Liquid chromatography-tandem mass spectrometry (LC-MS/MS) based assay for the simultaneous quantification of 18-hydroxycorticosterone, 18-hydroxycortisol and 18-oxocortisol in human plasma.

18-hydroxycorticosterone (18-OHB), 18-hydroxycortisol (18-OHF) and 18-oxocortisol (18-OXOF) are important biomarkers for the diagnosis of subtypes of primary aldosteronism. The detection of these three analytes by liquid chromatography-tandem mass spectrometry (LC-MS/MS) is free from structurally similar compounds. The aim of this study was to develop and validate a new LC-MS/MS assay for the simultaneous quantification of 18-OHB, 18-OHF and 18-OXOF in plasma and to establish a reference intervals for apparently healthy population. Plasma samples were prepared by solid phase extraction and separated in an ultra-high performance reversed phase column. MS detection was achieved using a triple quadrupole mass spectrometer in both positive and negative ionization modes. The developed assay was then validated against standard guidelines. We collected 691 plasma samples from apparently healthy individuals (M:398, F:293) to establish the reference intervals. The analytes were separated and quantified within 5 min. The newly developed method demonstrated linearity for the detected steroid concentration in range of 5 to 3000 pg/ml for 18-OXOF (r2 = 0.999) and 20 to 3000 pg/ml for 18-OHB (r2 = 0.997) and 18-OHF (r2 = 0.997). The lower limit of quantification (LLOQ) was 2.5 pg/ml, 20 pg/ml and 20 pg/m for 18-OXOF, 18-OHB and 18-OHF respectively. Specificity, precision, accuracy and stability were tested, and met the requirements of the guidelines. 18-OHB was higher in females than in males, but 18-OHF were higher in males than females. The reference intervals of 18-OHB, 18-OHF and 18-OXOF for both genders together were 90.5-1040.6 pg/ml, 224.4-1685.2 pg/ml, 4.0-70.5 pg/ml, respectively. Age was also an important factor influencing the levels of these three hormones. We have developed a sensitive and reliable method for the simultaneous quantification of 18-OHB, 18-OHF, and 18-OXOF. Our work provides a reference interval for the clinical application of these three steroid hormones.

Enabling insights into the maturation of the renin-angiotensin-aldosterone system in children-Development of a low-volume LC-MS assay for the simultaneous determination of aldosterone, its precursor, and main metabolite.

INTRODUCTION: As part of the renin-angiotensin-aldosterone system (RAAS), aldosterone is key to the pathology of cardiovascular and renal diseases, leading to end-organ damage and cardiovascular death. Because of different aetiology and metabolism, pharmacotherapy in adults shows only limited transferability to children. Comprehensive investigations of humoral parameters, their precursors, and metabolites are necessary to establish a more rational and safe therapy in children. The LENA (Labeling of Enalapril from Neonates up to Adolescents) project aims to generate these missing data in neonates up to adolescents and provide insight into the maturing RAAS. METHODS: A HRMS (high-resolution mass spectrometry) assay was developed, utilizing blank serum depleted of the endogenous aldosterone, its precursor, 18-hydroxycorticosterone, and its main metabolite, tetrahydroaldosterone. A TOF-MS (time-of-flight-mass spectrometry) scan run in parallel with the simultaneous determination of all three analytes enriches the acquired data. Validation of aldosterone was conducted according to EMA and FDA bioanalytical guidelines. RESULTS: Using the Sciex TripleTOF 6600, a reliable determination in 50 µL serum was successfully shown. Appropriate calibration ranges from 19.53 pg/mL for aldosterone, 39.06 pg/mL for 18-hydroxycorticosterone, and 78.13 pg/mL for tetrahydroaldosterone to 2500 pg/mL were established to ensure the applicability in diseased paediatric patients. Between-run accuracy and precision for aldosterone ranged between -1.21 and -6.99 % and 2.07 and -10.22 %, respectively, confirming compliance with international guidelines. CONCLUSION: A simultaneous bioanalytical LC-HRMS assay for the determination of the biomarker aldosterone, its precursor, and main metabolite, utilizing 50 µL serum, was successfully established. This assay facilitates insight into the maturing RAAS from neonates up to adolescents.

Measurement of 18-hydroxycorticosterone during adrenal vein sampling for primary aldosteronism.

