Arterial hypertension is a major cardiovascular risk factor that affects between 10 and 40% of the population in industrialized countries. Primary aldosteronism (PA) is the most common form of secondary hypertension with an estimated prevalence of around 10% in referral centers and 4% in a primary care setting. Despite its high prevalence until recently, the underlying genetic and molecular basis of this common disease had remained largely obscure. Over the past decade, a number of insights have been achieved that have relied on in vitro cellular systems, wild-type and genetically modified in vivo models, as well as clinical studies in well-characterized patient populations. This progress has been made possible by a number of independent technical developments including that of specific hormone assays that allow measurement in small sample volumes as well as genetic techniques that enable high-throughput sequencing of a large number of samples. Furthermore, animal models have provided important insights into the physiology of aldosterone regulation that have served as a starting point for investigation of mechanisms involved in autonomous aldosterone secretion. Finally, national and international networks that have built up registries and biobanks have been instrumental in fostering translational research endeavors in PA. Therefore, it is to be expected that in the near future, further pathophysiological mechanisms that result in autonomous aldosterone secretion will be unraveled.
Gurpreet Anand and Felix Beuschlein
With the introduction of hormonal substitution therapy in the 1950s, adrenal insufficiency (AI) has been turned into a manageable disease in pregnant women. In fact, in the light of glucocorticoid replacement therapy and improved obstetric care, it is realistic to expect good maternal and fetal outcomes in patients with AI. However, there are still a number of challenges such as establishing the diagnosis of AI in pregnant women and optimizing the treatment of AI and related comorbidities prior to as well as during pregnancy. Clinical and biochemical diagnoses of a new-onset AI may be challenging because of overlapping symptoms of normal pregnancy as well as pregnancy-induced changes in cortisol values. Physiological changes occurring during pregnancy should be taken into account while adjusting the substitution therapy. The high proportion of reported adrenal crisis in pregnant women with AI highlights persistent problems in this particular clinical situation. Due to the rarity of the disease, there is no prospective data-guiding management of pregnancy in patients with known AI. The aim of this review is to summarize the maternal and fetal outcomes based on recently published case reports in patients with AI and to suggest a practical approach to diagnose and manage AI in pregnancy.
Oliver Zwermann, Dominik M Schulte, Martin Reincke and Felix Beuschlein
Objectives: Although several lines of evidence suggest that the overall effects of the ACTH receptor, melanocortin 2 receptor (MC2-R), mediated signal transduction on adrenocortical growth and tumorigenesis are anti-proliferative, activation of MC2-R induces mitogens like jun, fos, and myc and activates the MAPK pathway. In vivo, potential effects of endogenous ACTH on adrenal tumori-genesis can not be separated from effects of other POMC derived peptides.
Methods: Murine adrenocortical tumor cells that lack MC2-R expression (Y6pcDNA) and Y6 cells stablely transfected with MC2-R (Y6MC2-R) were generated. Presence of functional MC2-R was demonstrated by RT-PCR and Western blot using an antibody for phosphorylated CREB. As a syngenic tumor model, LaHeF1/J mice simultaneously received 107 Y6MC2-R and Y6pcDNA subcutaneously, giving rise to MC2-R positive and negative tumors within the same animal. Animals were treated for 3 weeks in groups of 12 according to the following schedule: group A, control animals receiving saline injection; group B, animals receiving 5.7 ng/injection of a slow release formula of ACTH 1-24 administered i.p. three times a week (aiming at a low physiologic dose); and group C, animals receiving 57 ng/injection of ACTH 1-24 (high physiological dose).
Results: Twenty days of ACTH 1-24 treatment did not significantly affect corticosterone levels, endogenous ACTH levels or adrenal and thymus weight compared with saline injection. However, ACTH 1-24 treatment of group B and C mice significantly reduced tumor weight in MC2-R positive tumors in a dose dependent manner (P = 0.03), while no significant difference in tumor mass was observed in MC2-R negative tumors. PCNA and TUNEL staining, together with morphological characterization, demonstrated that these in vivo effects were due to reduced proliferation, while apoptosis and cellular hypertrophy within the tumor remained unchanged.
