Assay characteristics influence the aldosterone to renin ratio as a screening tool for primary aldosteronism: results of the German Conn's registry

Primary aldosteronism (PA) is the most frequent cause of secondary arterial hypertension. The aldosterone to renin ratio (ARR) is the gold standard for screening, but variability between biochemical methods used remains of concern. The aim of the study was to analyze center-specific features of biochemical diagnostic strategies prior to the 2008 consensus within the German Conn's Registry. The study was designed as a retrospective study in 5 tertiary care hospitals. Patients analyzed for PA between 1990 and 2006 were studied. Characteristics of the assays used to determine ARR during establishing the diagnosis of PA were analyzed in the retrospective part of the German Conn's Registry. Eighty-six out of 484 documented ARR values had to be excluded from further evaluations because the laboratory or the assays were unknown. In the remaining 398 patients ARR was determined using 10 different assay combinations in the centers (aldosterone plus plasma renin activity or concentration). Considerable differences were seen between the mean concentrations for aldosterone (p<0.0001), renin concentration (p<0.001), and renin activity (p=0.009) for the different assays. The differences between the absolute concentrations measured by the different assays also had significant impact upon the resulting mean ratios. If published cutoff values are applied, the use of different commercial assays to determine the ARR in clinical routine results in major differences in positive screening rates. This heterogeneity affects sensitivity and specificity of screening for PA. Our data emphasize the importance of standardized screening procedures, which must include standardization of biochemical methods.

Modified-release prednisone decreases complaints and fatigue compared to standard prednisolone in patients with adrenal insufficiency

Patients with adrenal insufficiency (AI) receive first glucocorticoid replacement dose after waking, resulting in a 3-5 h delay compared to physiological secretion. Impaired quality of life (QoL) and fatigue might be due to this delayed dose scheme. Modified-release glucocorticoid preparations might have therapeutic advantages. Exploratory pilot study including 14 patients with AI was conducted in a single university center. Patients on morning dose prednisolone (5 mg) were included, switched to modified-release prednisone (5 mg) at 10 PM for 3 months, and then switched back on standard prednisolone. 3 standardized questionnaires (GBB-24, MFI, and AddiQoL) investigating complaints and fatigue were completed at baseline, after 3, and 6 months. Data regarding clinical and hormonal parameters were assessed. Modified-release prednisone showed significant improvement in one of 4 scales of GBB-24 and positive trends to better scores in 3 of 4 scales. The global score of discomfort improved significantly. The MFI showed also significant improvement in 3 of 5 scales and positive trend to better scores in 2 scales. Significant changes to better scores were seen in 4 out of 30 items of the AddiQoL. Modified-release prednisone showed decreased complaints and fatigue compared to standard prednisolone indicating importance of glucocorticoid increase in early morning hours before waking.

[Addison's disease]

The clinical signs and symptoms of primary adrenal insufficiency are unspecific often causing a delayed diagnosis or even misdiagnosis. In the diagnostic work-up the short synacthen test is regarded as the gold standard. Hydrocortisone and fludrocortisone are the preferred therapy for Addison's disease. The management and surveillance of therapy requires experience and several aspects need to be followed to prevent side effects which might occur due to overtreatment or undertreatment. Very important aspects in therapy are the repeated teaching of the patient and relatives, the issuing of an emergency steroid card and the prescription of a glucocorticoid emergency set. Acute adrenal failure (adrenal crisis), which might be the first manifestation of adrenal insufficiency, is a life-threatening situation requiring immediate glucocorticoid administration and fluid substitution. The most common causes for an adrenal crisis are gastrointestinal infections and fever and discontinuation of glucocorticoid therapy. This article gives an up-to-date overview of diagnostic and therapeutic aspects of Addison's disease.

