Aldosterone/direct renin concentration ratio as a screening test for primary aldosteronism: A meta-analysis

Optimizing the aldosterone-to-renin ratio cut-off for screening primary aldosteronism based on cardiovascular risk: a collaborative study

OBJECTIVES

Aldosterone-to-renin ratio (ARR) based screening is the first step in the diagnosis of primary aldosteronism (PA). However, the guideline-recommended ARR cutoff covers a wide range, from the equivalent of 1.3 to 4.9 ng·dl-1/mIU∙l-1. We aimed to optimize the ARR cutoff for PA screening based on the risk of cardiovascular diseases (CVD).

METHODS

Longitudinally, we included hypertensive participants from the Framingham Offspring Study (FOS) who attended the sixth examination cycle and followed up until 2014. At baseline (1995-1998), we used circulating concentrations of aldosterone and renin to calculate ARR (unit: ng·dl-1/mIU∙l-1) among 1,433 subjects who were free of CVD. We used spline regression to calculate the ARR threshold based on the incident CVD. We used cross-sectional data from the Chongqing Primary Aldosteronism Study (CONPASS) to explore whether the ARR cutoff selected from FOS is applicable to PA screening.

RESULTS

In FOS, CVD risk increased with an increasing ARR until a peak of ARR 1.0, followed by a plateau in CVD risk (hazard ratio 1.49, 95%CI 1.19-1.86). In CONPASS, when compared to essential hypertension with ARR < 1.0, PA with ARR ≥ 1.0 carried a higher CVD risk (odds ratio 2.24, 95%CI 1.41-3.55), while essential hypertension with ARR ≥ 1.0 had an unchanged CVD risk (1.02, 0.62-1.68). Setting ARR cutoff at 2.4 ~ 4.9, 10% ~30% of PA subjects would be unrecognized although they carried a 2.45 ~ 2.58-fold higher CVD risk than essential hypertension.

CONCLUSIONS

The CVD risk-based optimal ARR cutoff is 1.0 ng·dl-1/mIU∙l-1 for PA screening. The current guideline-recommended ARR cutoff may miss patients with PA and high CVD risk.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov (NCT03224312).

Radiation dosimetry of para-chloro-2-[18F]fluoroethyl-etomidate: a PET tracer for adrenocortical imaging

BACKGROUND

[11C]metomidate, a methyl ester analogue of etomidate, is used for positron emission tomography of adrenocortical cancer, and has been tested in recent clinical trials for lateralization in primary aldosteronism (PA). However, in PA, visualization as well as uptake quantification are hampered by the tracer's rather high non-specific liver uptake, and its overall clinical usefulness is also limited by the short 20-minute half-life of carbon-11. Therefore, we evaluated para-chloro-2-[18F]fluoroethyl-etomidate, [18F]CETO, a fluorine-18 (T1/2=109.8 min) analogue, as a potential new adrenocortical PET tracer. The aim of this study was to assess radiation dosimetry of [18F]CETO.

RESULTS

[18F]CETO showed a high uptake in adrenal glands, still increasing at 5 h post injection. Adrenal glands (absorbed dose coefficients 0.100 ± 0.032 mGy/MBq in males and 0.124 ± 0.013 mGy/MBq in females) received the highest absorbed dose. The effective dose coefficient was 20 µSv/MBq.

CONCLUSIONS

[18F]CETO has a favourable biodistribution in humans for adrenal imaging. The effective dose for a typical clinical PET examination with 200 MBq [18F]CETO is 4 mSv.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT05361083 Retrospectively registered 29 April 2022. at, URL: https://clinicaltrials.gov/ct2/show/NCT05361083.

Screening for Primary Aldosteronism by Mass Spectrometry Versus Immunoassay Measurements of Aldosterone: A Prospective Within-Patient Study

BACKGROUND

Measurements of aldosterone by mass spectrometry are more accurate and less prone to interferences than immunoassay measurements, and may produce a more accurate aldosterone:renin ratio (ARR) when screening for primary aldosteronism (PA).

METHODS

Differences in diagnostic performance of the ARR using mass spectrometry vs immunoassay measurements of aldosterone were examined in 710 patients screened for PA. PA was confirmed in 153 patients and excluded in 451 others. Disease classifications were not achieved in 106 patients. Areas under receiver-operating characteristic curves (AUROC) and other measures were used to compare diagnostic performance.

RESULTS

Mass spectrometry-based measurements yielded lower plasma aldosterone concentrations than immunoassay measurements. For the ARR based on immunoassay measurements of aldosterone, AUROCs were slightly lower (P = 0.018) than those using mass spectrometry measurements (0.895 vs 0.906). The cutoff for the ARR to reach a sensitivity of 95% was 30 and 21.5 pmol/mU by respective immunoassay and mass spectrometry-based measurements, which corresponded to specificities of 57% for both. With data restricted to patients with unilateral PA, diagnostic sensitivities of 94% with specificities >81% could be achieved at cutoffs of 61 and 52 pmol/mU for respective immunoassay and mass spectrometry measurements.