CONTEXT: In primary aldosteronism, elevated serum 18-hydroxycorticosterone (18OHB) suggests aldosterone-producing adenoma (APA) rather than bilateral, idiopathic hyperaldosteronism (IHA), but little is known about the relative production of 18OHB and aldosterone (A) in APAs compared with IHA. OBJECTIVES: We measured 18OHB, A, and cortisol (F) in blood from adrenal vein sampling (AVS) studies. We compared the discriminatory power of gradients in 18OHB/A and 18OHB/F ratios with A/F ratio gradients for distinguishing APA from IHA. DESIGN, SETTING, AND SUBJECTS: We measured 18OHB and A in excess serum from 23 AVS studies performed at our university hospitals. MAIN OUTCOME MEASURES: We calculated the ratios 18OHB/A, 18OHB/F, and A/F for all specimens, and determined the adrenal vein gradients for these ratios. RESULTS: The 18OHB/A ratios were much lower in blood draining APAs (2.17 +/- 0.62) than in blood draining the contralateral adrenals (12.96 +/- 12.76; P < 0.001) but similar to blood draining IHA adrenals (4.69 +/- 4.32; P = 0.02). In contrast, the 18OHB/F ratios were elevated in specimens from APAs (26.03 +/- 11.51) compared with IHA adrenals (9.22 +/- 5.18; P < 0.001) or the contralateral adrenals (6.23 +/- 2.97; P < 0.001). Using 18OHB/F gradient greater than two or 18OHB/A gradient less than 0.5 as criteria for lateralization, interpretations agreed with lateralizations based on A/F gradients in 21 of 23 cases. CONCLUSIONS: High serum 18OHB in APA reflects augmented production of both 18OHB and A, not disproportionate 18OHB secretion relative to A. The 18OHB/A and 18OHB/F gradients are useful adjuncts but not as reliable as A/F gradients for A lateralization during AVS.

Responsiveness of plasma 18-hydroxycorticosterone and aldosterone to angiotensin II or corticotropin in nonazotemic diabetes mellitus.

To assess the function of the final step of the pathway for aldosterone biosynthesis, the responsiveness of plasma 18-hydroxycorticosterone and aldosterone concentrations to angiotensin II infusion was studied in 14 patients with nonazotemic diabetes mellitus as compared with 14 normal controls approximately matched for sex and age. In addition, the responses of both steroids to corticotropin injection were investigated in the diabetic patients. Under basal conditions, plasma aldosterone levels were slightly lower in the patients than in normal controls, while plasma 18-hydroxycorticosterone concentrations were similar in the two study groups. Angiotensin II induced marked and comparable increases in plasma 18-hydroxycorticosterone and aldosterone levels in normal and diabetic subjects. Plasma 18-hydroxycorticosterone and aldosterone levels before and after angiotensin II infusion were significantly interrelated; this correlation was similar in normal subjects (r = 0.61; P less than 0.001) and diabetic patients (r = 0.51; P less than 0.005). Plasma 18-hydroxycorticosterone and aldosterone were significantly increased by corticotropin in the patients. These findings indicate that the terminal step of aldosterone biosynthesis, which involves the production of 18-hydroxycorticosterone and aldosterone, is largely unaltered in patients with nonazotemic diabetes mellitus.

Acquired partial corticosterone methyl oxidase type II defect in diabetes mellitus. Case of hyperreninemic hypoaldosteronism.

The aim of this study was to investigate the pathogenesis of hypoaldosteronism in diabetes. Endogenous elevation of plasma renin activity and exogenous corticotropin were used to study steroidogenesis. Observations were made over 12 yr on the evolution and treatment of hyperkalemia in a diabetic subject. In 1977, potassium, baseline cortisol, aldosterone, and renin activity were normal; renin activity increased normally with posture; and cortisol responded normally to ACTH infusion. Nine yr later, persistent hyperkalemia was documented. Upright renin activity was elevated to 5.26 ng.L-1.s-1, with concomitant elevation of 18-hydroxycorticosterone (18-OHB) and a low-normal aldosterone level. One hour after administration of 0.25 mg i.m. cosyntropin, cortisol increased normally, aldosterone increased from 220 to 360 pM, and 18-OHB increased from 3700 to 4800 pM. During treatment with fludrocortisone, fludrocortisone with furosemide, and furosemide alone, improvement of hyperkalemia was noted. Endogenous hyperreninemia and basal elevations of 18-OHB, accompanied by limited aldosterone responsiveness to renin and ACTH, suggest the presence of a partial corticosterone methyl oxidase type II defect. Evolution of hyperkalemia between 1977 and 1986 suggests this defect was acquired.