Flutamide increases aldosterone levels in gonadectomized male but not female Wistar rats

BACKGROUND

Sex-specific differences in blood pressure (BP) suggest an important modulating role of testosterone in the kidney. However, little is known about the interaction between androgens and the mineralocorticoid aldosterone. Our objective was to determine the effects of testosterone in gonadectomized male and female rats on a low-salt diet, and to determine the effect of androgen receptor (AR) blockade by flutamide on BP and on aldosterone levels.

METHODS

Normotensive male and female Wistar rats were gonadectomized and put on a low-salt diet. They were treated for 16 days with testosterone or placebo. In addition, the animals received the AR antagonist flutamide or placebo, respectively. BP was measured by tail-cuff method, 24-h urine samples were collected in metabolic cages and blood was collected for hormonal measurements.

RESULTS

Testosterone increased BP in males and females, and this effect could be blocked by flutamide. Flutamide treatment itself significantly increased aldosterone levels in male but not in female rats. These elevated aldosterone levels could be lowered by testosterone treatment during AR blockade. Accordingly to aldosterone levels, flutamide increased in males the serum sodium/potassium to urinary sodium/potassium ratio, an in vivo indicator of renal aldosterone action.

CONCLUSIONS

Testosterone regulates BP in male and female gonadectomized rats via the AR. Flutamide by itself exerts influence over aldosterone in the absence of gonadal steroid replacement suggesting AR involvement in renal sodium handling. These flutamide effects were sex-specific and not seen in female rats.

Sex-specific effects of spironolactone on blood pressure in gonadectomized male and female Wistar rats

A low-salt diet is known to decrease and salt excess to increase blood pressure in humans and rodents. Sex steroids seem to play a role in salt dependent hypertension. However, little is known about sex differences in mineralocorticoid receptor blockade between male and female rats. The objective of the work was at first to investigate the effects of a low-salt vs. a high-salt diet on blood pressure without the influence of gonadal steroids in male and female rats. Second, to determine the sex-specific effects of mineralocorticoid receptor blockade by spironolactone in high-salt and low-salt fed gonadectomized male and female animals. Normotensive male and female Wistar rats were gonadectomized and put on a low (NaCl<0.03%) or high (NaCl=4%) salt diet. On each diet animals received spironolactone or placebo. Blood pressure was measured by tail-cuff-method; 24-h urine samples were collected in metabolic cages and blood was collected for hormonal measurements. High-salt diet significantly increased systolic blood pressure in both sexes. This effect could be blocked effectively by spironolactone only in male rats. Spironolactone treatment significantly increased aldosterone levels in males and females independent of the sodium content of the diet. High sodium diet significantly increased relative kidney weight, which was not altered by spironolactone treatment. Independently of gonadal steroids a high-salt diet increased blood pressure in gonadectomized male and female rats. Spironolactone lowered blood pressure only in male not in female rats on a high-salt diet clearly indicating sex-specific effects of the mineralo-corticoid antagonist spironolactone.

Aldosterone and the kidney

The mineralocorticoid aldosterone is a key regulator of blood pressure, fluid and electrolyte homeostasis, and acts via the mineralocorticoid receptor (MR). In recent years, an increasing number of studies revealed deleterious effects of aldosterone via its receptor. Especially in patients with primary hyperaldosteronism (PHA) a significant higher risk of developing cardiovascular comorbidities and comortalities was reported. Also renal insufficiency is clearly increased in patients with PHA indicating a role of aldosterone and the MR in the pathogenesis of renal injury. It has been shown that aldosterone in combination with an elevated salt intake, leads to renal inflammation, fibrosis, podocyte injury, and mesangial cell proliferation. This review focuses on the current knowledge of aldosterone effects in the kidney and highlights this topic from 2 perspectives: from clinical medicine and from experimental studies.

Bone mineral density is not significantly reduced in adult patients on low-dose glucocorticoid replacement therapy

CONTEXT

Patients with primary adrenal insufficiency (PAI) and patients with congenital adrenal hyperplasia (CAH) receive glucocorticoid replacement therapy, which might cause osteoporosis.