Conclusion: MC2-R expression is associated with a less aggressive adrenal tumor phenotype and anti-proliferative effects can be amplified through stimulation with physiological doses of ACTH.
Guido Di Dalmazi, Renato Pasquali, Felix Beuschlein and Martin Reincke
Subclinical hypercortisolism (SH), defined as alterations of the hypothalamus–pituitary–adrenal axis in the absence of clinical signs or symptoms related to cortisol secretion, is a common finding in patients with adrenal incidentalomas. The clinical correlates of this pathological condition have become clearer over the last few years. The aim of this review is to summarize the co-morbidities and the clinical outcomes of patients with SH. According to the analysis of the results of the studies published within the last 15 years, hypertension and type 2 diabetes are a common finding in patients with SH, occurring roughly in 2/3 and 1/3 of the patients respectively. Moreover, several additional cardiovascular and metabolic complications, like endothelial damage, increased visceral fat accumulation and impaired lipid metabolism have been shown to increase the cardiovascular risk of those patients. Accordingly, recent independent reports investigating the natural history of the disease in a long-term follow-up setting have shown that patients with SH have a higher incidence of cardiovascular events and related mortality. Moreover, longitudinal studies have also shown increased incidence of osteoporotic vertebral fractures. Future research is needed to improve the diagnostic performance of hormonal tests, by assessment of the complete steroid profile with more accurate assays, and to define the efficacy of surgical vs medical treatment in a randomized-controlled setting.
Nicole Reisch, Marc Slawik, Oliver Zwermann, Felix Beuschlein and Martin Reincke
Objective: Adrenocorticotropic hormone (ACTH) is the primary secretagogue stimulating secretion of adrenal androgens (AA). Yet, genetic and environmental factors are assumed to play a determining role in the regulation of their biosynthesis and thus might explain the high variability of AA levels. Here we investigate the influence of an ACTH receptor promoter polymorphism affecting ACTH receptor gene transcription on ACTH-dependent dehydroepiandrosterone (DHEA) secretion.
Design: We recently reported a polymorphism within the transcription initiation site of the ACTH receptor gene promoter that alters the consensus sequence from CTC to CCC at −2 bp. This results in lower promoter activity in vitro and is associated with impaired cortisol response to ACTH stimulation in vivo. We now studied 14 normal, lean volunteers aged 20–35 years (eight CTC/CTC and six CCC/CCC carriers) in a 6-h ACTH stimulation test.
Methods: After overnight dexamethasone suppression, ACTH1-24 was administered continuously in each subject with hourly increasing doses (120–3840 ng/m2 body surface area/h) within a 6-h period. On a separate day, baseline DHEA samples were collected.
Results: In the 6-h ACTH stimulation test, CTC/CTC carriers showed a significantly higher DHEA response than CCC/CCC carriers (area under the curve: 19 367 ± 2919 vs 11 098 ± 1241 nmol/l per min; P < 0.04, Mann–Whitney U-test). In contrast, baseline DHEA concentrations did not differ between groups.
Conclusion: These data demonstrate that genetic variations within the ACTH receptor promoter result in decreased DHEA secretion. Thus, we might have identified one of the genetic factors responsible for variation in ACTH-dependent DHEA secretion.
Caroline Schirpenbach, Lysann Seiler, Christiane Maser-Gluth, Frank Rüdiger, Christian Nickel, Felix Beuschlein and Martin Reincke
Objective: Primary aldosteronism has recently been recognized as the most frequent cause of secondary hypertension. Since most patients are normokalaemic, differentiation to essential hypertension is challenging. As differentiation by baseline aldosterone/renin ratio may be insufficient, diagnosis should be confirmed by additional tests. However, as most confirmatory tests have been evaluated in hypokalaemic primary aldosteronism only, we reassessed the value of the saline infusion test and 24 h urinary aldosterone metabolites as confirmatory tests for both normo- and hypokalaemic primary aldosteronism under current antihypertensive medication.
