Publications by authors named "Michael Stowasser"

Objectives: Aldosterone is over-estimated by direct immunoassay when compared to assay by LC-MS/MS. We have investigated the mechanism for this over-estimation, using dichloromethane (DCM) extraction and a unique matrix of non-synthetic aldosterone-free plasma (ALFP).

Methods: Samples used were from patients with normal estimated Glomerular Filtration Rate (eGFR).

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Background: Primary aldosteronism (PA), a primary adrenal disorder leading to excessive aldosterone production by one or both adrenal glands, is a common cause of hypertension. It is associated with an increased risk of cardiovascular complications compared with primary hypertension. Despite effective methods for diagnosing and treating PA, it remains markedly underdiagnosed and undertreated.

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Background: Primary aldosteronism (PA) is a common treatable cause of hypertension. When caused by unilateral adrenal disease, it is potentially curable by adrenalectomy. However, specialized tests and other factors may delay definitive treatment.

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Hypertension is the most common problem managed in Australian general practice, yet most adults with hypertension do not have their blood pressure (BP) treated to target. Hypertension diagnosis and management rely upon accurate BP measurements performed using a standardised protocol. However, health system barriers prevent doctors from following measurement protocols, leading to inaccurate BP assessments.

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Aim: Using urinary extracellular vesicles (uEVs), we have demonstrated the functional 'renal-K switch' mechanism (the WNK-SPAK-NCC pathway) in both healthy subjects and those with primary aldosteronism. The close relationship between blood pressure and CKD has led to the hypothesis that high potassium intake may be reno-protective through the same mechanism. This study used uEVs to evaluate whether plasma potassium negatively correlates with NCC and its phosphorylation (pNCC) in patients with CKD.

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Background: Primary aldosteronism can be treated medically but there is no standardised method to evaluate treatment outcomes. We aimed to develop criteria for assessing the outcomes of targeted medical treatment of primary aldosteronism, analyse outcomes across an international cohort, and identify factors associated with a complete treatment response.

Methods: An international panel of 31 primary aldosteronism experts used the Delphi method to reach consensus on the definition of complete, partial, or absent biochemical and clinical outcomes of medical treatment of primary aldosteronism.

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Article Synopsis
  • Adrenal vein sampling (AVS) is the preferred method for identifying unilateral subtypes of primary aldosteronism (PA), which can be treated with surgery for a potential cure.
  • The procedure is technically demanding and often performed by specialized interventional radiologists, but variations in protocols can affect its success and patient care.
  • To standardize AVS practices and improve outcomes, an Australian and New Zealand AVS Working Group was formed to create expert consensus recommendations that can be utilized by all healthcare professionals involved in PA management.
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Article Synopsis
  • Primary aldosteronism is linked to increased cardiovascular risks and can affect young adults' arterial health and heart structure before clinical symptoms appear.
  • This study used data from the Raine Study, analyzing young adults at ages 17 and 27 to investigate the relationships between aldosterone levels, arterial stiffness, and left ventricular mass index (LVMI).
  • Results showed that females had higher aldosterone-to-renin ratios than males, and notable associations were found between aldosterone levels and LVMI in males at age 27.
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The mineralocorticoid system, comprising the renin-angiotensin-aldosterone system (RAAS) and associated receptors, is traditionally viewed as a regulator of sodium and fluid balance and blood pressure (BP), with the main mineralocorticoid hormone aldosterone acting via the mineralocorticoid receptor (MR) in distal renal tubules. Over the past few decades, there has been a wider understanding of the role of the mineralocorticoid system in regulating both classical BP-dependent and non-BP-dependent systemic effects. Mounting evidence indicates the novel role of the mineralocorticoid system in cardiometabolic health, with excess mineralocorticoid system activity being associated with adiposity, diabetes, insulin resistance and cardiovascular diseases independent of its effect on BP, and RAAS blockade and MR antagonists offering protection against cardiometabolic dysfunction.

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Low-renin hypertension affects 1 in 4 people with hypertension, but the optimal management of this condition is not known. We hypothesize that a large proportion of people with low-renin hypertension is mediated by excess mineralocorticoid receptor (MR) activation and that targeted treatment with an MR antagonist (MRA) will be beneficial. This randomized, single-blinded, titration-to-effect aims to investigate whether targeted treatment in low-renin hypertension with MRA is better compared to standard antihypertensives in terms of blood pressure control and end-organ protection.

