Plasma adrenocorticotropic hormone but not aldosterone is correlated with blood pressure in patients with aldosterone‐producing adenomas

Although plasma aldosterone concentration (PAC) varies depending on primary aldosteronism (PA) subtypes, patients with different subtypes may have similar blood pressure (BP). The authors hypothesized that hormones other than aldosterone might influence BP in PA patients. A total of 73 PA cases, including 30 cases of aldosterone‐producing adenomas (APAs), 29 cases of bilateral hyperaldosteronism, and 24 control cases of essential hypertension were enrolled retrospectively. The authors examined the levels of aldosterone, cortisol, renin, and adrenocorticotropic hormone (ACTH) measured at 12 am , 6 am , 12 pm , and 6 pm and BP in the early morning (6 am to 7 am ), late morning (9 am to 11 am ), and early evening (5 pm to 7 pm ). Results showed no statistically significant correlation between PAC and BP in the patients with PA; however, early and late morning systolic BP strongly correlated with ACTH at 6 am in patients with APA. These results suggest that hormones other than aldosterone, such as ACTH, may affect BP in patients with APA.     

Ambulatory Blood Pressure Monitoring–Derived Short‐Term Blood Pressure Variability in Primary Aldosteronism

The aim of this study was to investigate the short‐term blood pressure (BP) variability (BPV) derived from ambulatory blood pressure monitoring (ABPM) in patients with primary aldosteronism (PA), either idiopathic hyperaldosteronism (IHA) or aldosterone‐producing adenoma (APA), in comparison with patients with essential hypertension (EH) and normotensive (NT) controls. Thirty patients with PA (16 with IHA and 14 with APA), 30 patients with EH, and 30 NT controls, matched for sex, age, body mass index, and antihypertensive therapy, were studied. The standard deviation (SD) of 24‐hour, daytime, and nighttime BP; 24‐hour weighted SD of BP; and 24‐hour BP average real variability were not different between patients with PA and those with EH (P=not significant). All BPV indices were higher in patients with PA, either IHA or APA subtypes, and patients with EH, compared with NT controls (P<.001 to P<.05). ABPM‐derived short‐term BPV is increased in patients with PA, and it may represent an additional cardiovascular risk factor in this disease. The role of aldosterone excess in BPV has to be clarified.     

肾上腺静脉采血在原发性醛固酮增多症分型诊断中的应用

目的探讨肾上腺静脉采血（AVS）检查在原发性醛固酮增多症（原醛症）分型诊断中的应用价值。方法收集瑞金医院近4年来39例临床确诊的原醛症患者[23例特发性醛固酮增多症（特醛症），16例醛固酮瘤]，经肾上腺静脉插管检查，取双侧肾上腺静脉以及肾静脉水平下的下腔静脉血液，测各点醛固酮和皮质醇水平，并将结果与影像学检查、体位激发试验（PST）及术后病理结果进行比较。结果（1）23例特醛症患者体位激发后血醛固酮较基础值均升高；16例醛固酮瘤患者血醛固酮升高者占56．3％（9／16）；（2）特醛症患者肾上腺B超检查符合率为69．6％（16／23），醛固酮瘤患者为56．3％（9／16）；肾上腺CT检查特醛症患者符合率为73．9％（17／23），醛固酮瘤患者为81．3％（13／16）；（3）AVS检查以两侧醛固酮之比作为判定标准时符合率为71．8％，以醛固酮与皮质醇之比为判定标准则达到100％。醛固酮瘤患者生化异常程度较特醛症患者明显。PST在特醛症及醛固酮瘤中有部分重叠；体位激发后血醛固酮升高者不能排除醛固酮瘤，而血醛固酮下降者可诊断为醛固酮瘤。结论单纯依赖影像学检查对于原醛症患者进行分型诊断易发生误诊。AVS检查的准确性高，对于影像学检查未能发现明显占位性病变者须进行该检查以明确诊断；对于AVS结果，用两侧醛固酮与皮质醇的比值之比分析较单纯比较两侧醛固酮之比更为可靠。     

New diagnostic procedure for primary aldosteronism: adrenal venous sampling under adrenocorticotropic hormone and angiotensin II receptor blocker--application to a case of bilateral multiple adrenal microadenomas.