Effects of metoclopramide on plasma corticosteroid levels in sheep.

This study investigated the role of dopaminergic mechanisms in modulation of corticosteroid secretion in sheep. Administration of the dopamine antagonist metoclopramide (200 micrograms/kg iv) in six mature sheep resulted in rapid and parallel rises in plasma cortisol, corticosterone, 18-hydroxycorticosterone, and aldosterone. Treatment of the sheep with 4 mg dexamethasone im every 6 h for 4 days abolished the response of all four corticosteroids to metoclopramide in the six sheep. These observations suggest that metoclopramide may stimulate corticosteroid secretion in sheep via nonspecific stressor effects.

Dopaminergic modulation of aldosterone secretion in the rhesus monkey: evidence that dopamine affects the late pathway of aldosterone biosynthesis by inhibiting the conversion of corticosterone to 18-hydroxycorticosterone.

This study was designed to investigate the role of dopaminergic mechanisms in the control of aldosterone secretion. Six rhesus monkeys received metoclopramide (1.25 mg, iv), with 5% dextrose (vehicle) or with dopamine (4 micrograms/kg . min) infusions begun 60 min before the administration of the dopamine antagonists. Metoclopramide, in the presence of vehicle, increased plasma aldosterone concentrations from 4.5 +/- 0.5 ng/dl to a maximum of 26 +/- 4.1 ng/dl and PRL concentrations from 8.1 +/- 1.3 ng/ml to a maximum of 118.4 +/- 7.6 ng/ml. Dopamine infusion inhibited the aldosterone and PRL responses to metoclopramide. The administration of metoclopramide resulted in a rise in plasma 18-hydroxycorticosterone from 10.4 +/- 1.5 ng/dl to a maximum concentration of 41 +/- 4.2 ng/dl. The aldosterone and 18-hydroxycorticosterone responses displayed a parallel time course, with significant responses of both occurring 5 min after metoclopramide administration. Plasma concentrations of electrolytes, PRA, plasma cortisol, 11-deoxycorticosterone, corticosterone, and 18-hydroxy-11-deoxycorticosterone were not altered by metoclopramide. The results of this investigation demonstrate that aldosterone and PRL responses to metoclopramide are mediated by their antagonist activities at dopamine receptors. Rather than simply affecting secretion, dopaminergic mechanisms appear to modulate the late pathway of adrenal glomerulosa biosynthesis of aldosterone. A parallel time course of stimulation of 18-hydroxycorticosterone and aldosterone secretion, with no change in other aldosterone precursors, strongly suggests that dopamine modulates the activity of the glomerulosa 18-hydroxylase enzyme.

Mineralocorticoid response to low dose adrenocorticotropin infusion.

The adrenocorticoid responses to low dose ACTH of plasma aldosterone (aldo), corticosterone (B), 11-deoxycorticosterone (DOC), 18-hydroxycorticosterone (18-OHB), 18-hydroxycorticosterone (18-OH-DOC), and cortisol (F) were compared. Alpha ACTH-)1-24) was infused beginning at 0800 h at increasing rates from 12.5-200 mIU/30 min in supine normal subjects under the following conditions: 1) regular Na (120 meq) diet, 2) low Na (10 meq) diet, 3) dexamethasone preadministration (0.5 mg every 6 h for 48 h), and 4) night study (2000 h; 120 meq Na intake). Plasma 18-OH-DOC and B demonstrated quantitatively the greatest responses to ACTH, while DOC and 18-OHB responses were intermediate. Increments in aldo and F were least after ACTH and were maximum at 50 mIU/30 min ACTH, whereas other corticosteroids demonstrated linear responses up to infusion rates of 200 mIU/30 min. All corticosteroids, however, were similar in their threshold responses to ACTH which were at infusion rates of approximately 7-9 mIU/30 min. Na restriction enhanced aldo and 18-OHB responses to ACTH 2- to 3-fold but did not alter the other corticosteroid responses. Dexamethasone pretreatment augmented aldo, 18-OHB, and F responses but did not change the responsitivity of the other corticosteroids to ACTH. Adrenal corticosteroid responses to ACTH were not significantly different between 0800 and 2000 h in subjects on 120-meq Na intake. Thus, corticosteroids show markedly different responses to physiological doses of ACTH, which may have more importance in their regulation than heretofore proposed. Dexamethasone pretreatment enhances aldo, 18-OHB, and F responses to ACTH but does not affect the responses of other corticosteroids. Contrary to reports in experimental animals, corticosteroid responses to ACTH in man do not differ from day to night.

