Baseline Plasma Aldosterone Level and Renin Activity Allowing Omission of Confirmatory Testing in Primary Aldosteronism

Sparing confirmatory testing in primary aldosteronism (SCIPA): a multicenter retrospective diagnostic accuracy study

BACKGROUND

The diagnosis of primary aldosteronism (PA) is comprehensive, which includes case-detection testing, case confirmation followed by subtype classification. In certain instances, such as in the setting of spontaneous hypokalemia, suppressed renin activity (PRA) plus plasma aldosterone concentration (PAC) of > 15 ng/dL, one may not proceed with confirmatory tests. However, the quality of evidence behind this approach is very low. This study sought to evaluate the proposed "simplified confirmatory pathway" that can spare confirmatory testing for primary aldosteronism by evaluating the diagnostic performances of the various pre-specified PAC thresholds in combination with findings of suppressed renin and spontaneous hypokalemia.

METHODS

This is a multi-center, retrospective diagnostic accuracy cohort-selected cross-sectional study. A total of 133 participants aged 18 years and above underwent saline infusion test between January 2010 to March 2024. The outcome measures comprise of the diagnostic performances of the different index test combinations (baseline PAC, baseline PRA and presence of spontaneous hypokalemia): sensitivity, specificity, negative predictive value, positive predictive value, positive likelihood ratio, negative likelihood ratio, and diagnostic accuracy. Data analysis was performed using SPSS 29.0.1.0 & MedCalc 20.218.

RESULTS

Of the 133 patients who underwent saline infusion test, 88 (66.17%) were diagnosed with PA. A PAC of > 25 ng/dL plus PRA < 1.0 ng/dL/hr with spontaneous hypokalemia showed the highest specificity at 100% (95% CI 90.51%, 100.00%) and positive predictive value at 100% (85.18 - 100.00%). The minimum acceptable combination criteria were determined to be a PAC of > 20 ng/dL plus PRA < 0.6 ng/dL/hr, and presence of spontaneous hypokalemia. It has high specificity (94.59%; 95% CI 81.81%, 99.34%), positive predictive value (93.55%, 95% CI 78.49%, 98.29%), and moderate positive likelihood ratio (LR+) (6.39, 95% CI 1.61, 25.38) CONCLUSION: A hypertensive patient with spontaneous hypokalemia and screening findings of PAC > 20 ng/dL and suppressed PRA of < 0.6 ng/ml/hr, may be classified as "overt primary aldosteronism confirmed" and may not need to proceed with dynamic confirmatory testing.

PROTOCOL REGISTRATION NUMBER

SRCTN34186253.

The role of confirmatory tests in the diagnosis of primary aldosteronism

Confirmatory tests for diagnosis of primary aldosteronism (PA) play an important role in sparing patients with a false-positive aldosterone-to-renin ratio (ARR) screening test from undergoing invasive subtyping procedures. We recommend that patients with a positive ARR test should undergo at least one confirmatory test to confirm or exclude the diagnosis of PA before directly proceeding to subtype studies, except for patients with significant PA phenotypes, including spontaneous hypokalemia, plasma aldosterone concentration >20 ng/dL plus plasma renin activity below a detectable level. Although a gold standard confirmatory test has not been identified, we recommend that saline infusion test and captopril challenge test, which were widely used in Taiwan. Patients with PA have been reported to have a higher prevalence of concurrent autonomous cortisol secretion (ACS). ACS is a biochemical condition of mild cortisol overproduction from adrenal lesions, but without the typical clinical features of overt Cushing's syndrome. Concurrent ACS may result in incorrect interpretation of adrenal venous sampling (AVS) and may lead to adrenal insufficiency after adrenalectomy. We recommend screening for ACS in patients with PA scheduled for AVS examinations as well as for adrenalectomy. We recommend the 1-mg overnight dexamethasone suppression test as screening method to detect ACS.

Japan Endocrine Society clinical practice guideline for the diagnosis and management of primary aldosteronism 2021

Primary aldosteronism (PA) is associated with higher cardiovascular morbidity and mortality rates than essential hypertension. The Japan Endocrine Society (JES) has developed an updated guideline for PA, based on the evidence, especially from Japan. We should preferentially screen hypertensive patients with a high prevalence of PA with aldosterone to renin ratio ≥200 and plasma aldosterone concentrations (PAC) ≥60 pg/mL as a cut-off of positive results. While we should confirm excess aldosterone secretion by one positive confirmatory test, we could bypass patients with typical PA findings. Since PAC became lower due to a change in assay methods from radioimmunoassay to chemiluminescent enzyme immunoassay, borderline ranges were set for screening and confirmatory tests and provisionally designated as positive. We recommend individualized medicine for those in the borderline range for the next step. We recommend evaluating cortisol co-secretion in patients with adrenal macroadenomas. Although we recommend adrenal venous sampling for lateralization before adrenalectomy, we should carefully select patients rather than all patients, and we suggest bypassing in young patients with typical PA findings. A selectivity index ≥5 and a lateralization index >4 after adrenocorticotropic hormone stimulation defines successful catheterization and unilateral subtype diagnosis. We recommend adrenalectomy for unilateral PA and mineralocorticoid receptor antagonists for bilateral PA. Systematic as well as individualized clinical practice is always warranted. This JES guideline 2021 provides updated rational evidence and recommendations for the clinical practice of PA, leading to improved quality of the clinical practice of hypertension.