Formerly, the incidence of primary aldosteronism (PA) among patients with hypertension was believed to be less than 1%. However, recent studies have suggested a much higher incidence of 6.59%-14.4% among such patients. These findings suggest that many cases of PA caused by small aldosterone-producing adenoma (APA) or idiopathic hyperaldosteronism (IHA) have not been properly diagnosed. To make a more accurate diagnosis in such cases, we developed a new diagnostic procedure for localization of PA, namely, adrenal venous sampling under continuous infusion of adrenocorticotropic hormone (ACTH) and administration of angiotensin II receptor blocker (AVS with ACTH and ARB). Here, we confirm the efficacy of this procedure in the case of a 37-year-old male suspected of having PA. The anticipated diagnosis of PA was based on the presence of hypokalemia, low plasma renin activity (PRA), elevated plasma aldosterone concentration (PAC) and left adrenal mass. However, AVS with ACTH and ARB revealed the presence of bilateral multiple adrenal microadenomas. In the new AVS method, neither ACTH nor the renin-angiotensin system (RAS) exert any influence on the plasma aldosterone level, and a more accurate aldosterone secretary state and a more accurate assessment of the aldosterone secretion of both adrenal glands can be recognized than by conventional AVS. Use of this new method should enable identification of additional cases of APA among patients diagnosed with essential hypertension.     

The role of biochemical tests and clinical symptoms in differential diagnosis of primary aldosteronism

BACKGROUND: Primary aldosteronism (PA) is a secondary form of hypertension resulting from the autonomous hypersecretion of aldosterone. The recognition of PA has an important impact on clinical management, since the choice of therapy is different - surgical for adenoma and medical for hyperplasia. AIM: To evaluate patients with PA in regard to clinical and biochemical factors differentiating between adenoma of adrenal cortex (APA) and idiopathic adrenal hyperplasia (IHA). METHODS: We retrospectively analysed 62 patients with PA (33 females, 29 males, mean age 49.3+/-12.5 years, range 26-78) diagnosed in the Department of Hypertension between 1990-2001. In 37 patients (mean age 47.4+/-12.1 years, 22 females, 15 males) APA was diagnosed whereas in the remaining 26 patients (mean age 52.2+/-12.6 years, 14 males, 11 females) IHA was detected. Clinical manifestation, biochemical, serum aldosterone (SA), plasma renin activity (PRA) as well as echocardiographic parameters and blood pressure (BP) levels were evaluated. Diagnostic accuracy of computed tomography (CT) and scintigraphy was also assessed. RESULTS: Mean systolic BP was significantly higher in the patients with APA. Both groups had similar mean diastolic BP. Severe hypertension, resistant to three or more medications, was found in 63.3% of all patients. Muscle weakness was reported by 39.7% of patients, polyuria - by 19%, and polydypsia - by 10.3% of patients. Patients with muscle weakness had higher mean systolic BP level and lower plasma potassium level than patients without this complaint. Symptoms suggesting cardiac arrhythmia were reported by 45% of patients. A normal potassium level was found in 25.8% of all patients. The hypokalemic patients were younger, had shorter known duration of hypertension, higher mean systolic BP level and higher SA concentration than the normokalemic patients. Supine SA levels were significantly higher in the APA group than in the IHA group (50.3+/-29.0 ng% vs 30.5+/-14.7 ng%; p<0.001). The SA/PRA ratio higher than 30:1 was found in all patients. Response to postural test with a rise in SA concentration higher than 30% was observed in 40% patients with APA and in 87.5% patients with IHA (p<0.0001). There was a strong correlation between supine and upright SA level, and systolic and diastolic BP level as well as plasma potassium level. Left ventricular hypertrophy was present in 60% of patients. The differentiation between APA and IHA was possible using CT, scintigraphy or both methods in 75%, 89.2% and 100% of patients, respectively. CONCLUSIONS: One quarter of patients with PA were normokalemic. PA should be suspected especially in patients with severe hypertension, resistant to three or more antihypertensive drugs. Changes in SA concentration during the postural tests such as CT and scintigraphy are useful for differentiation between APA and IHA.     