Patients and methods: 25 patients with primary aldosteronism (11 hypokalaemic, 14 normokalaemic), 29 patients with essential hypertension and 47 normotensive subjects were studied. The hypertensives received their usual medication with the exception of spironolactone. All subjects underwent a standard saline infusion test (determination of plasma aldosterone before and after 2.0 liters of isotonic saline for 4 hours i.v.) and collected a 24 h urine sample for examination of urinary tetrahydroaldosterone and aldosterone-18-glucuronide.
Results: In hypokalaemic primary aldosteronism the saline infusion test showed a reasonable sensitivity (91%) and specificity (90%). However, the test failed to differentiate sufficiently between essential hypertension and normokalaemic primary aldosteronism (sensitivity 57%, specificity 90%). Similarly, urinary tetrahydroaldosterone had higher sensitivity in hypokalaemic than in normokalaemic primary aldosteronism (sensitivity 64% vs 36%, specificity 100%), whereas for aldosterone-18-glucuronide, no differences in hypo- and normokalaemic primary aldosteronism were found (sensitivity 45% and 43%, specificity 100%).
Conclusions: These data show that the saline infusion test as an established test in classical hypokalaemic primary aldosteronism is not a reliable test in the normokalaemic variant of the disease. Due to its low accuracy, determination of urinary aldosterone metabolites did not prove useful in confirming either normo- or hypokalaemic patients. We conclude from our data that these tests should not be used as confirmatory testing in the normokalaemic variant of primary aldosteronism.
Oliver Zwermann, Felix Beuschlein, Enzo Lalli, Albrecht Klink, Paolo Sassone-Corsi and Martin Reincke
Background: The ACTH receptor (ACTH-R) is a member of the seven transmembrane domain receptor super-family. In non-functional adrenal adenomas and adrenocortical carcinomas, ACTH-R expression is low. However, no inhibitory factor for ACTH-R expression has been defined to date. DAX-1 (dosage-sensitive sex reversal, adrenal hypoplasia congenita, critical region on the X chromosome, gene-1) is a general repressor of steroid production, inhibiting steroidogenic factor-1 (SF-1)-dependent expression of multiple steroidogenic enzymes. The aim of this study was to investigate whether ACTH-R gene transcription is affected by DAX-1 and whether this mechanism is involved in down-regulation of ACTH-R expression in adrenocortical tumors.
Methods: We screened 22 adrenocortical tumors for ACTH-R and DAX-1 mRNA expression by Northern blot. For in vitro analyses we co-transfected mouse Y1 adrenocortical carcinoma cells with the luciferase reporter gene vector pGL3 containing full-length constructs of human (h) or mouse (m) ACTH-R promoter together with a DAX-1 expression plasmid. These experiments were also performed using ACTH-R promoter 5′-deletion constructs and constructs mutated at the SF-1-binding sites.
Results: We found a negative correlation between DAX-1 and ACTH-R mRNA expression (R = −0.47, P < 0.02). Accordingly, in vitro expression of DAX-1 significantly reduced hACTH-R and mACTH-R promoter activity by 89 and 55% respectively. DAX-1 inhibition was also present in the shortest construct of a series of 5′-deletion constructs of the human promoter extending from −64 to +40 bp relative to the transcription start site. Mutation of the SF-1-binding sites within the hACTH-R promoter resulted in reduced or abolished DAX-1 inhibition, arguing for a mechanism that involves SF-1 for DAX-1 inhibition.
Conclusions: These data support the concept that DAX-1 is a major repressor of ACTH-R gene expression in vitro and in vivo.
