Low Aldosterone Levels Research Articles

ODP442 Posaconazole-induced Pseudohyperaldosteronism (PIPH) in Patient Treated for Acute Myeloid Leukemia

Abstract Case summary A 62-year-old Caucasian female presented to our institute with mechanical fall complicated by cervical spine fracture. She had known history of essential hypertension and recently diagnosed acute myeloid leukemia with myelodysplasia related changes (AML-MRC). She had undergone induction chemotherapy with combination of daunorubicin and cytarabine, resulting in chemotherapy induced prolonged pancytopenia. She was initially started on primary prophylaxis with fluconazole, but was switched to voriconazole due to persistent neutropenia. Patient then developed bilateral upper and lower extremity erythematous popular rash on voriconazole. Decision at that time was to switch to Posaconazole 300 mg orally daily. Three months after initiating Posaconazole, patient presented with severe hypokalemia (2.1 mmol/L) and hypertension. Previously her blood pressure was under control with amlodipine, lisinopril and nadolol. Hypokalemia persisted despite aggressive oral and intermittent intravenous potassium replacement therapy. No sources of potassium loss were identified on clinical history. She had persistently elevated blood pressure (systolic blood pressure of 150-180 mmHg) despite being on her home anti-hypertensive regimen. Further work up showed undetectable plasma aldosterone of less than 1 ng/dL (normal < 28 ng/dL) and plasma renin activity level was suppressed to 0.14 ng/mL/h (normal 0.25–5.82 ng/mL/h) with concurrent potassium of 2.9 mmol/L (normal 3.5-5.3 mmol/l). Diagnosis of pseudohyperaldosteronism was made at this time. Posaconazole gradually stopped and eplerenone 25 mg daily was commenced to selectively block mineralocorticoids receptors to control blood pressure. Subsequently hypokalemia resolved after stopping posaconazole and blood pressure normalized with her original home anti-hypertensive regimen. Eplerenone was eventually stopped. Her potassium level and blood pressure remained normal 2 weeks after discharge. Discussion Recent studies have shown the presentation of hypokalemia and hypertension in nearly a quarter of patients on Posaconazole. The clinical presentation of hypokalemia and hypertension with apparent mineralocorticoid excess was evident in our patient and was consistent with posaconazole-induced pseudohyperaldosteronism (PIPH). Posaconazole interference with the steroid synthesis pathway has been described in various literature. Both cortisol and aldosterone activate aldosterone receptors. In the case of posaconazole, excess mineralocorticoid effect is due to relative selectivity of posaconazole for 11ΒHSD2 inhibition. 11ΒHSD2 inhibition causes increased serum cortisol level by preventing the conversion to inactive cortisone. The high cortisol level cross-reacts with the mineralocorticoid receptor leading to apparent mineralocorticoid excess with low serum aldosterone level and low plasma renin activity. The degree of pseudohyperaldosterone effect on systolic blood pressure and hypokalemia has been strongly associated with serum posaconazole level in some studies. Our patient had resolution of uncontrolled hypertension and hypokalemia after withholding the posaconazole and short term treatment with selective mineralocorticoid receptor blocker. Conclusion Early diagnosis and to allow for early intervention with cessation of the offending agent or treatment with mineralocorticoid antagonists, such as spironolactone and eplerenone is necessary in PIPH. Presentation: No date and time listed

Abstract 121: The Selective Aldosterone Synthase Inhibitor PB6440 Normalizes Blood Pressure In A Human Aldosterone Synthase-Transgenic Mouse Model Of Hypertension

Introduction: Aldosterone synthase inhibitors are emerging as important future treatment options for diseases associated with aldosterone signaling, such as resistant hypertension and chronic renal disease. PB6440 is a potent inhibitor of aldosterone synthase (CYP11B2) with high selectivity over the closely related enzyme CYP11B1. The goal of the current study was to determine whether PB6440 was capable of reducing aldosterone production and blood pressure in an established human aldosterone synthase-transgenic mouse strain (hAS +/- ) that is associated with aldosterone excess and the development of hypertension under a 4% salt diet. Methods: hAS +/- mice were administered PB6440, positive controls and vehicle by oral gavage. In a single-dose study, plasma aldosterone levels were assessed 8 hours after the administration of PB6440 at 2, 10 and 30 mg/kg as well as the positive control fadrozole at 5 mg/kg. In a pilot study, blood pressure was assessed following 10 days of PB6440 once daily at 10 mg/kg as well as the positive control spironolactone at 50 mg/kg. In a definitive study, blood pressure was assessed following 8 weeks of PB6440 once daily at 30 mg/kg as well as spironolactone at 50 mg/kg. Blood pressure was assessed 4-6 hours after drug dosing using a tail-cuff system. Results: In the single-dose study, PB6440 markedly reduced plasma aldosterone with a similar potency to fadrozole (e.g., PB6440 10 mg/kg -96% compared to vehicle; fadrozole 5 mg/kg -96%). In the pilot study, PB6440 normalized both systolic and diastolic blood pressures to that of wild-type mice, with a somewhat greater effect on both parameters than spironolactone at day 10. In the definitive study, PB6440 normalized both systolic and diastolic blood pressures to that of wild-type mice through 8 weeks with an efficacy similar to spironolactone. The decreases in SBP were approximately 30 mm Hg and DBP approximately 20 mm Hg in both drug groups compared to vehicle-treated hAS +/- mice. Conclusions: PB6440 was shown to lower aldosterone levels and normalize blood pressure through 8 weeks in an established mouse model of aldosterone excess and hypertension. PB6440 is a promising potential therapy for the treatment of conditions associated with aldosterone signaling in humans.