Suppression of adrenal mineralocorticoid production in prehypertensive young adult men.

We assessed the renin-aldosterone axis in response to treadmill exercise and adrenal steroidogenesis after graded ACTH infusions in two groups, each composed of nine young adult men from Bourbon County, Kentucky, from the upper and lower deciles of the blood pressure distribution. Those from the upper decile with relatively higher blood pressures, termed prehypertensive, had significantly lower plasma aldosterone and 18-hydroxycorticosterone concentrations after graded ACTH than those with relatively lower pressures, and had significantly lower urinary potassium excretions. Renin and aldosterone responses to exercise were also significantly blunted in the prehypertensive subjects. No differences were found in plasma cortisol, deoxycortisol, deoxycorticosterone, corticosterone, or dehydroepiandrosterone sulfate, although dehydroepiandrosterone was higher at one infusion rate in prehypertensives. These findings suggest that the adrenal mineralocorticoid pathway and the renin-aldosterone axis are suppressed in prehypertensive young males perhaps as an appropriate feedback response to their higher blood pressures.

Dopaminergic modulation of 18-hydroxycorticosterone secretion in man.

This study was designed to investigate mechanisms of dopaminergic control of corticosteroid secretion and to determine on which step in the aldosterone biosynthetic pathway dopamine exerts its effects. Plasma concentrations of electrolytes, PRA, plasma cortisol, 11-deoxycorticosterone, corticosterone (18-OHB), and 18-hydroxy-11-deoxycorticosterone were not altered by the iv administration of 10 mg metoclopramide in six healthy male volunteers. Metoclopramide increased plasma aldosterone from 6.3 +/- 0.9 ng/dl to a maximum of 23.0 +/- 3.4 ng/dl, plasma 18-OHB from 11.4 +/- 1.1 ng/dl to a maximum level of 42.8 +/- 4.4 ng/dl, and PRL from 9.9 +/- 1.4 ng/ml to a maximum of 71.0 +/- 5.5 ng/ml. The aldosterone and 18-OHB responses displayed a parallel time course, with significant responses of both occurring with 5 min after metoclopramide administration. Dopamine infusions (3 micrograms/kg . min) begun 60 min before the administration of metoclopramide markedly decreased the 18-OHB as well as the aldosterone and PRL responses to the dopamine antagonist. A parallel time course of stimulation of 18-OHB and aldosterone secretion with no change in other aldosterone precursors suggests that dopamine may modulate the activity of the glomerulosa 18-hydroxylase enzyme. Thus, rather than simply affecting aldosterone secretion, dopaminergic mechanisms appear to modulate the biosynthesis of aldosterone.

Dopaminergic control of 18-hydroxycorticosterone responses to posture, isometric exercise, and diuretic administration in normal man.

This study investigates dopaminergic mechanisms involved in the control of corticosteroid secretion in man. The responses of plasma 18-hydroxycorticosterone (18-OHB) and aldosterone levels to upright posture and isometric handgrip exercise and furosemide administration as well as PRA and catecholamine responses to posture and exercise were evaluated in six normal subjects with and without bromocriptine (BEC) treatment. To evaluate the role of PRL suppression by BEC in affecting corticosteroid responses, we evaluated the effect of BEC on plasma 18-OHB and aldosterone responses to 20 mg furosemide in two subjects with autoimmune hypoprolactinemia. BEC (2.5 mg, three times a day for 4 days) markedly suppressed basal levels of 18-OHB, but not aldosterone, in the six normal subjects as well as the two subjects with autoimmune hypoprolactinemia. BEC also suppressed the 18-OHB and aldosterone responses to upright posture, isometric exercise, and furosemide administration without altering electrolytes, PRA, or plasma cortisol levels. Additionally, BEC suppressed basal levels of PRL, norepinephrine, and epinephrine as well as norepinephrine and blood pressure responses to upright posture and isometric exercise in the normal subjects. These results offer additional evidence that dopaminergic mechanisms modulate the secretion of 18-OHB and aldosterone, perhaps indirectly via inhibitory effects of dopaminergic pathways on catecholamine secretion.