Effects of naloxone on adrenal cortex regulation in patients with primary aldosteronism

Excess production of proopiomelanocortin (POMC)-derived peptides with aldosterone-stimulating activity has been suggested to play a pathogenetic role in idiopathic hyperaldosteronism (IHA). To further investigate this issue, the opiate receptor antagonist naloxone was administered to 14 patients with primary aldosteronism, 6 with an aldosterone-producing adenoma (APA) and 8 with IHA. Clinical and hormonal effects of iv administration of naloxone (10 mg as a bolus) were compared with those obtained in 8 normal subjects. In normals as well as in APA and IHA patients, naloxone caused a significant increase in plasma cortisol, and no change in ACTH, plasma renin activity (PRA) and aldosterone levels. All subjects were retested after 2 mg dexamethasone. ACTH and cortisol were reduced and PRA was unchanged in all groups, without modifications after naloxone. Baseline aldosterone showed no significant changes in all groups. While normal subjects and APA failed to show any aldosterone response to naloxone after dexamethasone, IHA patients demonstrated a significant decrease. beta-endorphin concentrations were in the normal range before and after dexamethasone. In conclusion, naloxone may have a direct action upon adrenal zona fasciculata increasing the cortisol responsiveness to physiological levels of ACTH in either normals or APA and IHA patients. The decrease of aldosterone induced by naloxone in IHA may be due to an intraadrenal opioid control of zona glomerulosa in this disorder.     

原发性醛固酮增多症的分型诊断

目的 探讨用于原发性醛固酮增多症(原醛症)分型诊断检查方法的价值.方法 收集本院近7年来57例临床确诊的原醛症患者[醛固酮瘤22例,特发性醛固酮增多症(特醛症)26例,原发性肾上腺增生9例],检测患者的血电解质、血浆肾素活性及血、尿醛固酮,将结果与19例原发性高血压患者对照.再通过肾上腺CT、体位激发试验及肾上腺静脉采血检查对原醛症患者分型并随访.结果 (1)醛固酮瘤患者血压及血、尿醛固酮较特醛症患者高,血钾及血浆肾素活性则低,而原发性肾上腺增生患者临床及生化改变介于两者之间.肾上腺CT检查在原醛症分型诊断中的符合率为醛固酮瘤86.4%,特醛症73.1%,原发性肾上腺增生22.2%;肾上腺静脉采血检查以两侧醛固酮之比作为判定标准时符合率为86.4%、80.8%和77.8%,以醛固酮与皮质醇之比为判定标准则符合率分别为95.5%、92.3%及100.0%.(2)醛固酮瘤及原发性肾上腺增生患者术后随访血醛固酮均下降,血压恢复正常者分别为22.7%及44.9%,血钾恢复正常者为83.3%及100.0%,而特醛症患者随访中各项测值无明显变化,另有33.3%诊断时血钾正常的患者随访中出现低血钾.结论 原醛症的分型诊断需依靠多种检查手段综合分析,单纯依赖影像学检查或体位激发试验并不可靠,肾上腺静脉采血检查可作为影像学检查的补充,用两侧醛固酮与皮质醇的比值分析较单纯比较两侧醛固酮之比更为可靠;醛固酮瘤及原发性肾上腺增生患者术后临床及生化测值均得以明显改善,而特醛症患者随访中无明显变化.     

Detecting and treating primary aldosteronism: primary aldosteronism.

Primary aldosteronism (PA) is the most common cause of mineralocorticoid hypertension. Different studies, using the plasma aldosterone concentration to plasma renin activity ratio (PAC/PRA) for the screening of patients with hypertension, have shown a marked increase in the detection rate of PA. Idiopathic bilateral adrenal hyperplasia (IHA) and aldosterone-producing adrenal adenoma (APA), are the leading causes of primary aldosteronism. Glucocorticoid-remediable aldosteronism (GRA), also called familial hyperaldosteronism type I, familial hyperaldosteronism type II and carcinomas are rare causes of PA. Patients with hypertension and hypokalemia, those with a family history of hypertension and stroke at an early age, or patients with medication-resistant hypertension should be screened for PA using the PAC/PRA ratio. If a high ratio is found, a sodium loading test or a captopril test is warranted to confirm the diagnosis. Adrenal gland imaging is important in subtype differentiation (APA vs IHA). Adrenal venous sampling should be used when other tests prove inconclusive. Genetic testing has facilitated detection of GRA. Surgery is considered the treatment of choice for patients with APA, while bilateral hyperplasia subtypes are treated medically. Normalization of aldosterone levels or aldosterone receptor blockade are necessary to prevent the morbidity and mortality associated with hypertension, hypokalemia, and cardiovascular damage.     