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We describe herein the European Reference Network on Rare Endocrine Conditions clinical practice guideline on diagnosis and management of familial forms of hyperaldosteronism. The guideline panel consisted of 10 experts in primary aldosteronism, endocrine hypertension, paediatric endocrinology, and cardiology as well as a methodologist. A systematic literature search was conducted, and because of the rarity of the condition, most recommendations were based on expert opinion and small patient series.

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Background: Cuff blood pressure (BP) is recommended for guiding hypertension management. However, central BP has been proposed as a superior clinical measurement. This study aimed to determine whether controlling hypertension as measured by central BP was beneficial in reducing left ventricular mass index beyond control of standard cuff hypertension.

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Background: Pregnant patients with obesity may have compromised noninvasive blood pressure (NIBP) measurement. We assessed the accuracy and trending ability of the ClearSight™ finger cuff (FC) with invasive arterial monitoring (INV) and arm NIBP, in obese patients having cesarean delivery.

Methods: Participants were aged ≥18 years, ≥34 weeks gestation, and body mass index (BMI) ≥ 40 kg m.

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Article Synopsis
  • Primary aldosteronism (PA) is a significant but often overlooked cause of hypertension, leading to preventable harm due to slow diagnosis.
  • An international online survey revealed that 35.6% of participants faced diagnostic delays of five years or more, with women and those having multiple health issues experiencing these delays more frequently.
  • After treatment, 74.4% of patients reported fewer symptoms, and 62.3% experienced improved quality of life, highlighting the need for routine PA screening when hypertension is first diagnosed.
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A reninoma is a functional tumor of afferent arteriolar juxtaglomerular cells that secretes the enzyme renin, leading to hyperactivation of the renin-angiotensin-aldosterone system. Reninoma is a potentially curable cause of pathological secondary hyperaldosteronism that results in often severe hypertension and hypokalemia. The lack of suppression of plasma renin contrasts sharply with the much more common primary aldosteronism, but diagnosis is often prompted by screening for that condition.

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Objectives: To evaluate aldosterone and renin levels and aldosterone-to-renin ratios (ARRs) in young Indigenous and non-Indigenous adults in the Northern Territory, and their association with blood pressure levels.

Design: Cross-sectional study; single time point sub-study of two prospective birth cohort studies.

Setting, Participants: Participants in the Aboriginal Birth Cohort (ABC) - born to Indigenous mothers at the Royal Darwin Hospital during 1987-1990 - and the Top End Cohort (TEC) - people born to non-Indigenous mothers in Darwin, recruited during 2007-2009 - aged 32-35 years at the time of this sub-study.

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Background: Primary aldosteronism affects 3-14% of hypertensive patients in the primary care setting and up to 30% in the hypertensive referral units. Although primary aldosteronism screening is recommended in patients with treatment-resistant hypertension, diagnosis at an earlier stage of disease may prevent end-organ damage and optimize patient outcomes.

Methods: A Markov model was used to estimate the cost-effectiveness of screening for primary aldosteronism in treatment and disease (cardiovascular disease and stroke) naive hypertensive patients.

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Introduction: The putative "renal-K switch" mechanism links dietary potassium intake with sodium retention and involves activation of the sodium chloride (NaCl) cotransporter (NCC) in the distal convoluted tubule in response to low potassium intake, and suppression in response to high potassium intake. This study examined NCC abundance and phosphorylation (phosphorylated NCC [pNCC]) in urinary extracellular vesicles (uEVs) isolated from healthy adults on a high sodium diet to determine tubular responses to alteration in potassium chloride (KCl) intake.

Methods: Healthy adults maintained on a high sodium (∼4.

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Primary aldosteronism (PA), once considered a rare disease, is being increasingly recognized as an important cause of hypertension. It is associated with higher rates of cardiovascular complications compared to blood pressure-matched essential hypertension. Targeted treatments are available which can mitigate the excess cardiovascular risks and, in some cases, cure hypertension.

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Context: Primary aldosteronism (PA) and oral contraception (OC) can both cause hypertension in young women. However, the effect of OC on the screening test for PA, the aldosterone to renin ratio (ARR), is not clear.

Objective: We evaluated the impact of OC on the screening test for PA.

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Background: Elevated abundance of sodium-chloride cotransporter (NCC) and phosphorylated NCC (pNCC) are potential markers of primary aldosteronism (PA), but these effects may be driven by hypokalemia.

Methods: We measured plasma potassium in patients with PA. If potassium was <4.

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Background: Primary aldosteronism (PA) represents the most common and potentially curable cause of secondary hypertension. However, PA is not commonly screened for, and up to 34% of patients who screen positive do not complete the full diagnostic process. This suggests that the diagnostic process may pose a barrier to patients and may contribute to the under-diagnosis of PA.

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