A narrative review of Hyporeninemic hypertension-an indicator for monogenic forms of hypertension.

While the role of the renin-angiotensin-aldosterone system (RAAS) in the development of hypertension is well known, the significance and contribution of low renin hypertension is often overlooked. RAAS stimulation results in more tubular absorption of sodium and water along the nephron, contributing to a higher circulating vascular volume. In addition, members of the RAAS system, such as angiotensin II, have direct effects on vascular vasoconstriction, the heart, aldosterone synthesis in the adrenal glands, the sympathetic nervous system, and the central nervous system. This has resulted in a line of antihypertensive therapeutics targeting RAAS with angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), and renin inhibitors, which prevent conversion of angiotensinogen to angiotensin. While general practitioners and nephrologists are well aware of the causes and the long-term consequences of elevated renin and aldosterone levels, the opposite situation with low renin and/or low aldosterone levels is frequently underappreciated. The objective of this review is to provide insight to the less common forms of hyporeninemic hypertension. We searched the PubMed online library for keywords related to hyporeninemic hypertension and focused on the pediatric population. For pathophysiology we focused on literature of the last 5 years. The low renin and aldosterone levels may be indicators of inherited (especially when associated with hypokalemia), monogenic forms of hypertension stimulating excessive tubular sodium and water absorption which subsequently results in plasma volume expansion and hypertension. These forms of hypertension require frequently specific forms of therapy. This underlines the importance of the practitioner to be familiar with these rare diseases. In this review article, we outline the different forms of hypertension characterized by low renin/low aldosterone and low renin/high aldosterone levels, how to diagnose these forms of hypertension, and how to treat them.

Sexual Dimorphic Regulation of MicroRNAs Alters Sodium Transport in the Kidney Distal Nephron

BackgroundHypertension affects more than one billion people worldwide. A key regulator of blood pressure homeostasis is aldosterone, the final signaling hormone of the renin‐angiotensin‐aldosterone‐signaling (RAAS) system. Aldosterone increases sodium (Na+) transport in the kidney distal nephron to regulate blood volume. Premenopausal women are less likely to develop hypertension than age‐matched men, due to both lower aldosterone levels and estrogen signaling. We previously demonstrated that aldosterone alters the expression of microRNAs (miRs) in collecting duct epithelial cells to modulate the Na+ transport response to aldosterone. However, the sex‐specific regulation of miRs and role of estrogen to alter miR expression in the kidney distal nephron has not been explored. This study investigated the hypothesis that estrogen alters aldosterone signaling in the distal nephron by regulating the expression of miRs in collecting duct epithelia.MethodsPrimary cortical collecting duct (CCD) cells derived from male and female mice as well as the mCCD‐cl1 cell line were cultured on permeable filter supports to measure Na+ transport by short‐circuit current recordings in Ussing chambers. Cells were incubated with estrogen for time and dose responses to determine the impact on aldosterone stimulation and Na+ transport. RT‐qPCR quantified miR and mRNA expression and western blot analysis quantified protein expression after aldosterone and estrogen stimulation. In vivo regulation of miRs by aldosterone was confirmed using freshly isolated CCD cells from male and female mice placed on low Na+ diets.ResultsA sex‐specific upregulation of the miR‐17~92 cluster was observed in female mice placed on a low‐Na+ diet to stimulate aldosterone release. MiRs‐19a&b were also upregulated in mCCD cells stimulated with estrogen. Estrogen pretreatment blunted aldosterone stimulation, by targeting the serum and glucocorticoid induced kinase (SGK1) mRNA. Luciferase assays demonstrated that miRs‐19a&b bind to the 3’‐UTR of SGK1. Overexpression of miR‐19 in mCCD cells using miR mimics significantly inhibited aldosterone stimulation of Na+ transport. Conversely, aldosterone stimulation was greater in mCCD cells transfected with a miR‐19 inhibitor (antagomir).ConclusionThe miR‐17~92 cluster is regulated by aldosterone and estrogen. Mir‐19 targets SGK1 and may account for estrogen’s inhibition of aldosterone signaling. This miR cluster may be responsible, in part, for the observed sex‐specific differences in aldosterone signaling. Ongoing studies aim to determine if altering the expression of miR‐17~92 disrupts RAAS signaling in the kidney in vivo.

Pattern Recognition versus Pathogenesis: Electrolytes in a Patient with Adrenal Insufficiency.

Pattern Recognition versus Pathogenesis: Electrolytes in a Patient with Adrenal Insufficiency.