Adrenal mineralocorticoids causing hypertension

The three major adrenal mineralocorticoid hormones are aldosterone, deoxycorticosterone (DOC) and corticosterone (B). To date, there are four recognized types of primary aldosteronism: (1) aldosterone-producing adenoma (APA), (2) idiopathic hyperaldosteronism (IHA), (3) indeterminate hyperaldosteronism (IndHA) and (4) glucocorticoid-remediable hyperaldosteronism (GRHA). Preoperative distinction between APA and IHA is best achieved by plotting the basal recumbent plasma renin concentration against the level of aldosterone production after administration of deoxycorticosterone acetate (DOCA). Preoperative predictability has been accurate in thirteen cases. Adrenalectomy effects cure or a marked improvement of hypertension in patients with APA, whereas the results are poor in patients with IHA although the number of patients still remains small. Patients with IndHA have all the features of hyperaldosteronism except aldosterone excretion is readily suppressed by the administration of DOCA, and the administration of spironolactone, 200 to 400 mg/day, corrects the hypertension. GRHA is readily correctable by replacement doses of dexamethasone.     

Medical treatment as an alternative to adrenalectomy in patients with aldosterone-producing adenomas

Primary aldosteronism (PA) and, in particular, its two commonest subtypes (i.e. idiopathic hyperaldosteronism (IHA) and aldosterone-producing adenoma (APA)) have been recognized as the most common cause of secondary hypertension. While 'conservative' medical treatment with aldosterone receptor antagonists is the therapeutic approach of choice in controlling blood pressure in patients with PA due to IHA, the more invasive (laparoscopic) adrenalectomy seems to be the most suitable therapy for patients with APA. In this review, we focus on the medical approach for the management of APA in cases where surgical excision of the adrenal is not possible.     

Adrenal steroid responses to ACTH in glucocorticoid-suppressible aldosteronism

To investigate adrenal responses to adrenocorticotrophin (ACTH), we infused graded doses of ACTH (1.25 to 20.0 mIU/30 minutes) in normal subjects, patients with low-renin essential hypertension (LREH), primary aldosteronism (PA), and glucocorticoid-suppressible hyperaldosteronism (GSH). Plasma aldosterone, cortisol, corticosterone, and 18-hydroxycorticosterone were measured. The results revealed a greater increase in the plasma aldosterone and 18-hydroxycorticosterone levels evoked by ACTH in the GSH group than in any other group, which suggested enhanced responsiveness of the aldosterone-producing cells to ACTH and a probable adrenal abnormality.     

Endothelin receptor blockade lowers plasma aldosterone levels via different mechanisms in primary aldosteronism and high-to-normal renin hypertension

BACKGROUND: Endothelin (ET)-1 contributes to raising blood pressure (BP) and inducing cardiovascular disease by vasoconstriction and potent stimulation of aldosterone secretion. In the rat this latter effect occurs via ET(B) receptors; in humans in vitro studies implicated both ET(A) and ET(B) receptors, but there is no conclusive evidence in vivo. METHODS: We recruited 13 consenting hypertensive patients: six with primary aldosteronism (PA) and seven with high-to-normal renin hypertension (HNRH). They were infused with a low dose (200 nmol/min for 5 min followed by 100 nmol/min for 10 min) of the ET(A)-selective antagonist BQ-123 either alone or, on a different day, together with an identical dose of the ET(B)-selective antagonist BQ-788. Plasma aldosterone, cortisol and ACTH concentration and plasma renin activity (PRA) were measured with radioimmunoassay at -15, 0, 30, 60, 120, 240, 360 min, while BP was recorded non-invasively. RESULTS: BQ-123 alone and combined with BQ-788 significantly lowered mean BP in both PA and HNRH patients (by 6-10 mmHg at nadir; P<0.01). In PA patients, a short-lived decrease of aldosterone was elicited by combined BQ-123 and BQ-788 (-14%; P<0.05), but not by BQ-123 alone; cortisol, ACTH, and PRA were unaffected by either treatment. In HNRH patients, BQ-123 both alone and combined with BQ-788 lowered aldosterone (-39 and -28%, respectively) and PRA (-43 and -16%, respectively), while cortisol and ACTH were unaffected. CONCLUSIONS: Endogenous ET-1 contributes to maintaining the high BP values and the aldosterone secretion in both PA and HNRH patients. In the former patients, the aldosterone secretagogue effect of ET-1 is mediated via ET(B) receptors, while in the latter it occurs mainly via ET(A)-mediated stimulation of renin production.     

