficult because the carcinoid patients' fall in blood sugar was 50%, whereas that of the control group was to 38% of the fasting glucose concentration. Six patients with actively secreting carcinoid tumors responded to standard metyrapone testing with a mean increment of 22.8 ± 2.5 mg/day in 17-hydroxycorticosteroids. This response was statistically different from the increment of 13.8 ± 5.3 mg/day in 17-hydroxycorticosteroid excretion found in 34 agematched hospitalized control patients. When the tests were repeated in four of the patients with carcinoid tumors after pretreatment with CYPRO, the increment in 17-hydroxycorticosteroid excretion was reduced well below the mean increment of the control group. Peak serum 11-deoxycortisol (Compound S) values during the test were also reduced. This decrease in the metyrapone response after CYPRO pretreatment was not due to changed peripheral cortisol metabolism, altered adrenal responsiveness to ACTH, interference with recovery of 17-hydroxysteroids by the Porter-Silber reaction, altered metyrapone metabolism, or reduced renal clearance of Compound S. These changes in adrenal response to metyrapone were not seen when the patients were pretreated with TPRO. Our data suggest that the alterations in adrenal function in our patients may be related to elevated serum serotonin. If CYPRO acts by antagonizing serotonin, these data may give support to the idea of serotoninergic control of cortisol secretion.

Corticosteroids in human blood—VI. Isolation, characterization and quantitation of sulfate conjugated metabolites of cortisol in human plasma

Evidence has been obtained for the presence of a total spectrum of sulfate-conjugated metabolites of cortisol in human plasma: 19 monosulfates, two disulfates and six glucuronosulfates. Two hours and 15 min following i.v. administration of a tracer dose of [4- 14C]-cortisol to 11 normal subjects, large samples of heparinized blood were obtained. From the separated, deproteinized and defatted plasma, all conjugated steroids were extracted by means of an XAD-2 amberlite column. Mono- and di-sulfate conjugated steroids were then separated from other free and conjugated metabolites of cortisol by means of high voltage paper electrophoresis. Individual monosulfate conjugated metabolites and glucuronosulfates were subsequently separated (as seven sub-groups) by paper chromatography. These conjugates were eluted and subjected to cleavage by solvolysis (monosulfates and disulfates) or consecutive solvolysis and β-glucuronidase hydrolysis (glucuronosulfates). The liberated steroid moieties were separated by multiple successive paper chromatographies, and identified by reverse isotope dilution technique. The individual steroids were then quantitated. Sulfate-to-steroid molar ratios were also determined on major conjugates, prior to their cleavage. The steroid metabolites found in plasma are identical with those isolated by us previously from human urine. The total sulfate fraction constituted 5.3 ± 1.9% of all conjugated metabolites of cortisol in plasma. Of those, 76% were monosulfates, 19% were glucuronosulfates, and 5% were disulfates. A large proportion of monosulfates consisted of steroids conjugated at C-21 (27%), which contrasts with glucuronide conjugates. The steroids found in largest concentrations were: 20β-cortolone-3-sulfate (17%), 5α-tetrahydrocortisol-3-sulfate (14%), 6β-hydroxycortisol-21-sulfate (9%), cortisol-21-sulfate (8%), tetrahydrocortisol-3-sulfate (7%), and 20β-dihydrocortisol-21 -sulfate (6%). From the correlation of plasma and urinary concentration of individual steroid sulfates, the following conclusions are drawn: (1) sulfoconjugation is a consistent, though quantitatively minor, pathway in the peripheral metabolism of cortisol; (2) C-21 sulfates of 4-ene-3-oxo-steroids are formed (and excreted) considerably faster than C-3 sulfates, the formation of which requires a prior reduction of ring-A; (3) C-3 sulfates of steroids with dihydroxyacetone side-chain are formed (and excreted) more slowly than the corresponding sulfates of steroids with glycerol side-chain, ergo, the reduction of 20-ketone appears to facilitate sulfoconjugation.

Altered Pathways of Urinary Corticosteroid Excretion in Liver Disease Studied by a Clinical Laboratory Method

Abstract A method of sequential extraction of β-glucuronidase-hydrolyzed urine, which permits the assessment of alternative pathways of corticosteroid excretion, was employed to study urine samples from normal subjects and from patients with hepatic cirrhosis. In patients with hepatic cirrhosis there is a decrease in the excretion of methylene dichloride-soluble 17-hydroxycorticosteroids; this decrease is due to significantly lower levels of tetrahydrocortisone, with moderately low levels of tetrahydrocortisol. A significant increase was observed in the levels of 17-OH,20,21-glycols, confined mainly to cortols in the urine of patients with cirrhosis; a less marked increase in this fraction was also observed in patients with fatty metamorphosis of the liver. Urinary 17-ketosteroids were decreased in patients with hepatic cirrhosis. The intravenous infusion of adrenocorticotropin to normal subjects was followed by increased 17-hydroxycorticosteroids in all solvent fractions of the urine. In patients with hepatic cirrhosis similarly treated, there was no significant rise in the level of 17-hydroxycorticosteroids extracted with methylene dichloride, but significant increases in polar 17-hydroxycorticosteroids were found. The relative magnitudes of the alternate pathways of corticosteroid excretion were determined by calculation of the ratios of (1) total ketols to total glycols, (2) polar ketols to total glycols, and (3) less polar ketols to polar ketols; it was shown that in hepatic cirrhosis there are significant alterations in the excretory pathways of cortisol metabolites, with relative decreases in the excretion as tetrahydrocortisone and increases in the excretion as cortols. Based on these data it is clear that values of routine 17-hydroxycorticosteroid and 17-ketosteroid excretion should be evaluated carefully as to whether they represent abnormal adrenal function or alterations in the peripheral metabolism of cortisol. The method is sufficiently simple to be employed in the clinical laboratory.