OBJECTIVES

Questions addressed by this study were: 1) Is bone mineral density (BMD) reduced in PAI and CAH on lower glucocorticoid doses than previously reported? 2) Is BMD in PAI influenced by the type of glucocorticoid used? and 3) Does DHEA treatment affect BMD in PAI women?

DESIGN AND PATIENTS

We conducted a prospective, cross-sectional study including 81 PAI patients and 41 CAH patients.

MAIN OUTCOME MEASURES

BMD was measured by dual-energy x-ray absorptiometry. Serum levels of bone turnover markers, minerals, vitamins, hormones, and urinary crosslinks were measured.

RESULTS

PAI and CAH patients received average daily hydrocortisone doses of 12.0 ± 2.7 mg/m(2) (range, 4.9-19.1) and 15.5 ± 7.8 mg/m(2) (range, 5.7-33.7), respectively. BMD varied within the normal reference range (-2 to +2) in both cohorts. However, lower Z-scores for femoral neck and Ward's region were found in CAH compared to PAI women, but not in men. Prednisolone treatment showed significant lower osteocalcin levels and lower Z-scores for lumbar spine and femoral neck compared to PAI patients on hydrocortisone. PAI women treated with DHEA had significantly lower urinary collagen crosslinks and bone alkaline phosphatase, and significantly higher Z-scores in lumbar spine and femoral Ward's region compared to non-DHEA-treated women.

CONCLUSIONS

Adult PAI and CAH patients on low glucocorticoid doses showed normal BMD within the normal reference range. The use of longer acting prednisolone resulted in significantly lower BMD in PAI. In addition, DHEA treatment may have a beneficial effect on bone in Addison's women.

In vivo activity of 11β-hydroxysteroid dehydrogenase type 1 in man: effects of prednisolone and chenodesoxycholic acid

The 11β-hydroxysteroid dehydrogenases (11β-HSDs) play a pivotal role in glucocorticoid (GC) action. 11β-HSD1 is a predominant reductase, activating GCs from inert metabolites, whereas 11β-HSD2 is a potent dehydrogenase inactivating GCs. Knowing the metabolic effects of GCs, a selective inhibition of 11β-HSD1 represents a potential target for therapy of impaired glucose tolerance, insulin insensitivity and central obesity. In vitro, 11β-HSD1 is selectively inhibited by chenodesoxycholic acid (CDCA) and upregulated under GC exposure. Therefore, we aimed to investigate the effects of CDCA and prednisolone on hepatic 11β-HSD1 activity in vivo by measuring 11-reduction of orally given cortisone (E) acetate to cortisol (F). CDCA or placebo was given to 5 male healthy volunteers within a randomised cross-over trial before and after oral administration of 12.5 mg E acetate at 8:00 h. For measurement of in vivo effects of GCs on 11β-HSD1 activity, hepatic reduction of 25 mg E acetate before and after treatment with prednisolone (30 mg for 6 days) was determined in 7 healthy males. Serum GC levels were determined using a fully automated liquid chromatographic system. CDCA had no effect on the activity of 11β-HSD1 in vivo. Prednisolone therapy leads to a marked rise in serum F concentrations and an elevated F/E serum ratio. This proves GC-induced activation of hepatic 11β-HSD1, which could not be extinguished by a parallel increase of IGF-1 under prednisolone. CDCA does not affect in vivo activity of 11β-HSD1 when given in therapeutic dosages. During GC treatment, increased hepatic activation of E to F may aggravate metabolic side effects of GCs such as seen in the metabolic syndrome.