Subtype-specific trends in the clinical picture of primary aldosteronism over a 13-year period

OBJECTIVE

Primary aldosteronism has two main clinically and biologically distinct subtypes: unilateral aldosterone-producing adenoma (APA) and bilateral adrenal hyperplasia (BAH). We aimed to evaluate the changes of each subtype's clinical characteristics over a 13-year period.

METHODS

This retrospective study involved time-trend analyses to identify changes in the clinical features of APA and BAH at diagnosis (2006-2018). A nationwide database from 41 Japanese referral centers was searched, which identified 2804 primary aldosteronism patients with complete baseline information and adrenal venous sampling (AVS) data.

RESULTS

The proportion of patients with APA decreased from 51% in 2006-2009 to 22% in 2016-2018. Among the 1634 patients with BAH, trend analyses revealed decreases in hypertension duration (median 7--3 years; P < 0.01) and hypokalemia prevalence (18--11%; P < 0.01). However, among the 952 patients with APA, there were no significant changes in hypertension duration (median 8 years) and hypokalemia prevalence (overall 70%). Furthermore, the APA group had a trend towards increased use of multiple hypertensive drugs at diagnosis (30--43%; P < 0.01). When subtypes were reclassified according to the precosyntropin stimulation AVS data, APA patients tended to be diagnosed earlier and at milder forms, consistent with the trend in overall primary aldosteronism patients.

CONCLUSION

During 2006-2018, we identified marked subtype-specific trends in the clinical findings at the diagnosis of primary aldosteronism. Our results suggested that the emphasis on the implementing cosyntropin stimulation during AVS might lead to under-identification of APA, especially in patients with mild or early cases.

Prevalence, Subtype Classification, and Outcomes of Treatment of Primary Aldosteronism: A Prospective Study in China

OBJECTIVE

To investigate the prevalence of primary aldosteronism (PA) among participants with hypertension, evaluate the concordance of PA classification between adrenal computed tomography and adrenal venous sampling, and compare the outcomes of surgery and medication for unilateral PA.

METHODS

A prospective study was conducted among all inpatients with hypertension (n = 7594) at the National Center for Cardiovascular Diseases, China, from May 2016 to April 2018.

RESULTS

Of the 7594 participants, 8.12% (n = 617) with plasma aldosterone-renin ratio ≥3.7 were possible PA cases. Three hundred sixty-seven cases with plasma aldosterone-renin ratio ≥3.7 and plasma aldosterone concentration ≥10 ng/dL were confirmed using the recumbent saline infusion test (69.20%, 182 of 263) or the captopril challenge test (66.5%, 69 of 104, P > .05). The prevalence of PA was 3.31% (n = 251). Of the 251 patients with PA, all of them had multiple comorbidities, and 49.40% (n = 124) had spontaneous hypokalemia. The concordance of PA classification between adrenal computed tomography and adrenal venous sampling was only 47.11%. The patients' blood pressure declined to normal ranges in the adrenalectomy (85.71%, 30 of 35) and spironolactone (63.04%; 29 of 46) groups (P < .05). Furthermore, hypokalemia was normalized in the adrenalectomy (100.00%; 26 of 26) and spironolactone (94.74%; 18 of 19) groups.

CONCLUSION

It is necessary to incorporate PA screening into routine practice for those with hypertension in the Chinese population. This will assist in ensuring that the best therapeutic schedule based on PA subtypes is devised. Additionally, as a result, it may contribute to restoring the blood pressure levels and reducing the prevalence of comorbidities in these patients with PA.

Development and Validation of Criteria for Sparing Confirmatory Tests in Diagnosing Primary Aldosteronism

CONTEXT

The Endocrine Society Guidelines for the diagnosis of primary aldosteronism (PA) suggest that confirmatory tests (CFT) are not required when the following criteria are met: plasma aldosterone concentration (PAC) is >20 ng/dL, plasma renin is below detection levels, and hypokalemia is present. The evidence for the applicability of the guideline criteria is limited.

OBJECTIVE

To develop and validate optimized criteria for sparing CFT in the diagnosis of PA.

DESIGN AND SETTING

The optimized criteria were developed in a Chinese cohort using the captopril challenge test, verified by saline infusion test (SIT) and fludrocortisone suppression test (FST), and validated in an Australian cohort.

PARTICIPANTS

Hypertensive patients who completed PA screening and CFT.

MAIN OUTCOME MEASURE

Diagnostic value of the optimized criteria.

RESULTS

In the development cohort (518 PA and 266 non-PA), hypokalemia, PAC, and plasma renin concentration (PRC) were selected as diagnostic indicators by multivariate logistic analyses. The combination of PAC >20 ng/dL plus PRC <2.5 μIU/mL plus hypokalemia had much higher sensitivity than the guideline criteria (0.36 vs 0.11). The optimized criteria remained superior when the SIT or FST were used as CFT. Non-PA patients were not misdiagnosed by either criteria, but the percentage of patients in whom CFT could be spared was higher with the optimized criteria. In the validation cohort (125 PA and 81 non-PA), the sensitivity of the optimized criteria was also significantly higher (0.12 vs 0.02).

CONCLUSIONS

Hypertensive patients with PAC >20 ng/dL, PRC <2.5 μIU/mL, plus hypokalemia can be confidently diagnosed with PA without confirmatory tests.