The zonal origins of the mineralocorticoid hormones in the 21-hydroxylation deficiency of congenital adrenal hyperplasia.

The 0800 h plasma concentrations of the mineralocorticoid hormones, 18-hydroxydeoxycorticosterone (18-OHDOC), deoxycorticosterone (DOC), corticosterone, 18-hydroxycorticosterone (18-OHB), and aldosterone, in six patients with nonsalt-losing congenital adrenal hyperplasia revealed two groupings of these steroids: in one group, DOC, 18-OHB, and aldosterone were significantly elevated (P less than 0.001) at 51.7 +/- 18.0, 70.8 +/- 14.2, and 22.7 +/- 3.0 ng/dl, respectively; in the other group, corticosterone and 18-OHDOC were normal at 363.6 +/- 76.0 and 7.8 +/- 1.1 ng/dl, respectively. No significant increases in response to upright posture were observed in DOC, 18-OHB, or aldosterone. After a 1-h Cortrosyn stimulation test, the already elevated levels of DOC, 18-OHB, and aldosterone showed slight additional increases, but the normal levels of corticosterone and 18-OHDOC changed little within the normal unstimulated range. In these patients certain mineralocorticoid hormone patterns permit the identification of the zonal origins of steroids. The normal and fixed levels of 18-OHDOC and corticosterone, zona fasciculata steroids, are similar to those of cortisol and imply deficiency of formation and of their precursor, zona fasciculata DOC, a 21-hydroxylated steroid. Both the mineralocorticoid and glucocorticoid pathways distal to 21-hydroxylation are impaired in the zona fasciculata. However, the elevated and partially responsive levels of DOC, 18-OHB, and aldosterone imply that there is greater activation of 21-hydroxylation in the zona glomerulosa than in the zona fasciculata, with its normal fixed steroid levels, and that the elevated level of DOC is primarily from this zone.

Plasma corticosteroid concentrations during spironolactone administration: evidence for adrenal biosynthetic blockade in man.

Spironolactone, a mineralocorticoid antagonist, may also inhibit aldosterone biosynthesis. In vitro studies suggest that spironolactone and its major metabolites inhibit adrenal 18- and 11 beta-hydroxylase activity. We examined various adrenal corticosteroids and their precursors, plasma renin activity, aldosterone excretion rate, and serum and urine electrolytes in normal subjects before and on days 5 and 10 of spironolactone administration (400 mg/day). Plasma corticosteroids were also examined 60 min after ACTH (Cortrosyn) 0.25-mg iv bolus. RIAs were performed after extensive chromatography; there was no interference of spironolactone and its metabolites in the assays. All studies were performed in supine subjects in metabolic balance on a constant 120-meq sodium intake. Plasma renin activity was increased (P less than 0.001) on both days 5 and 10 of spironolactone. Plasma aldosterone (PA) and the aldosterone excretion rate increased (P less than 0.01) on day 5 of spironolactone but decreased (P less than 0.01) from day 5 to 10. Both 11-deoxycorticosterone and 18-hydroxycorticosterone were increased from day 5 to 10. Corticosterone, progesterone, and dehydroepiandrosterone did not increase significantly during spironolactone administration. Incremental PA response to ACTH was less than control on day 10 of spironolactone, but other corticosteroid responses to ACTH were not different during control and days 5 or 10 of treatment. Reduction in PA and further elevation in its precursors during the second 5-day period of spironolactone therapy suggests inhibition of aldosterone biosynthesis during this phase of treatment in normal man. The disproportionate increments in 18-hydroxycorticosterone and 11-deoxycorticosterone suggest biosynthetic inhibition at the 18-dehydrogenase and 11 beta-hydroxylase sites.

Effect of domperidone, an extracerebral inhibitor of dopamine receptors, on thyrotropin, prolactin, renin, aldosterone, and 18-hydroxycorticosterone secretion in man.