Evaluation of Patients Performed with Saline Infusion Test with a Pre-Diagnosis of Primary Hyperaldosteronism

Background: Primary hyperaldosteronism (PHA) is a primarily treatable cause of arterial hypertension characterized by low plasma renin and high aldosterone levels. The prevalence of secondary hypertension as a common endocrine cause is 5-13%. The plasma aldosterone/renin ratio (ARR) is the best available method for PHA screening. One or more confirmatory tests may be required to confirm or exclude patients' diagnoses. One frequently used confirmatory test is the saline infusion test (SİT). We aimed to screen the patients who underwent SİT with the preliminary diagnosis of PHA and to compare the results of the patients diagnosed with essential hypertension (EH) and PHA.
 Material and Methods: Seventy-seven patients with a history of drug-resistant hypertension or unexplained spontaneous or diuretic-induced hypokalemia or adrenal incidentaloma, or a family history of early-onset hypertension or cerebrovascular accident at a young age (0.05). Basal plasma aldosterone (p

Salt Sensitivity of Blood Pressure and Aldosterone: Interaction Between the Lysine-specific Demethylase 1 Gene, Sex, and Age.

Salt sensitivity of blood pressure (SSBP) is associated with increased cardiovascular risk, especially in individuals of African descent, although the underlying mechanisms remain obscure. Lysine-specific demethylase 1 (LSD1) is a salt-sensitive epigenetic regulator associated with SSBP and aldosterone dysfunction. An LSD1 risk allele in humans is associated with SSBP and lower aldosterone levels in hypertensive individuals of African but not European descent. Heterozygous knockout LSD1 mice display SSBP and aldosterone dysregulation, but this effect is modified by age and biological sex. This might explain differences in cardiovascular risk with aging and biological sex in humans. This work aims to determine if LSD1 risk allele (rs587618) carriers of African descent display a sex-by-age interaction with SSBP and aldosterone regulation. We analyzed 297 individuals of African and European descent from the HyperPATH cohort. We performed multiple regression analyses for outcome variables related to SSBP and aldosterone. LSD1 risk allele carriers of African (but not European) descent had greater SSBP than nonrisk homozygotes. Female LSD1 risk allele carriers of African descent had greater SSBP, mainly relationship-driven by women with low estrogen (postmenopausal). There was a statistically significant LSD1 genotype-sex interaction in aldosterone response to angiotensin II stimulation in individuals aged 50 years or younger, with female carriers displaying decreased aldosterone responsiveness. SSBP associated with LSD1 risk allele status is driven by women with a depleted estrogen state. Mechanisms related to a resistance to develop SSBP in females are uncertain but may relate to an estrogen-modulating effect on mineralocorticoid receptor (MR) activation and/or LSD1 epigenetic regulation of the MR.

A low aldosterone/renin ratio and high soluble ACE2 associate with COVID-19 severity.

Background:The severity of COVID-19 after SARS-CoV-2 infection is unpredictable. Angiotensin-converting enzyme-2 (ACE2) is the receptor responsible for coronavirus binding, while subsequent cell entry relies on priming by the serine protease TMPRSS2 (transmembrane protease, serine 2). Although renin-angiotensin-aldosterone-system (RAAS) blockers have been suggested to upregulate ACE2, their use in COVID-19 patients is now considered well tolerated. The aim of our study was to investigate parameters that determine COVID-19 severity, focusing on RAAS-components and variation in the genes encoding for ACE2 and TMPRSS2.Methods:Adult patients hospitalized due to SARS-CoV-2 infection between May 2020 and October 2020 in the Haga Teaching Hospital were included, and soluble ACE2 (sACE2), renin, aldosterone (in heparin plasma) and polymorphisms in the ACE2 and TMPRSS2 genes (in DNA obtained from EDTA blood) were determined.Measurements and main results:Out of the 188 patients who were included, 60 were defined as severe COVID-19 (ICU and/or death). These patients more often used antidiabetic drugs, were older, had higher renin and sACE2 levels, lower aldosterone levels and a lower aldosterone/renin ratio. In addition, they displayed the TMPRSS2-rs2070788 AA genotype less frequently. No ACE2 polymorphism-related differences were observed. Multivariate regression analysis revealed independent significance for age, sACE2, the aldosterone/renin ratio, and the TMPRSS2 rs2070788 non-AA genotype as predictors of COVID-19 severity, together yielding a C-index of 0.79. Findings were independent of the use of RAAS blockers.Conclusion:High sACE2, a low aldosterone/renin ratio and having the TMPRSS2 rs2070788 non-AA genotype are novel independent determinants that may help to predict COVID-19 disease severity.Trial registration:retrospectively registered.

Aldosterone and renin concentrations were abnormally elevated in a cohort of normotensive pregnant women.

