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New diagnostic test quickly, accurately identifies primary aldosteronism
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An overnight test for primary aldosteronism identified the condition in hypertensive adults with higher accuracy than a standard saline-loading test, according to recent study findings.
Primary aldosteronism is typically identified with a two-step process — an initial screening test, based on the serum aldosterone-to-renin ratio, followed by a confirmatory test to document autonomous aldosterone secretion.
“Currently available diagnostic tests for [primary aldosteronism] are complex, time-consuming [and] relatively expensive and, therefore, cannot be applied widely in primary care units,” Vaios Tsiavos, MD, of the department of endocrinology and diabetes center at Athens General Hospital in Athens, Greece, and colleagues wrote. “In order to overcome these limitations, we opted to develop a new, rapid overnight diagnostic test for [primary aldosteronism] aimed at suppressing the renin-angiotensin-aldosterone system (RAAS) with appropriately targeted drugs, such as captopril and valsartan, and concomitantly suppress [adrenocorticotropic hormone] secretion with the administration of dexamethasone.”
Researchers analyzed data from 148 adults aged 31 to 71 years who were evaluated for hypertension between 2011 and 2015 (mean age, 54 years; mean systolic blood pressure, 139.3 mm Hg; mean diastolic BP, 85.06 mm Hg; mean BMI, 29.25 kg/m²). Patients underwent a fludrocortisone-dexamethasone suppression test (FDST) and the new overnight diagnostic test (DCVT) using a RAAS blockade with dexamethasone, captopril and valsartan. Tests were performed at least 7 days apart.
Within the cohort, 45 patients were diagnosed with primary aldosteronism; all normalized their elevated BP after administration of spironolactone or eplerenone. The remaining 103 patients were diagnosed with essential hypertension and served as controls.
Using receiver operating characteristic (ROC) analysis, the corresponding sensitivity and specificity for the post-DCVT aldosterone-to-renin ratio were 98% and 89%, respectively, and 100% and 82% for the post-DCVT aldosterone level, with selected cutoffs of 0.3 ng/dL/U/mL and 3.1 ng/dL, respectively.
However, considering the cutoffs simultaneously, the estimated sensitivity and specificity were 98% and 100%, respectively, according to researchers. They noted that, when applying the cutoffs, diagnosis with the DCVT test of primary aldosteronism was confirmed in 44 of the 45 patients who were considered to have the disease, including four patients in whom the FDST failed initially to confirm the diagnosis.
“This suggests that basal [aldosterone-to-renin ratio] as a screening test may diagnose only the more severe cases, leaving undiagnosed the milder forms of [primary aldosteronism],” the researchers wrote. “We [find] that the diagnostic limitations which are related to the two-step procedure (screening and confirmatory tests) can be overcome using as a screening-diagnostic test the DCVT, which, as the present study shows, is a simple and very low-cost test, with similar sensitivity and specificity compared to FDST.” – by Regina Schaffer
Disclosure: The researchers report no relevant financial disclosures.
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