[Primary hyperparathyroidism]

Primary hyperparathyroidism is a common endocrine disease. Since introduction of automated routine measurement of serum calcium the detection of primary hyperparathyroidism has increased significantly. The classical symptoms such as kidney stones, gastrointestinal and bone manifestation are rarely seen nowadays. For this reason, an elevated parathyroid hormone level in a patient with hypercalcemia confirms primary hyperparathyroidism in 95 % of cases. Currently 80 % of these patients are asymptomatic, and therefore criteria for diagnosis and treatment have been discussed on several consensus conferences. After biochemical confirmation has been obtained further diagnostic test aim at locating the tumor should be by ultrasound and 99m TC-sestamibi scintigraphy. The improved diagnostic work-up had led to a better surgical approach with minimally invasive and endoscopic techniques. In addition, quick intraoperative parathyroid hormone measurements confirm immediately the success of surgical treatment. Non-surgical treatment in asymptomatic and elderly patients may be justified. Bisphosphonates are the first choice for medical treatment in patients with bone manifestation and cinacalcet may be given to patients to lower calcium and parathyroid hormone levels.

Comorbidities in primary aldosteronism

Patients presenting with primary aldosteronism experience more cardiovascular events than patients with essential hypertension independent of blood pressure. Therefore, the presence of primary aldosteronism should be detected, not only to determine the cause of hypertension, but also to prevent such complications. This review focuses on human data regarding increased end-organ damage and comorbidities in primary aldosteronism. Special emphasis is put on the effects of aldosterone excess on blood vessels, the heart, the kidney, and the brain. The data reviewed in our article demonstrate that primary aldosteronism is associated with a prevalence of cerebro-, cardiovascular and renal complications that are out of proportion to the blood pressure and benefits substantially from treatment in the long term. In this view, adrenalectomy and aldosterone antagonist treatment seem to be of considerable therapeutic value to control and limit the progression of comorbidities in primary aldosteronism.

Is primary aldosteronism associated with diabetes mellitus? Results of the German Conn's Registry

Aldosterone excess in the context of primary aldosteronism (PA) has been associated with impaired glucose tolerance and diabetes mellitus. We retrospectively assessed the prevalence of diabetes mellitus in patients from the German Conn's Register and compared the data with those from hypertensive subjects of a population-based survey. In a case-control study, we have compared 638 patients with PA from the German Conn's registry who were treated in 6 German centers with 897 hypertensive control subjects from the population-based F3 survey of the Cooperative Health Research in the Region of Augsburg (KORA). The samples were matched for age, sex, and blood pressure in a 1:1 ratio. Risk factors associated with the presence of diabetes mellitus were calculated in 638 patients with PA and 897 hypertensive controls. In the case control study, the diabetes prevalence was calculated in 338 cases and controls. In patients with primary aldosteronism, age, BMI, and a higher number of antihypertensive drugs (lowest tertile vs. highest tertile) were variables associated with diabetes mellitus. In contrast, serum potassium and plasma aldosterone concentrations were not associated with higher diabetes prevalence, whereas diastolic blood pressure was inversely associated with diabetes mellitus. Diabetes mellitus was more prevalent in patients with PA than in 338 matched controls (23 vs. 10% in controls). Our data for the German population show that diabetes mellitus is more prevalent in patients with primary aldosteronism than in hypertensive controls.

Management of steroid replacement in adrenal insufficiency

Adrenal insufficiency is caused by either primary adrenal failure, mostly due to autoimmune adrenalitis, or by hypothalamic-pituitary impairment of the corticotropic axis, predominantly by long-term pharmacodynamic glucocorticoid treatment or by pituitary tumour growth and related treatment. Despite optimized life-saving glucocorticoid and mineralocorticoid replacement therapy, health-related quality of life in adrenal insufficiency is more severely impaired than previously thought and patients with adrenal insufficiency are also threatened by an increased mortality. Optimizing hormone replacement remains one of the most challenging tasks in endocrinology. Monitoring of glucocorticoid replacement quality is hampered by lack of objective assessment tools and therefore largely based on clinical grounds. Thus, long-term management of patients with adrenal insufficiency remains a continuous challenge asking for the experienced specialist. However, diagnosis and management of suspected acute adrenal failure is an important task for all physicians. This review explains the rationale behind the current hormone replacement scheme, points to the deficits and hints at possible future therapies.