During pregnancy, the renin-angiotensin-aldosterone system (RAAS) undergoes major changes to preserve normal blood pressure (BP) and placental blood flow and to ensure a good pregnancy outcome. Abnormal aldosterone-renin metabolism is a risk factor for arterial hypertension and cardiovascular risk, but its association with pathological conditions in pregnancy remains unknown. Moreover, potential biomarkers associated with these pathological conditions should be identified. To study a cohort of normotensive pregnant women according to their serum aldosterone and plasma renin levels and assay their small extracellular vesicles (sEVs) and a specific protein cargo (LCN2, AT1R). A cohort of 54 normotensive pregnant women at term gestation was included. We determined the BP, serum aldosterone, and plasma renin concentrations. In a subgroup, we isolated their plasma sEVs and semiquantitated two EV proteins (AT1R and LCN2). We set a normal range of aldosterone and renin based on the interquartile range. We identified 5/54 (9%) pregnant women with elevated aldosterone and low renin levels and 5/54 (9%) other pregnant women with low aldosterone and elevated renin levels. No differences were found in sEV-LCN2 or sEV-AT1R. We found that 18% of normotensive pregnant women had either high aldosterone or high renin levels, suggesting a subclinical status similar to primary aldosteronism or hyperreninemia, respectively. Both could evolve to pathological conditions by affecting the maternal vascular and renal physiology and further the BP. sEVs and their specific cargo should be further studied to clarify their role as potential biomarkers of RAAS alterations in pregnant women.

HEPARIN-INDUCED RENAL TUBULAR ACIDOSIS MASQUERADING AS HYPERKALEMIA IN A PATIENT WITH SARS-COV-2

TOPIC: Critical Care TYPE: Medical Student/Resident Case Reports INTRODUCTION: Renal tubular acidosis (RTA) is defined as inadequate excretion of acids via the kidneys to maintain the acid-base balance. In RTA type 4, there is either deficiency or resistance to aldosterone leading to impaired regulation of electrolytes and hydrogen ions. This leads to hyponatremia, hyperkalemia, and acidemia. We present an unsuspecting etiology to RTA type 4 in a critically ill. SARS-CoV-2 patient as noted by heparin use for VTE prophylaxis. [1,2] CASE PRESENTATION: A 72-year-old male with history of chronic kidney disease, leukemia in remission presents with 6-day history of flu-like symptoms including intermittent diarrhea, fevers, decreased appetite, shortness of breath and generalized malaise with exposure to several known sick contacts with SARS-CoV-2. The patient was admitted to the ICU for acute hypoxic respiratory failure and started on Decadron, Remdesivir, Azithromycin, Ceftriaxone, Lovenox, Zinc, and vitamin C and subsequently intubated on day 10. Creatinine up trended and peaked at 3.51 mg/dL on hospital day 14. He developed hyperkalemia initially presumed to be secondary to acute kidney injury. His platelet counts declined by >50%, >10 days after hospitalization. Due to concern for HIT, argatroban was started but stopped due to bleeding. As fondaparinux is contraindicated in renal failure, he was restarted on heparin when HIT ab (-) result was obtained. Serum potassium peaked at 6.7 mmol/L on day 21. He was treated with calcium gluconate, insulin D50, Patiromer 8.4 g with no significant improvement in potassium levels. Due to concerns that use of heparin may be causing hyperkalemia by suppressing aldosterone, heparin was discontinued. Subsequently, serum potassium levels improved to normal range. DISCUSSION: In RTA type 4, either low levels of aldosterone or from kidneys not responding to aldosterone, impaired sodium reabsorption and potassium secretion occurs.[2]. Persistent hyperkalemia in whom there is no apparent cause such as potassium supplements or a potassium-sparing diuretic or renal failure, hypoaldosteronism must be considered [3-5].In COVID-19, there exists a higher propensity for thromboembolic disease and often prevention with heparin can serve as the best treatment. Heparin has a direct toxic impact on the adrenal zona glomerulosa cells, which may be facilitated by a drop in the number and affinity of adrenal angiotensin II receptors [4,6]. This reduction in aldosterone can lead to severe hyperkalemia [6]. CONCLUSIONS: This case is unique because hyperkalemia was noted to be refractory to the typical standard treatment given the etiology was hypoaldosteronism likely secondary to heparin use. Most patients with RTA if treated adequately in the early stages do not develop permanent kidney failure, have better mortality and morbidity outcomes and necessitate a broad etiologic differential. REFERENCE #1: Rodriguez Soriano J. Renal tubular acidosis: the clinical entity. J Am Soc Nephrol 2002;13:2160. REFERENCE #2: Renal Tubular Acidosis. www.kidney.niddk.nih.gov.U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES. National Institutes of Health, NIH Publication No. 09–4696, October 2008. REFERENCE #3: DeFronzo RA. Hyperkalemia and hyporeninemic hypoaldosteronism. Kidney Int 1980;17:118. DISCLOSURES: No relevant relationships by Vidya Baleguli, source=Web Response No relevant relationships by Martin Herrera, source=Web Response No relevant relationships by Riaz Mahmood, source=Web Response No relevant relationships by Erine Raybon-Rojas, source=Web Response

A novel nonsense mutation in the β-subunit of the epithelial sodium channel causing Liddle syndrome

