Comparison of Confirmatory Tests for the Diagnosis of Primary Aldosteronism

University of Verona, Verona, Veneto, Italy
Journal of Clinical Endocrinology & Metabolism (Impact Factor: 6.21). 07/2006; 91(7):2618-23. DOI: 10.1210/jc.2006-0078
Source: PubMed


Primary aldosteronism (PA) is the most frequent form of secondary hypertension, accounting for up to 5-10% of all hypertensive patients, and the diagnosis of PA can present an important challenge for the clinician. After a positive screening test, the diagnosis is confirmed by a suppression test, often an iv saline load test (SLT) or a fludrocortisone suppression test (FST). The FST is considered by many to be the most reliable but is more complex and expensive.
Our objective was to compare the specificity of SLT with FST for the diagnosis of PA.
The study included 100 hypertensive patients referred to hypertension units with suspected PA after the screening test.
All patients underwent FST and SLT.
We assessed plasma aldosterone concentrations (PAC) before and after FST and SLT.
After iv SLT, 10.4% of the PA patients were negative and 16.1% of patients with essential hypertension were positive after SLT; that is, a correct diagnosis with SLT was obtained in 88% of patients compared with FST. PAC after SLT and PAC after FST were highly correlated (P < 0.0001). Receiver operator characteristic curve analysis demonstrated that the best cutoff for PAC after SLT was 5 ng/dl. Patients with aldosterone-producing adenoma displayed a smaller reduction of PAC compared with patients with bilateral adrenal hyperplasia; a PAC after SLT greater than 6 ng/dl identified all patients eventually diagnosed as having aldosterone-producing adenoma.
This study demonstrates that the iv SLT is a reasonably good alternative to the more expensive and complex FST for the diagnosis of PA after a positive screening test.

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Available from: Giuseppe Regolisti
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    • "If the ARR shows pathological values, an autonomous aldosterone secretion should be considered, which needs to be substantiated by independent confirmation tests. These tests include the measurement of the aldosterone metabolites in 24h urine samples and the normal saline load test, where 2l of isotonic NaCl 0.9% are infused over 4 hours followed by blood sampling for the measurement of aldosterone concentration (Mulatero et al., 2006). An additional confirmation test, not often used in routine testing, is the fludrocortisone suppression test. "

    Full-text · Article · Jun 2009
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    • "Our study population consists of patients with a high probability of PA, thus justifying an extensive screening procedure for this disease in view of the fact that patients with PA are at excess risk of cardiovascular disease which can be significantly reduced by a targeted treatment in diseased patients [1]. The SIT is considered a safe confirmatory test and previous studies have shown no significant side effects apart from occasionally observed increases in blood pressure that could all be well controlled [1-3,21,34]. Towards this, we want to note that blood pressure and heart rate will be regularly (all 30 minutes) measured during the SIT. "
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    ABSTRACT: Primary aldosteronism (PA) affects approximately 5 to 10% of all patients with arterial hypertension and is associated with an excess rate of cardiovascular complications that can be significantly reduced by a targeted treatment. There exists a general consensus that the aldosterone to renin ratio should be used as a screening tool but valid data about the accuracy of the aldosterone to renin ratio in screening for PA are sparse. In the Graz endocrine causes of hypertension (GECOH) study we aim to prospectively evaluate diagnostic procedures for PA. In this single center, diagnostic accuracy study we will enrol 400 patients that are routinely referred to our tertiary care center for screening for endocrine hypertension. We will determine the aldosterone to active renin ratio (AARR) as a screening test. In addition, all study participants will have a second determination of the AARR and will undergo a saline infusion test (SIT) as a confirmatory test. PA will be diagnosed in patients with at least one AARR of >or= 5.7 ng/dL/ng/L (including an aldosterone concentration of >or= 9 ng/dL) who have an aldosterone level of >or= 10 ng/dL after the saline infusion test. As a primary outcome we will calculate the receiver operating characteristic curve of the AARR in diagnosing PA. Secondary outcomes include the test characteristics of the saline infusion test involving a comparison with 24 hours urine aldosterone levels and the accuracy of the aldosterone to renin activity ratio in diagnosing PA. In addition we will evaluate whether the use of beta-blockers significantly alters the accuracy of the AARR and we will validate our laboratory methods for aldosterone and renin. Screening for PA with subsequent targeted treatment is of great potential benefit for hypertensive patients. In the GECOH study we will evaluate a standardised procedure for screening and diagnosing of this disease.
    Full-text · Article · May 2009 · BMC Endocrine Disorders
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