This study investigates the dopaminergic mechanisms involved in the control of corticosteroid secretion in normal subjects. TSH, PRL, PRA, aldosterone, and 18-hydroxycorticosterone (18-OHB) were measured before and after the administration of domperidone (10 mg, iv) to eight healthy males. Domperidone, a selective peripheral dopamine antagonist, stimulated TSH and PRL secretion. Plasma concentrations of aldosterone, 18-OHB, cortisol, and PRA were not altered by domperidone. This is in contrast to previous observations of aldosterone, 18-OHB, and PRA responses to metoclopramide, a dopamine antagonist which readily crosses the blood-brain barrier. Domperidone may fail to stimulate aldosterone, 18-OHB, and renin secretion because it does not cross the blood-brain barrier or does not function as an antagonist for adrenal dopamine receptors modulating 18-OHB and aldosterone secretion.

Response of aldosterone and 18-hydroxycorticosterone to angiotensin II in normal subjects and patients with essential hypertension, Conn's syndrome, and nontumorous hyperaldosteronism.

Dose-response curves relating plasma angiotensin II (AII) concentration during AII infusion to blood pressure (BP), to plasma aldosterone, and to plasma 18-hydroxycorticosterone were compared in normal subjects and in patients with essential hypertension, Conn's syndrome, and nontumorous hyperaldosteronism. The BP response was steeper than normal in patients with Conn's syndrome and essential hypertension. Before infusion, mean plasma aldosterone concentration was approximately four-fold higher in Conn's syndrome than in the normal group, while that of 18-hydroxycorticosterone was ninefold higher. Neither increased significantly during AII infusion. In essential hypertension, both corticosteroids were within the normal range, but their responses to AII infusion were greater than normal. In the three subjects with non-tumorous hyperaldosteronism, plasma aldosterone and 18-hydroxycorticosterone concentrations were raised, and their responses to AII infusion resembled those found in essential hypertension and were different from those found in Conn's syndrome. This suggests that nontumorous hyperaldosteronism is not a variant of Conn's syndrome. In the response to AII and in other ways, it is indistinguishable from essential hypertension.

Type 1 aldosterone synthase deficiency presenting in a middle-aged man.

Aldosterone synthase deficiency due to mutations in the CYP11B2 gene usually presents in infancy with electrolyte abnormalities and failure to thrive, whereas affected adults are usually asymptomatic. We describe a patient who first came to medical attention in middle age when he developed hyperkalemia after preparation for a barium enema. Past medical history was notable for failure to thrive in infancy. He had elevated PRA with low serum and urinary levels of aldosterone and its metabolites and normal or slightly elevated levels of 18-hydroxycorticosterone. These findings suggested a diagnosis of type 1 aldosterone synthase deficiency. The patient had a homozygous duplication of six nucleotides at codon 143 in exon 3 of CYP11B2, leading to the insertion of two amino acid residues (Arg-Leu). When the corresponding mutant complementary DNA was expressed in cultured cells, the resulting enzyme was completely inactive, confirming the diagnosis. We conclude that aldosterone synthase deficiency represents an unusual cause of hyperreninemic hypoaldosteronism presenting in adult life, but it should be suspected if the past medical history is positive for failure to thrive in childhood or if the patient manifests no other recognized causes of hyperreninemic hypoaldosteronism.

Effects of continued adrenocorticotropin stimulation on the mineralocorticoid hormones in classical and nonclassical simple virilizing types of 21-hydroxylase deficiency.

Superphysiological doses of ACTH were administered for 3 consecutive days to nine patients with CAH, five with the classical simple virilizing (CSV) type and four with nonclassical simple virilizing type (NCSV; late onset), receiving a sodium-restricted diet. In the CSV patients, cortisol levels were lower [4.9 +/- 2.2 (+/- SEM) micrograms/dl] than in the NCSV patients (10.9 +/- 3.8; P less than 0.005) and normal subjects (10.7 +/- 4.0; P less than 0.05). ACTH produced a subnormal increase to only 14.5 micrograms/dl by day 3. In the NCSV patients, cortisol rose slowly during the first 24 h, but reached normal response levels by 48 h (42.5 +/- 11.5 micrograms/dl). In all patients, basal plasma corticosterone and 18-hydroxydeoxycorticosterone (18-OHDOC) levels were normal, but deoxycorticosterone (DOC) was elevated at 25.3 +/- 5.0 ng/dl (P less than 0.05). ACTH failed to increase plasma levels of DOC, corticosterone, and 18-OHDOC. Aldosterone and 18-hydroxycortisol were elevated in both groups [29.1 +/- 5.8 (P less than 0.02) and 83.8 +/- 15.3 (P less than 0.01) ng/dl, respectively] and increased briskly after the first 24 h of ACTH. However, neither steroid returned to normal levels in the CSV group, but both did in the NCSV group. Paired values of stimulated cortisol and aldosterone in normal subjects and CSV and NCSV patients (n = 76) were significantly negatively correlated (r = -0.63; P less than 0.001), suggesting that cortisol inhibits aldosterone biosynthesis. Prolonged ACTH administration after initial increases returned aldosterone and 18-hydroxycortisol levels from the zona glomerulosa to baseline values in the NCSV type, but not in the CSV type. The capacity to increase cortisol levels, which occurred only in NCSV patients, is linked to the reduction of aldosterone in the zona glomerulosa. In contrast, in both types of 21-hydroxylase deficiency, sustained impairment of both the 17-hydroxy pathway (cortisol) and the 17-deoxy pathway of the zona fasciculata (DOC, corticosterone, and 18-OHDOC) was demonstrated.