Purpose Liddle syndrome is a hereditary form of arterial hypertension caused by mutations in the genes coding of the epithelial sodium channel – SCNN1A, SCNN1B and SCNN1G. It is characterised by early onset of hypertension and variable biochemical features such as hypokalaemia and low plasma concentrations of renin and aldosterone. Phenotypic variability is large and, therefore, LS is probably underdiagnosed. Our objective was to examine a family suspected from Liddle syndrome including genetic testing and evaluate clinical and biochemical features of affected family members. Materials and methods Thirteen probands from the Czech family, related by blood, underwent physical examination, laboratory tests, and genetic testing. Alleles of SCNN1B and SCNN1G genes were examined by PCR amplification and Sanger sequencing of amplicons. Results We identified a novel mutation in the β-subunit of an epithelial sodium channel coded by the SCNN1B gene, causing the nonsense mutation in the protein sequence p.Tyr604*. This mutation was detected in 7 members of the family. The mutation carriers differed in the severity of hypertension and hypokalaemia which appeared only after diuretics in most of them; low aldosterone level (< 0.12 nmol/l) was, however, present in all. Conclusions This finding expands the spectrum of known mutations causing Liddle syndrome. Hypoaldosteronemia was 100% sensitive sign in the mutation carriers. Low levels are observed especially in the Caucasian population reaching 96% sensitivity. Assessment of plasma aldosterone concentration is helpful for differential diagnosis of arterial hypertension. CONDENSED ABSTRACT Liddle syndrome is a hereditary form of arterial hypertension caused by mutations in the genes encoding the epithelial sodium channel’s α-, β- and γ-subunit. It is usually manifested by early onset of hypertension accompanied by low potassium and aldosterone levels. We performed a physical examination, laboratory tests and genetic screening in 13 members of a Czech family. We found a new mutation of the SCNN1B gene which encodes the β-subunit of the epithelial sodium channel. We describe the variability of each family member phenotype and point out the relevance of using aldosterone levels as a high sensitivity marker of Liddle syndrome in Caucasians.

Liddle Syndrome in a Six-Year-Old Girl: A Case Report

Liddle syndrome is a cause of hypertension among children due to mutation in the epithelial sodium channels (ENaC) located in the kidneys. It typically presents with hypertension, hypokalemia, metabolic alkalosis with low renin and aldosterone levels. Although, most cases are children, but adults also present with this disorder owing to late diagnosis. Amiloride and triamterene efficiently improve the condition. Here we present the case of a 6-year-old girl admitted with history of hypertension, diarrhea, vomiting, weakness and palpitations on and off for the last four years. Laboratory investigations revealed metabolic alkalosis, decreased renin and aldosterone levels, hypokalemia and an inverted T wave, U wave and prolonged QT interval on ECG. Any pediatric case presenting with hypertension and electrolyte imbalance should promptly raise suspicion of Liddle syndrome. Timely diagnosis and management play a key role in reducing morbidity and mortality.

Associations of trauma and posttraumatic stress disorder with aldosterone in women

BackgroundPosttraumatic stress disorder (PTSD) has been associated with increased cardiovascular risk, however, underlying mechanisms have not been fully specified. PTSD is associated with stress-related hormones, including dysregulated glucocorticoid activity. Dysregulation of aldosterone, a mineralocorticoid activated by psychological stress and implicated in cardiovascular damage, may be a relevant pathway linking PTSD and cardiovascular risk. Few studies to date have evaluated the association between PTSD and aldosterone, none with repeated measures of aldosterone. We examined if trauma and PTSD were associated with altered aldosterone levels relative to women unexposed to trauma. MethodsThe association of trauma exposure and chronic PTSD with plasma aldosterone levels was investigated in 521 middle-aged women in the Nurses’ Health Study II. Aldosterone was assessed at two time points, 10–16 years apart, and trauma exposure and PTSD were also ascertained for both time points. Regarding exposure assessment, women were characterized based on a structured diagnostic interview as: having chronic PTSD (PTSD at both time points; n = 174); being trauma-exposed (trauma exposure at first time point but no PTSD; n = 174); and being unexposed (no trauma exposure at either time point; reference group for all analyses; n = 173). Linear mixed models examined associations of trauma and PTSD status with log-transformed aldosterone levels, adjusting for covariates and health-related variables that may confound or lie on the pathway between PTSD and altered aldosterone levels. ResultsAcross the sample, mean aldosterone concentration decreased over time. Adjusting for covariates, women with chronic PTSD had significantly lower aldosterone levels averaged over time, compared to women unexposed to trauma (β = − 0.08, p = 0.04). Interactions between trauma/PTSD group and time were not significant, indicating change in aldosterone over time did not differ by trauma/PTSD status. Post-hoc exploratory analyses suggested that menopausal status partially mediated the relationship between chronic PTSD status and aldosterone level, such that postmenopausal status explained 7% of the effect of PTSD on aldosterone. ConclusionsThese findings indicate that PTSD is associated with lower levels of aldosterone. Further work is needed to understand implications of this type of dysregulation in a key biological stress system for cardiovascular and other health outcomes previously linked with PTSD.