CONCLUSIONS

Mass spectrometry-based measurements of aldosterone for the ARR provide no clear diagnostic advantage over immunoassay-based measurements. Both approaches offer limited diagnostic accuracy for the ARR as a screening test. One solution is to employ the higher cutoffs to triage patients likely to have unilateral PA for further tests and possible adrenalectomy, while using the lower cutoffs to identify others for targeted medical therapy.German Clinical Trials Register ID: DRKS00017084.

Primary aldosteronism - a multidimensional syndrome

Primary aldosteronism is a common cause of hypertension and is a risk factor for cardiovascular and renal morbidity and mortality, via mechanisms mediated by both hypertension and direct insults to target organs. Despite its high prevalence and associated complications, primary aldosteronism remains largely under-recognized, with less than 2% of people in at-risk populations ever tested. Fundamental progress made over the past decade has transformed our understanding of the pathogenesis of primary aldosteronism and of its clinical phenotypes. The dichotomous paradigm of primary aldosteronism diagnosis and subtyping is being redefined into a multidimensional spectrum of disease, which spans subclinical stages to florid primary aldosteronism, and from single-focal or multifocal to diffuse aldosterone-producing areas, which can affect one or both adrenal glands. This Review discusses how redefining the primary aldosteronism syndrome as a multidimensional spectrum will affect the approach to the diagnosis and subtyping of primary aldosteronism.

Screening for primary aldosteronism in pregnancy

Primary aldosteronism, the most common secondary cause of hypertension is likely to be significantly underdiagnosed in pregnancy and is associated with high rates of adverse maternal and fetal outcomes. Normal pregnancy is associated with a rise in aldosterone and renin levels early in pregnancy making the aldosterone:renin ratio which is normally used to screen for primary aldosteronism, difficult to interpret. Additionally, many laboratories have moved from performing plasma renin activity to measurements of direct renin. Aldosterone, direct renin and aldosterone: renin ratios were determined in 9 women with primary aldosteronism and compared to levels in 33 women with chronic hypertension. All women with primary aldosteronism had a direct renin levels of less than 20 mU/L together with aldosterone:renin ratio of greater than 40. Values for direct renin were significantly lower, and the aldosterone:renin ratio was significantly higher in pregnancy in women with primary aldosteronism compared to women with chronic hypertension. Pregnant women with chronic hypertension who have a direct renin level less than 20 mU/L and aldosterone:renin ratio of greater than 40 should have close surveillance for maternal and fetal complications, and follow-up postpartum should be ensured for definitive testing.

Diagnosis and Management of Endocrine Hypertension in Children and Adolescents

Hypertension in childhood and adolescence has increased in prevalence. Interest in the disease was raised after the 2017 clinical practice guidelines of the American Academy of Paediatrics on the definition and classification of paediatric hypertension. Among the secondary causes of paediatric hypertension, endocrine causes are relatively rare but important due to their unique treatment options. Excess of catecholamine, glucocorticoids and mineralocorticoids, congenital adrenal hyperplasia, hyperaldosteronism, hyperthyroidism and other rare syndromes with specific genetic defects are endocrine disorders leading to paediatric and adolescent hypertension. Adipose tissue is currently considered the major endocrine gland. Obesity-related hypertension constitutes a distinct clinical entity leading to an endocrine disorder. The dramatic increase in the rates of obesity during childhood has resulted in a rise in obesity-related hypertension among children, leading to increased cardiovascular risk and associated increased morbidity and mortality. This review presents an overview of pathophysiology and diagnosis of hypertension resulting from hormonal excess, as well as obesity-related hypertension during childhood and adolescence, with a special focus on management.

Taiwan mini-frontier of primary aldosteronism: Updating detection and diagnosis

BACKGROUND

To update information about the internationally accepted standards and clinical recommendations for the detection and diagnosis of primary aldosteronism (PA).

METHODS

The Taiwan Society of Aldosteronism (TSA) Task Force reviewed the latest literature and reached a consensus after group meetings. The nine critical issues were recognized to provide updated information and internationally acceptable protocols.

RESULTS

When screening for PA by using the plasma aldosterone concentration (PAC) to plasma renin activity (PRA) ratio (ARR), withdrawal or adjustment of antihypertensive medication is not always necessary on the first patient visit. Hypokalemia should be corrected before ARR screening. In spontaneous hypokalemia, plasma renin below detection levels, and PAC higher than 20 ng/dL (550 pmol/L), further confirmatory testing is unnecessary for PA diagnosis. Direct renin concentration (DRC) could be used for PA diagnosis if PRA is unavailable. Although additional confirmatory tests are suggested, the result of a single test is still reliable. For patient safety, discontinuation or adjustment of antihypertensive medications is indicated before adrenal venous sampling (AVS). ACTH could be beneficial for successful adrenal vein cannulation but is not necessary for determining lateralization in AVS. Simultaneous technique is preferred for AVS. Adrenal NP-59 scintigraphy integrated with SPECT/CT could guide PA management.