Primary Aldosteronism: Effects of Inhibition of ACTH and Potassium Administration on Plasma Aldosterone Concentration

The relative roles of ACTH, angiotensin and potassium in influencing aldosterone secretion in primary aldosteronism were assessed by direct or indirect means. In untreated patients with primary aldosteronism caused either by adrenal adenoma or hyperplasia plasma aldosterone and cortisol concentrations fluctuated in unison and dexamethasone reduced both hormones markedly. Only when renin-angiotens in system was greatly activated and plasma potassium normalized by medical treatment was dexamethasone less successful in lowering plasma aldosterone concentration. Potassium infusion of 10, 20 and 30 mEq/hr in patients with adenoma failed to elicit any increase in plasma aldosterone concentration despite significant increases in plasma potassium levels. These results suggest that patients with primary aldosteronism due to adrenal adenoma are relatively more sensitive to small changes in plasma ACTH level than those in plasma angiotensin or potassium levels. In recumbent patients with adrenal hyperplasia ACTH also modulates plasma aldosterone concentration.     

Prospective evaluation of the saline infusion test for excluding primary aldosteronism due to aldosterone-producing adenoma

BACKGROUND: Data on the performance of the tests used to confirm the diagnosis of primary aldosteronism (PA) are limited. OBJECTIVE: To prospectively investigate the accuracy of the saline infusion test (SIT). METHODS: Three hundred and seventeen (26.9%) out of 1125 patients screened in the PAPY study underwent measurement of plasma aldosterone, cortisol and renin activity after infusion of 2 l of isotonic saline intravenously over 4 h. They comprised patients with a baseline aldosterone/renin ratio (ARR) > 40 and one every four patients not fulfilling such criterion. The area under the receiver-operator characteristic curves (AUC) of aldosterone values after SIT was used as a measure of accuracy for diagnosing PA, aldosterone-producing adenoma (APA) or idiopathic hyperaldosteronism (IHA). RESULTS: One hundred and twenty (37.9%) patients had PA that was due to an APA in 46 (38.3%) and to IHA in 74 (61.7%). No untoward effect occurred with the SIT. The AUC (0.811 +/- 0.026, 0.878 +/- 0.040 and 0.784 +/- 0.034 for identification of PA, APA and IHA, respectively) was higher (P < 0.0001) than that under the diagonal. By sensitivity/specificity versus criterion values plot, the best aldosterone cut-off values for identifying APA and IHA were 6.75 and 6.91 ng/dl, respectively. However, even at these optimal cut-offs, sensitivity and specificity were moderate because of values overlapping between patients with and without the disease. Moreover, there were no differences of AUC and aldosterone cut-offs between APA and IHA. CONCLUSION: In a multicenter study the SIT was safe and specific for excluding PA, but had no place for discriminating between an APA and IHA.     

A prospective study of the prevalence of primary aldosteronism in 1,125 hypertensive patients.

OBJECTIVES: We prospectively investigated the prevalence of curable forms of primary aldosteronism (PA) in newly diagnosed hypertensive patients. BACKGROUND: The prevalence of curable forms of PA is currently unknown, although retrospective data suggest that it is not as low as commonly perceived. METHODS: Consecutive hypertensive patients referred to 14 hypertension centers underwent a diagnostic protocol composed of measurement of Na+ and K+ in serum and 24-h urine, sitting plasma renin activity, and aldosterone at baseline and after 50 mg captopril. The patients with an aldosterone/renin ratio >40 at baseline, and/or >30 after captopril, and/or a probability of PA (by a logistic discriminant function) > or =50% underwent imaging tests and adrenal vein sampling (AVS) or adrenocortical scintigraphy to identify the underlying adrenal pathology. An aldosterone-producing adenoma (APA) was diagnosed in patients who in addition to excess autonomous aldosterone secretion showed: 1) lateralized aldosterone secretion at AVS or adrenocortical scintigraphy, 2) adenoma at surgery and pathology, and 3) a blood pressure decrease after adrenalectomy. Evidence of excess autonomous aldosterone secretion without such criteria led to a diagnosis of idiopathic hyperaldosteronism (IHA). RESULTS: A total of 1,180 patients (age 46 +/- 12 years) were enrolled; a conclusive diagnosis was attained in 1,125 (95.3%). Of these, 54 (4.8%) had an APA and 72 (6.4%) had an IHA. There were more APA (62.5%) and fewer IHA cases (37.5%) at centers where AVS was available (p = 0.002); the opposite occurred where AVS was unavailable. CONCLUSIONS: In newly diagnosed hypertensive patients referred to hypertension centers, the prevalence of APA is high (4.8%). The availability of AVS is essential for an accurate identification of the adrenocortical pathologies underlying PA.     