Calcineurin-NFATc4 Pathway Is Activated Upon K+-stimulation of Adrenal Aldosterone Production

The mineralocorticoid aldosterone secreted by the adrenal zona glomerulosa (ZG) cells promote renal K+ secretion and Na+ reabsorption; thereby it is critical for the control of ion homeostasis and blood pressure. While the Ca2+/calmodulin-dependent protein kinase (CAMK) pathway regulating K+ stimulated aldosterone production is well studied, little is known about the potentially involved phosphatases. Interestingly, immunosuppression therapy of transplanted patients with protein phosphatase 3 (calcineurin) inhibitors often results in rather low plasma aldosterone levels despite a concomitant hyperkalemia and hyperreninemia. Calcineurin (Cn) is a calcium and calmodulin-dependent protein phosphatase expressed in the adrenal cortex. We tested the hypothesis that Cn participates in the signal transduction pathway mediating the K+-dependent stimulation of aldosterone production. To address this question, we used the adrenocortical cell model NCI-H295R, mouse and human ex vivo adrenal preparations and a ZG-specific and inducible Cn knockout mouse model (ZG-CnB1-KO). Inhibition of Cn with tacrolimus abolished the K+-stimulated expression of CYP11B2 in NCI-H295R cell line as well as mouse and human adrenal pieces, ex vivo. Using a phosphoproteomics analysis, we identified nuclear factor of activated T-cells, cytoplasmic 4 (NFATc4) as a critical downstream factor mediating Cn function. In support of this result, genetic deletion of NFATc4 reduced the basal expression of CYP11B2 and impaired the K+-stimulated expression of this gene. Conversely, the expression of a constitutively active form of NFATc4 drastically increased the expression of CYP11B2 in NCI-H295R cells which remained unaltered upon treatment with K+ or tacrolimus. Finally, preliminary experiments using ZG-CnB1-KO mice suggest that Cn deletion in the ZG blunts the increase in aldosterone excretion triggered by high K+ diet. Altogether, our data indicate that Cn function is indispensable for the physiological regulation of aldosterone production. Moreover, Cn may represent a novel molecular target for the pharmacological treatment of primary aldosteronism.

A Rare Case of Pseudohypoaldosteronism Type II or Gordon Syndrome

Introduction: Pseudohypoaldosteronism type II (PHA II) or Gordon Syndrome is a rare, autosomally inherited disease with unknown prevalence. It is caused by mutations in the WNK1, WNK4, CUL3, or KLHL3 gene. It is characterized by hypertension, hyperkalemia, hyperchloremic metabolic acidosis and low plasma aldosterone levels, but otherwise normal kidney function. The age of onset of PHA2 is variable, ranging from infancy or childhood to adolescence and adultdood. The electrolyte and blood pressure abnormalities of PHA II is often managed with salt restriction and hydrochlorthiazide (HCTZ). Here we report a rare case of Pseudohypoaldosteronism type II in an adolescent patient.Case Presentation: A 16-yo female with past medical history of asthma and anemia presented to the emergency department with acute severe abdominal/suprapubic pain, associated with diaphoresis, non bloody diarrhea and non bilious non bloody vomiting. The patient also reported daily headaches relieved with Tylenol. In the ED, she was found to be hypertensive at 190/118 mmHg. Blood count showed mild anemia but normal white count and platelets. Comprehensive metabolic panel showed sodium 140, potassium 6.6, chloride 115, bicarbonate 16, creatinine 0.5, and normal liver enzymes. Urine electrolytes were as follows: sodium 189, potassium 20.8 and chloride 140. Arterial Blood Gas ahowed pH of 7.32. Plasma renin activity was low normal at 0.34 and aldosterone level was 2. CT scan of abdomen and pelvis was unremarkable. The blood work was consistent with pseudohypoaldosteronism type II or Gordon syndrome. The patient was adopted so there was no family history. She was started on hydrochlorothiazide. Later, she developed severe itching reaction with hydrochlorthiazide. She is currently being treated with Indapamide, with well controlled blood pressure and normal electrolytes.Conclusion: Pseudohypoaldosteronism type II or Gordon’s Syndrome is a rare disease, with usually autosomal dominant inheritance, with no specific diagnostic criteria for diagnosis. It should be suspected in adolescent or adult patients with hyperkalemia with normal glomerular filtartion, accompanied by hypertension (can be absent), metabolic acidosis, hyperchloremia, decreased plasma renin, relatively suppressed aldosteronism and family history of similar findings.

Acute Kidney Injury in a Previously Healthy 15-Year-Old Patient: A Subtle Presentation of Addison’s Disease