Tumor size of Conn's adenoma and comorbidities

Primary aldosteronism (PA) is associated with vascular end organ damage. The aim of the study was to evaluate differences regarding comorbidities depending on tumor size in patients with aldosterone producing adenoma (APA). The retrospective cross-sectional study was done by collection from 6 German centers (German Conn's registry) between 1990 and 2007. Among the 640 registered patients with PA, 60 operated patients with APA were analyzed. The main outcome of measures was the comorbidities depending on tumor size. Thirty-one patients (17 men, 14 women) had an adenoma size <20 mm, and 29 patients (10 men, 19 women) had an adenoma size>/=20 mm. There was no difference in age, preoperative potassium, aldosterone, or creatinine levels, preoperative systolic and diastolic blood pressure, or duration of hypertension between the two groups. In the group with APA <20 mm, cerebrovascular events occurred with a prevalence of 12.9%, cardiac events 16.1%, peripheral vascular events 25.8%, renal insufficiency 16.1%, and sleep apnea 6.4%, respectively. There was no significant difference in comorbidities compared to the group with APA>/=20 mm. Subgroup analysis (n=22) of follow-up data on post-operative systolic and diastolic blood pressure showed no significant difference between these subgroups with regard to potassium, aldosterone or creatinine levels, blood pressure, duration of hypertension, or comorbidities. Our data indicate a high prevalence of comorbidities in patients with APA. However, adenoma size was not correlated with cardio- and cerebrovascular comorbidities, and does not seem to be a prognostic factor for blood pressure outcome.

Sex-specific regulation of ENaC and androgen receptor in female rat kidney

With the beginning of puberty blood pressure increases and is persistently higher in men than in premenopausal women. Sex steroids are known to have complex effects on the renal and cardiovascular system and are involved in blood pressure regulation. The epithelial sodium channel (ENaC) modulates sodium reabsorption in the kidney, but little is known about sex-specific regulation of ENaC subunit expression. Regulation of the androgen receptor (AR) is known to be tissue-specific and age-dependent, but not well studied in the kidney. We investigated the effects of sex steroids on ENaC subunits and renal AR expression in an in vivo rat model. Ovariectomized female Wistar rats were treated with placebo, testosterone, 5 alpha-dihydrotestosterone (DHT) or 17 beta-estradiol (E2) for 14 days, and quantitative PCR and Western immunoblots were performed. DHT significantly decreased expression of all ENaC subunits in female rats, whereas testosterone showed only a trend to lower ENaC expression. These results are in contrast to previous studies where stimulating effects of androgens on the alpha-subunit of ENaC were seen. AR mRNA expression showed a trend to lower levels in females after testosterone treatment in this study. However, estrogen treatment significantly downregulated AR mRNA expression. In male control animals we were able to show a significantly increased expression of AR mRNA upon testosterone treatment. Our data demonstrate that AR and ENaC are regulated by sex steroids. That way sex steroids might modulate renal sodium reabsorption and therefore provide a possible explanation for sex differences in blood pressure.

Cardiovascular and cerebrovascular comorbidities of hypokalemic and normokalemic primary aldosteronism: results of the German Conn's Registry

CONTEXT

Primary aldosteronism (PA) is associated with vascular end-organ damage.

OBJECTIVE

Our objective was to evaluate differences regarding comorbidities between the hypokalemic and normokalemic form of PA.

DESIGN AND SETTING

This was a retrospective cross-sectional study collected from six German centers (German Conn's registry) between 1990 and 2007.

PATIENTS

Of 640 registered patients with PA, 553 patients were analyzed.

MAIN OUTCOME MEASURES

Comorbidities depending on hypokalemia or normokalemia were examined.