Cortisol metabolism in cirrhosis.

The production and peripheral metabolism of cortisol have been studied in 10 cirrhotics and 11 controls after i.v. tracers of cortisol-(14)C. The findings were as follows: (a) Total urinary excretion of radioactivity was normal (81% of the dose) but a decreased fraction was present as glucosiduronates: 18-47% of the dose (average 34%) compared to a normal average of 54%. (b) There was a distinctively abnormal pattern of cortisol metabolites, not previously observed in other illnesses: tetrahydrocortisone was decreased to 14% of the enzyme hydrolysate (normal 26%); cortolones were increased to 34% (normal 19%), owing entirely to an increase in cortolone (20alpha) formation, since beta-cortolone (20beta) was not significantly increased; Reichstein's substances U and epi-U were increased, averaging 2.6% for the former and 4.7% for the latter; tetrahydrocortisol, allotetrahydrocortisol and cortols were normal. This pattern was independent of the degree of decreased glucosiduronate formation and also independent of the presence or absence of a portacaval shunt. (c) Cortisol production, determined by isotope dilution, was normal in each of six cirrhotic patients. From these data, taken in conjunction with our previously reported findings concerning the influence of norethandrolone on cortisol metabolism, the following conclusions were drawn: (a) Cirrhotic patients have decreased A-ring reduction of cortisone to tetrahydrocortisone and correspondingly increased 20-ketone reduction of cortisone to Reichstein's substances U and epi-U and then to the cortolones. (b) Intrahepatic cholestasis, a regular pathophysiological feature of cirrhosis, may be responsible for the observed abnormal cortisol metabolite pattern in this disease. (c) The slowed metabolic turnover rate of cortisol in cirrhosis may be due to decreased transport and/or binding of cortisol to its intracellular metabolic sites rather than to abnormalities of any specific metabolizing enzymes.

EFFECT OF ALTERED THYROID FUNCTION UPON ADRENOCORTICAL ACTH AND METHOPYRAPONE (SU-4885) RESPONSIVENESS IN MAN.

The effect of abnormal thyroid function on the adrenocortical response to ACTH and methopyrapone (Metopirone, Su-4885) infused at different times in the 24 hours has been studied and compared to the response in normal subjects. Hyperthyroidism advanced and exaggerated the normal circadian variation in the adrenocortical response to exogenous ACTH and potentiated adrenocortical activation following Su-4885 when the drug was infused in the early morning. Hypothyroidism produced the opposite effects. Infusion of Su-4885 later in the day demonstrated persistence at both extremes of thyroid function of the circadian variation in the sensitivity of the central nervous system mechanism regulating ACTH release to changes in cortisol concentration. The data are interpreted to suggest 2 independent effects of thyroid hormone upon pituitary ACTH activity: 1) an indirect effect through its influence on the peripheral metabolism of cortisol mediated by the negative feedback mechanism on the magnitude of ACTH secretion, and 2) a direct effect on the central nervous system centers regulating ACTH release. The findings also offer an explanation for the contradictory assessments of pituitary ACTH reserve in patients with altered thyroid function previously reported in the literature.

The influence of plasma protein binding on the extra-adrenal metabolism of cortisol in normal, hyperthyroid and hypothyroid subjects

The role of plasma protein binding in the disappearance of cortisol from plasma in vivo has not been previously studied in normal individuals and those with altered thyroid function. Using an ultracentrifugation technic described herein to measure protein binding, the half-disappearance time of the unbound and protein-bound fractions of plasma cortisol was determined. In 6 normal subjects the mean half-disappearance time of total cortisol from plasma was 134 minutes, while that of its unbound fraction was shorter (81 min.) and that of the bound fraction was longer (163 min.). In hyperthyroid subjects these times were only 53, 40 and 71 minutes, respectively, while in hypothyroidism they were all slowed to 288, 160 and 394 minutes. Unbound cortisol always disappeared from plasma more rapidly than bound. The per cent of total plasma cortisol bound to protein was essentially the same at any given concentration of total plasma cortisol throughout the range (7 to 200 μ g. 100 ml. ) studied, irrespective of the metabolic state. This implied that the association constants and binding capacities of corticosteroid-binding proteins were unchanged in hyper- or hypothyroidism. Therefore, differences in the disappearance of cortisol observed between normal, hyperthyroid, and hypothyroid subjects did not appear to be a function of protein binding, but could be explained solely by alterations in the rate of hepatic and peripheral cortisol metabolism.