Introduction: Primary adrenal insufficiency (PAI), also known as Addison’s disease, is a disorder of the adrenal glands characterized by decreased levels of glucocorticoids and mineralocorticoids. It is a rare condition with a prevalence of 120 cases per million and is less frequently seen in the pediatric population. Here, we report a previously healthy 15-year-old patient with acute kidney injury (AKI) and PAI. Case Presentation: The patient was admitted to the hospital after findings of abnormal laboratory studies, which included an elevated BUN (53 mg/dL), creatinine (1.39 mg/dL), calcium (11.3 mg/dL), potassium (5.6 mmol/L), and hyponatremia (126 mmol/L). These were performed at an outpatient visit due to three-week history of back pain, fatigue and emesis. On admission, he had stable vital signs. Physical examination revealed generalized darkening of skin, more noticeable on the knuckles and palmar creases, with hyperpigmented patches in oral mucosa and both upper extremities. Although his renal function, serum potassium and calcium levels normalized after intravenous hydration with normal saline, hyponatremia (128 mmol/L) continued. His urine analysis and renal ultrasound were normal. Due to his hyperpigmentation and persistent hyponatremia, PAI was suspected. An ACTH stimulation test revealed that basal and stimulated serum cortisol levels were low, 2.6 mcg/dL and 2.9 mcg/dL, respectively. His plasma ACTH level was elevated at 1,625 pg/mL and serum aldosterone level was low at <4.0 ng/dL. These results were consistent with PAI. The patient’s hyponatremia resolved after receiving stress dose hydrocortisone. He was discharged home on hydrocortisone and fludrocortisone with endocrinology follow up. Discussion: PAI is well described in the literature, though reports in pediatrics vary. Patients may present with nonspecific symptoms such as unexplained weight loss, fatigue, diffuse abdominal pain, nausea, vomiting and muscular weakness. These symptoms may be of insidious onset, which often leads to delayed diagnosis. Physical signs include hypotension and hyperpigmentation. Characteristic biochemical findings are hyponatremia, hyperkalemia and hypoglycemia. Despite the electrolyte derangements, AKI is not a common presentation of PAI. There are only a few case reports associating these two diseases. In this case, his symptoms and abnormal electrolytes were initially considered to be the result of AKI of unknown origin. PAI only became a suspicion after a careful physical exam and persistent hyponatremia despite improvement of his AKI with fluid resuscitation. His low serum cortisol and aldosterone levels with elevated plasma ACTH confirmed the diagnosis of PAI. Conclusion: This case highlights a unique presentation of PAI in an adolescent. A timely diagnosis reduces the risk of unwanted and potentially life-threatening complications such as an Addisonian crisis.

RNA-Binding Protein Musashi-2 Inhibits Aldosterone Production

The adrenal cortex is the site of steroid hormone synthesis. These hormones control important physiological processes like metabolism, blood pressure and volume, and sexual characteristic development. While the signaling pathways, transcription factors, and steroidogenic enzymes are well-characterized, surprisingly little is known about the contribution RNA-binding proteins (RBPs). RBPs exert post-transcriptional control by interacting with specific elements within target mRNAs. Here we focus on the RBP, Mushashi-2 (MSI2), which binds to UAG sequences in the 3’UTR of its target transcripts. MSI2 is required for development of steroidogenic tissues which is consistent with its higher mRNA levels in human ovaries and testis. MSI2 also exhibits high expression levels in human adrenal tissue and the immortalized human adrenocortical cell line (H295R). Based on the compelling MSI2 expression pattern, we set out to determine the role of MSI2 on aldosterone production. Depletion of MSI2 using siRNA led to significantly lower aldosterone levels in H295R cells stimulated with AngII. We also employed an orthogonal loss-of-function approach by co-treating cells with AngII and increasing concentrations of Ro-08-2750 (Ro), a direct and selective inhibitor of MSI2-RNA interactions. Ro inhibited aldosterone production in a dose-dependent manner at 1 µM with almost complete inhibition at 5 µM. The molecular mechanism by which MSI2 regulates target RNA translation and/or decay is unknown. Moreover, whether MSI2 acts as a repressor or activator appears to be context dependent. Our goal is to determine the precise molecular mechanism by which MSI2 promotes aldosterone production. Specifically, we will identify MSI2 targets, temporally resolved consequences of MSI2 inhibition, and protein interaction partners. This work will impact our understanding of fundamental principles of RBP-mediated regulation, as well as novel regulatory mechanisms underlying human steroid hormone synthesis. Indeed, Ro (or further optimized compounds) may represent new therapeutic avenues for adrenal disease.

Aldosterone Insufficiency Contributes to Calcineurin Inhibitor‐induced Hyperkalemia

The mineralocorticoid aldosterone promotes renal K+ excretion and Na+ reabsorption; thereby it is critical for the regulation of ion homeostasis and blood pressure. Interestingly, immunosuppression therapy with protein phosphatase 3 (calcineurin) inhibitors often results in rather low plasma aldosterone levels despite a concomitant hyperkalemia and hyperreninemia. Calcineurin (Cn) is a calcium and calmodulin-dependent protein phosphatase expressed in the adrenal cortex. We tested the hypothesis that Cn participates in the signal transduction pathway mediating the K+-dependent stimulation of aldosterone production. To address this question, we used the adrenocortical cell model NCI-H295R, mouse and human ex vivo adrenal preparations and a ZG-specific and inducible Cn-beta subunit 1 (CnB1) knockout mouse model (ZG-CnB1-KO). Inhibition of Cn with tacrolimus abolished the K+-stimulated expression of CYP11B2 in NCI-H295R cell line as well as in mouse and human adrenal pieces, ex vivo. Moreover, high K+ diet-dependent increase in aldosterone production was blunted in wild type mice treated with tacrolimus. Furthermore, male ZG-CnB1-KO mice fed a high K+ diet exhibited a decreased aldosterone excretion compared to control animals while ZG-CnB1-KO females became hyperkalemic. Using a phosphoproteomics analysis, we identified the nuclear factor of activated T-cells, cytoplasmic 4 (NFATc4) as a downstream factor regulated by Cn. The genetic deletion of NFATc4 in NCI-H295R cells reduced the basal expression of CYP11B2 and blunted the K+-stimulated expression of this gene. Conversely, the expression of a constitutively active form of NFATc4 in NCI-H295R cells drastically increased the expression of CYP11B2 which remained unaltered upon treatment with K+ or tacrolimus. Altogether, our data indicate that the calcineurin-NFATc4 pathway is activated by K+ to promote adrenal aldosterone production. Moreover, our data indicate that insufficient aldosterone production contributes to Cn inhibitor-induced hyperkalemia.