RESULTS

Of the 553 patients (61 +/- 13 yr, range 13-96), 56.1% had hypokalemic PA. The systolic (164 +/- 29 vs. 155 +/- 27 mm Hg; P < 0.01) and diastolic (96 +/- 18 vs. 93 +/- 15 mm Hg; P < 0.05) blood pressures were significantly higher in hypokalemic patients than in those with the normokalemic variant. The prevalence of cardiovascular events (angina pectoris, myocardial infarction, chronic cardiac insufficiency, coronary angioplasty) was 16.3%. Atrial fibrillation occurred in 7.1% and other atrial or ventricular arrhythmia in 5.2% of the patients. Angina pectoris and chronic cardiac insufficiency were significantly more prevalent in hypokalemic PA (9.0 vs. 2.1%, P < 0.001; 5.5 vs. 2.1%, P < 0.01). Overall, cerebrovascular comorbidities were not different between hypokalemic and normokalemic patients, however, stroke tended to be more prevalent in normokalemic patients.

CONCLUSIONS

Our data indicate a high prevalence of comorbidities in patients with PA. The hypokalemic variant is defined by a higher morbidity than the normokalemic variant regarding some cardiovascular but not cerebrovascular events. Thus, PA should be sought not only in hypokalemic but also in normokalemic hypertensives because high-excess morbidity occurs in both subgroups.

The serum sodium to urinary sodium to (serum potassium)2 to urinary potassium (SUSPPUP) ratio in patients with primary aldosteronism

BACKGROUND

The aldosterone-to-renin ratio (ARR) is an established diagnostic tool in the screening for primary aldosteronism (PA). However, hormonal determinations are time consuming and expensive. Therefore, we studied the effectiveness of the serum sodium to urinary sodium to (serum potassium)(2) to urinary potassium (SUSPPUP) ratio in the diagnosis of PA.

DESIGN

This study included 35 patients with PA, 71 patients with essential hypertension to whom this diagnosis could be excluded, 23 normal subjects without hypertension, and 22 patients with primary adrenal insufficiency. We compared the SUSPPUP ratios with the ARR in these patient groups.

RESULTS

We show that the ARR distinguished PA from essential hypertension with a sensitivity of 94.2% and a specificity of 92.1% at a cutoff of 33 (ng L(-1): ng L(-1)). It correlated well with the SUSPPUP ratio. The sensitivity and specificity of SUSPPUP was 88.6% and 85.9% at a cutoff of 5.3 (mmol L(-1))(-1), respectively, and thus not as good as the ARR.

CONCLUSIONS

The ARR is a good parameter in the screening for PA. The SUSPPUP ratio is a cheap and rapid tool to assess the extent of mineralocorticoid excess and, therefore, can be offered to more patients. In addition, the application of the SUSPPUP ratio can be extended to patients who suffer from other forms of mineralocorticoid hypertension (e.g. with low aldosterone levels).

Radiofrequency thermal ablation of hepatic metastases of adrenocortical cancer--a case report and review of the literature

AIM

Radiofrequency thermal ablation (RFA) has shown promise as a technique for treating solid tumors. This method has been suggested as an alternative to surgery in patients with adrenocortical carcinoma (ACC).

MATERIALS AND METHODS

We reviewed the literature, and report the case of a patient with stage 4 ACC who received intraoperative and percutaneous RFA of two liver metastasis according to a standard ablation protocol.

RESULTS

Post-interventional imaging in our patient demonstrated that after both interventions, a stellar-like structure of vital tumor tissue had remained within the coagulation necrosis. This was the starting point of a fast and progressive tumor recurrence. We suspect heat-sink effects of blood vessels in the highly vascularized metastasis to cause the tumor recurrence. In literature, there are only a few reports of RFA in ACC patients. In addition, there is no large randomized trial investigating the efficacy of RFA against surgery in those patients.

CONCLUSIONS

Presently, RFA in ACC should be restricted to patients in whom surgery is contraindicated. It is necessary that strongly vascularized ACC metastases deserve a modified ablation protocol due to perfusion related cooling effects and to increase the efficacy of RFA.