Studies of renin activation and regulation of aldosterone and 18-hydroxycorticosterone biosynthesis in hyporeninemic hypoaldosteronism.

In an attempt to evaluate deficiencies of renin activation and adrenal zona glomerulosa biosynthesis in hyporeninemic hypoaldosteronism (HH), we studied active and inactive renin (AR and IR, respectively) responses to the dopamine antagonist metoclopramide, furosemide, and graded dose infusion of ACTH in 10 HH patients and 6 normal subjects. In HH patients, AR levels, but not IR levels, were decreased relative to normal values. While normal subjects had an AR response to metoclopramide, the HH patients did not. The AR response to furosemide in HH patients was markedly diminished compared to that in normal subjects. Plasma cortisol and corticosterone levels were in the normal range, but the zona glomerulosa products 18-hydroxycorticosterone (18-OHB) and aldosterone (Aldo) were low in HH patients. Plasma 18-OHB and Aldo responses to metoclopramide and furosemide were diminished, but cortisol and 18-OHB responses to ACTH were normal in the HH patients. Our observation that 18-OHB and Aldo responses to metoclopramide were diminished refutes the possibility that excessive adrenal zona glomerulosa dopaminergic activity could account for reduced biosynthesis of 18-OHB and Aldo in HH patients. Our results appear most consistent with the concept that the primary etiological factor in the HH syndrome is impairment of renal activation of renin.

Plasma corticosteroids in hyperreninemic hypoaldosteronism: evidence for diffuse impairment of the zona glomerulosa.

A subgroup of critically ill patients with selective hypoaldosteronism despite hyperreninemia has recently been defined. The mechanism underlying the subnormal response of aldosterone secretion is poorly understood. As cortisol secretion remains intact and the condition usually follows hypotensive episodes, ischemic or functional impairment restricted to the adrenal glomerulosa may be involved. To evaluate the possibility that a specific biosynthetic pathway deficiency exists in hyperreninemic hypoaldosteronism (HH), basal and ACTH-stimulated levels of aldosterone and its immediate precursors 18-hydroxycorticosterone (18-OHB) and corticosterone (B) were determined in eight HH patients, six critically ill subjects with normal aldosterone responsiveness, and nine healthy subjects. Baseline aldosterone (8.2 +/- 3.2 vs. 44.7 +/- 23.6 ng/dl) and 18-OHB (44.7 +/- 13.6 vs. 547.6 +/- 300.4 ng/dl) were lower in HH patients than in Intensive Care Unit controls (both P less than 0.01) despite similarly increased renin concentration and activity. ACTH-stimulated aldosterone and 18-OHB were significantly lower in HH patients, although the percent increase was similar to Intensive Care Unit controls. Plasma B was also lower in HH patients, though not significantly. After ACTH, B was markedly lower than both ICU controls (1764 +/- 576 vs. 6299 +/- 1266 ng/dl, P less than 0.01) and healthy controls (3261 +/- 248 ng/dl, P less than 0.01). All groups had appropriate cortisol responses demonstrating normal zona fasciculata function. Since 18-OHB arises predominantly from the zona glomerulosa, whereas B also derives in part from the zona fasciculata, the data suggest generalized impairment of the adrenal zona glomerulosa probably affecting both early and late pathway corticosteroid biosynthesis.