Davide Calebiro, Guido Di Dalmazi, Kerstin Bathon, Cristina L Ronchi and Felix Beuschlein
The cAMP signaling pathway is one of the major players in the regulation of growth and hormonal secretion in adrenocortical cells. Although its role in the pathogenesis of adrenocortical hyperplasia associated with Cushing's syndrome has been clarified, a clear involvement of the cAMP signaling pathway and of one of its major downstream effectors, the protein kinase A (PKA), in sporadic adrenocortical adenomas remained elusive until recently. During the last year, a report by our group and three additional independent groups showed that somatic mutations of PRKACA, the gene coding for the catalytic subunit α of PKA, are a common genetic alteration in patients with Cushing's syndrome due to adrenal adenomas, occurring in 35–65% of the patients. In vitro studies revealed that those mutations are able to disrupt the association between catalytic and regulatory subunits of PKA, leading to a cAMP-independent activity of the enzyme. Despite somatic PRKACA mutations being a common finding in patients with clinically manifest Cushing's syndrome, the pathogenesis of adrenocortical adenomas associated with subclinical hypercortisolism seems to rely on a different molecular background. In this review, the role of cAMP/PKA signaling in the regulation of adrenocortical cell function and its alterations in cortisol-producing adrenocortical adenomas will be summarized, with particular focus on recent developments.
Nicole Reisch, Marina Willige, Denise Kohn, Hans-Peter Schwarz, Bruno Allolio, Martin Reincke, Marcus Quinkler, Stefanie Hahner and Felix Beuschlein
To study adrenal crisis (AC) in patients with congenital adrenal hyperplasia due to classical 21-hydroxylase deficiency (21-OHD). AC was defined as an acute state of health impairment requiring i.v. glucocorticoid administration and hospital admission.
Design and methods
In a cross-sectional study with detailed retrospective assessment, AC was studied following two approaches: i) questionnaire based: 122 adult 21-OHD patients (50 men, 72 women, median age 35 years, range 18–69 years) completed a disease-specific questionnaire; and ii) patient chart based: charts of 67 21-OHD patients (32 males, 35 females, median age 31 years, range 20–66 years) were analyzed from diagnosis to last follow-up with regard to frequency and causes of AC since diagnosis.
Evaluation of questionnaires revealed 257 ACs in 4456 patient years (py; frequency 5.8 crises/100 py), while patient charts documented 106 ACs in 2181 py (4.9 crises/100 py). The chart-based evaluation showed that gastrointestinal infections (29%) and salt-wasting crisis (18%) were the main causes of AC. In 14%, the cause remained uncertain. There was no difference in the overall frequency of AC in males and females. AC mostly occurred during childhood, with more than 70% of AC in the first 10 years of life and one-third of AC in the first year of life. Still, 20% of cases of AC were observed in adults (>18 years).
Our data demonstrate a significant risk of AC in patients with 21-OHD over lifetime. Specific age-adapted and repeated crisis prevention training may help to reduce morbidity due to AC in 21-OHD.
Matthias J Betz, Christoph Degenhart, Evelyn Fischer, Anna Pallauf, Volker Brand, Ulrich Linsenmaier, Felix Beuschlein, Martin Bidlingmaier and Martin Reincke
Adrenal vein sampling (AVS) is considered the gold standard in the differential diagnosis of primary aldosteronism (PA), but success rates vary between centers. We hypothesized that rapid (intraprocedure) cortisol measurement can improve performance in a center with initially low AVS success rate.
We analyzed 46 patients with confirmed PA studied between 2008 and 2010. Forty-seven PA patients studied between 2004 and 2008 identified by retrospective chart review served as controls. All patients were treated at a single tertiary care university hospital.
Starting in 2008, rapid cortisol assays (RCA) were performed in all patients during the AVS procedure. A cortisol gradient of ≥2.0 between adrenal vein and a femoral vein sample was used as success criterion. Up to two repeat samples were drawn if adrenal vein cortisol was below this threshold.
During the control period 26 of 47 AVS were successful (55%). After introduction of RCA, 39 out of 46 AVS (85%) were successful (P=0.003). In 21 of the 46 cases (46%) a resampling was necessary. The increase in overall success was due to an increase in successful right AVS (85 vs 62% before introduction of RCA; P=0.02) and a training effect (P=0.024 for trend).
RCA during AVS are useful in centers with an initially low AVS success rate.