Primary Aldosteronism: Effects of Inhibition of ACTH and Potassium Administration on Plasma Aldosterone Concentration

The relative roles of ACTH, angiotensin and potassium in influencing aldosterone secretion in primary aldosteronism were assessed by direct or indirect means. In untreated patients with primary aldosteronism caused either by adrenal adenoma or hyperplasia plasma aldosterone and cortisol concentrations fluctuated in unison and dexamethasone reduced both hormones markedly. Only when renin-angiotensin system was greatly activated and plasma potassium normalized by medical treatment was dexamethasone less successful in lowering plasma aldosterone concentration. Potassium infusion of 10,20 and 30 mEq/hr in patients with adenoma failed to elicit any increase in plasma aldosterone concentration despite significant increases in plasma potassium levels. These results suggest that patients with primary aldosteronism due to adrenal adenoma are relatively more sensitive to small changes in plasma ACTH level than those in plasma angiotensin or potassium levels. In recumbent patients with adrenal hyperplasia ACTH also modulates plasma aldosterone concentration.     

A rare case of ACTH-independent macronodular adrenal hyperplasia associated with aldosterone-producing adenoma

A 52-year-old man was evaluated for incidentally discovered bilateral adrenal masses. He had drug-resistant hypertension but lacked Cushingoid features. Endocrinological tests revealed autonomous secretion of cortisol and aldosterone with suppressed plasma ACTH and renin activity. A selective adrenal venous sampling demonstrated aldosterone hypersecretion from the left adrenal vein. The clinical diagnosis of subclinical Cushing's syndrome due to ACTH-independent macronodular adrenal hyperplasia (AIMAH) associated with primary aldosteronism was made, and he underwent left adrenalectomy; the resected adrenal lesion was consistent with the pathological diagnosis of AIMAH coexistent with aldosterone-producing adenoma (APA). This is a very rare case of AIMAH with concomitant unilateral APA, whose hypertension improved after surgery.     

Response of plasma ACTH and adrenocortical hormones to potassium loading in essential hypertension

The effect of potassium loading on plasma adrenocortical hormones concentrations in 9 patients with essential hypertension (EH) was investigated. The plasma renin activity (PRA), plasma concentrations of growth hormone (GH), ACTH, cortisol, deoxycorticosterone (DOC), 18-hydroxy-deoxycorticosterone (18-OH-DOC) and aldosterone, and serum electrolytes were measured before and after potassium chloride (KC1) infusion (0.33 mEq/kg/h, for one hour). The KC1 infusion caused significant increases in serum potassium levels and plasma levels of GH, ACTH, cortisol, DOC, 18-OH-DOC and aldosterone, while PRA remained unchanged. Regression analysis at 30 min revealed significant positive correlations between delta ACTH and delta cortisol, between delta ACTH and delta DOC, between delta ACTH and delta 18-OH-DOC. However, the relationship between delta ACTH and delta aldosterone was not statistically significant. These results suggest that (1) acute potassium loading causes a significant increase in the plasma ACTH level and increased levels of adrenocortical hormones may be produced by increased ACTH secretion, and (2) it may be considered that a part of the increased level of plasma aldosterone following acute potassium loading may arise from increased ACTH secretion in EH.     

Plasma beta-endorphin levels in primary aldosteronism

Excessive production of an as yet unidentified aldosterone-stimulating factor may cause idiopathic hyperaldosteronism (IHA). This putative factor may be related to proopiomelanocortin-derived peptides, some of which have aldosterone-stimulating properties. The present study evaluated plasma beta-endorphin, ACTH, cortisol, and aldosterone levels in patients with IHA (n = 10), aldosterone-producing adenomas (n = 4), essential hypertension (n = 11), and normal subjects (n = 10). Plasma and urinary hormone measurements were obtained at timed intervals during an isocaloric, fixed electrolyte intake (Na+, 128 meq/day; K+, 80 meq/day) in a metabolic unit. Plasma for beta-endorphin assay was preincubated with sepharose-bound anti-beta-lipotropin to remove beta-lipotropin that cross-reacted with the beta-endorphin RIA. Mean +/- SE plasma beta-endorphin levels at 0800 h were elevated in IHA patients (47 +/- 13 fmol/ml) compared to those in aldosterone-producing adenoma (25 +/- 9), essential hypertension (16 +/- 1), and normal control (20 +/- 2; P less than 0.05) subjects. Plasma ACTH, plasma cortisol, and urinary cortisol levels were not different in these four groups. These data support the hypothesis that excess production of either beta-endorphin or related proopiomelanocortin-derived peptides may function as aldosterone secretogogue(s) in IHA.