LIDDLE SYNDROME – DETECTION OF NOVEL MUTATION IN A FAMILY WITH HYPERTENSION

Abstract Objective: Liddle syndrome is a rare monogenic form of arterial hypertension with autosomal dominant inheritance. It is caused by mutation of genes coding one of three subunits of epithelial sodium channel (ENaC), which is located in distal nephron. Under physiological conditions, its expression and activity is regulated to maintain fluid and electrolytes homeostasis by reabsorbing Na+. Mutated channel cannot be degraded and therefore, it is accumulated on cell membrane; this results in enhanced sodium reabsorption. The most common clinical presentation of Liddle syndrome is early onset of hypertension, hypokalemia, suppressed plasma renin activity and low plasma aldosterone level. Up to now, 36 mutations causing Liddle syndrome were described. Design and method: Genetic assessment was performed in a Czech family of three generations (n = 14, see Figure) where hypertension and tendency to hypokalemia was present in several members. We used PCR amplification of specific alleles of SCNN1B and SCNN1G genes which was followed by Sanger sequencing. Results: We present a novel mutation causing Liddle syndrome: Tyr604∗ in beta-subunit of epithelial sodium channel. This mutation is supposed to generate a premature stop codon at position 604, resulting in truncated beta-subunit of EnaC. It was found in 7 members of the family: I-1, II-1 and 2, and III-1 to 4. Phenotypes of these subjects were different: from severe hypertension and hypokalemia (subjects I-1 and III-3, manifestation in 10 and 5 years, respectively) to normotension with normal potassium levels (III-1 and 2, now aged 8 and 10 years, respectively); however, all the seven subjects with mutation had hypoaldosteronism (serum level &lt; 0.13 ng/ml). Conclusions: A new mutation causing Liddle syndrome is described. It is manifested with different severity and mild forms that are not manifested in early childhood exist; thus, Liddle syndrome may be more frequent among adult hypertensive subjects than currently supposed. Proper diagnosis is important as the patients respond well to treatment with ENaC blocker amiloride.

Hypokalemia-Induced Rhabdomyolysis Caused by Adrenal Tumor-Related Primary Aldosteronism: A Report of 2 Cases

Case seriesPatients: Male, 53-year-old • Male, 46-year-oldFinal Diagnosis: Primary aldosteronismSymptoms: Myalgia • weaknessMedication: —Clinical Procedure: AdrenalectomySpecialty: Endocrinology and Metabolic • UrologyObjective:Unusual clinical courseBackground:Primary aldosteronism, also known as Conn’s syndrome, is a clinical condition caused by excessive production of aldosterone. The classic presenting signs of primary aldosteronism are hypertension and hypokalemia. However, rhabdomyolysis induced by severe hypokalemia is a rare manifestation of primary aldosteronism. There were only a few cases presented in the English literature over the last 4 decades.Case Report:We present 2 cases, a 53-year-old man and a 46-year-old man, with severe hypokalemia-induced rhabdomyolysis caused by adrenal tumor-related primary aldosteronism. Both of these patients were under medical treatment with oral anti-hypertension drug for hypertension, but were poorly controlled. They both presented to the Emergency Department with muscle weakness and pain. Laboratory testing showed elevated creatinine phosphokinase (CPK) and low serum potassium levels. Hypokalemia-induced rhabdomyolysis was suspected. A further endocrine survey showed low PRA (plasma renin activity) and high aldosterone levels, finding which are compatible with primary aldosteronism. Computed tomography (CT) was arranged for further evaluation, and adrenal tumors were found in both cases. Both patients underwent robotic-assisted laparoscopic adrenal-ectomy. In both cases, there was no recurrence of hypokalemia without potassium supplementation, and their hypertension was under better control at further follow-up visits.Conclusions:Hypokalemic rhabdomyolysis is a rare manifestation of primary aldosteronism. It might be difficult to making a diagnosis when rhabdomyolysis and severe hypokalemia are the first manifestations in patients with primary aldosteronism. The use of diuretics for hypertension treatment might be a risk factor for extremely low potassium levels, which can induce rhabdomyolysis in patients with primary aldosteronism.