CONCLUSION

With introduction of these new concepts to the clinicians, we expect better identification, management and treatment of PA patients.

Diagnostic Accuracy of the Aldosterone-to-Active Renin Ratio for Detecting Primary Aldosteronism

Context

The aldosterone-to-active renin ratio (AARR) is the recommended screening test for primary aldosteronism (PA), but prospective study data on its sensitivity and specificity are sparse.

Objective

To investigate the diagnostic accuracy of the AARR for detecting PA.

Design

Prospective diagnostic accuracy study.

Setting

This study was conducted from February 2009 to August 2015 at the outpatient clinic of the Department of Endocrinology and Diabetology of the Medical University of Graz, Austria.

Participants

Four hundred patients with arterial hypertension who were referred to a tertiary care center for screening for endocrine hypertension.

Intervention

Participants had a determination of the AARR (index test) and a second AARR determination followed by a saline infusion test (SIT) after 2 to 6 weeks. PA was diagnosed in individuals with any AARR ≥3.7 ng/dL/µU/mL [including a plasma aldosterone concentration (PAC) of ≥9 ng/dL] who had a PAC ≥10 ng/dL after the SIT. We did not substantially alter antihypertensive drug intake.

Main Outcome Measures

Primary outcome was the receiver-operating characteristic (ROC) curve of the AARR in diagnosing PA.

Results

A total of 382 participants were eligible for analyses; PA was diagnosed in 18 (4.7%) patients. The area under the ROC curve of the AARR in detecting PA was 0.973 (95% CI, 0.956 to 0.990). Sensitivity and specificity for a positive AARR in diagnosing PA were 100% (95% CI, 81.5% to 100.0%) and 89.6% (95% CI, 86.0% to 92.5%), respectively.

Conclusions

The AARR has good diagnostic accuracy for detecting PA.

Clinical biomarker innovation: when is it worthwhile?

Background

Choosing which biomarker tests to select for further research and development is not only a matter of diagnostic accuracy, but also of the clinical and monetary benefits downstream. Early health economic modeling provides tools to assess the potential effects of biomarker innovation and support decision-making.

Methods

We applied early health economic modeling to the case of diagnosing primary aldosteronism in patients with resistant hypertension. We simulated a cohort of patients using a Markov cohort state-transition model. Using the headroom method, we compared the currently used aldosterone-to-renin ratio to a hypothetical new test with perfect diagnostic properties to determine the headroom based on quality-adjusted life-years (QALYs) and costs, followed by threshold analyses to determine the minimal diagnostic accuracy for a cost-effective product.

Results

Our model indicated that a perfect diagnostic test would yield 0.027 QALYs and increase costs by €43 per patient. At a cost-effectiveness threshold of €20,000 per QALY, the maximum price for this perfect test to be cost-effective is €498 (95% confidence interval [CI]: €275–€808). The value of the perfect test was most strongly influenced by the sensitivity of the current biomarker test. Threshold analysis showed the novel test needs a sensitivity of at least 0.9 and a specificity of at least 0.7 to be cost-effective.

Conclusions

Our model-based approach evaluated the added value of a clinical biomarker innovation, prior to extensive investment in development, clinical studies and implementation. We conclude that early health economic modeling can be a valuable tool when prioritizing biomarker innovations in the laboratory.

Age-Related Cutoffs of Plasma Aldosterone/Renin Concentration for Primary Aldosteronism Screening

AIM

This retrospective study is aimed at investigating whether aldosterone-renin ratio (ARR) cutoffs calculated by the plasma aldosterone concentration (PAC)/plasma renin concentration (PRC) should be set differently in patients of different ages.

METHODS

521 hypertensive patients were screened for primary aldosteronism (PA) by the PAC/PRC. 174 patients diagnosed with PA and 311 patients with essential hypertension (EH) were included in the final analysis. Subjects were subdivided into four age groups: <40, 40-49, 50-59, and ≥60 years old.

RESULTS

The accuracy of the ARR varied greatly among the different age groups. An ARR of 3.7 (ng/dl)/(μIU/ml) had a sensitivity of 100% and a specificity of 80% in patients ≥ 60 years old. With this cutoff, the sensitivities in patients < 40, 40-49, and 50-59 years old were 74%, 82%, and 87%, respectively, and the specificities were 94%, 95%, and 94%, respectively. To achieve a sensitivity higher than 90%, the ARR cutoff needed to be lowered to 2.0 (ng/dl)/(μIU/ml) for patients 40-49 and 50-59 years old, resulting in sensitivities of 90% and 95%, respectively, and specificities of 80% and 84%, respectively. To achieve a sensitivity higher than 90%, the ARR cutoff needed to be lowered to 1.0 (ng/dl)/(μIU/ml) for patients < 40 years old, resulting in a sensitivity of 90% and a specificity of 82%.

CONCLUSIONS

An ARR of 3.7 (ng/dl)/(μIU/ml) is optimal for patients ≥ 60 years; for patients 40-59 years, the optimal ARR cutoff is 2.0; for those younger than 40 years, an ARR of 1.0 may be more reasonable.