Comparison of 24-h Urinary Aldosterone Level and Random Urinary Aldosterone-to-Creatinine Ratio in the Diagnosis of Primary Aldosteronism

Che-Hsiung Wu,Ya-Hui Hu,Yao-Chou Tsai,Yen-Hung Lin,Vin-Cent Wu,Kwan-Dun Wu,Ya-Wen Yang,Szu-Chun Hung,Ko-Lin Kuo,Jason Mulvenna

doi:10.1371/journal.pone.0067417

Abstract

BackgroundHistorically, urinary aldosterone level measurement was a commonly employed confirmatory test to detect primary aldosteronism (PA). However, 24-h urine collection is inconvenient and cumbersome. We hypothesized that random urinary aldosterone measurements with correction for creatinine concentration might be comparable to 24-h urinary aldosterone levels (Uald-24 h) in the diagnosis of PA.MethodsThe non-concurrent prospective study was conducted between June 2006 and March 2008 in patients admitted for confirmation of aldosteronism by salt loading test. A 24-h urine sample, which was collected during hospitalization on the day before saline infusion testing after restoration of serum hypokalemia, was collected from all subjects. Moreover, participants were asked to collect a first bladder voiding random urine sample during clinic visits. Uald-24 h and the random urinary aldosterone-to-creatinine ratio (UACR) were calculated accordingly.ResultsA total of 102 PA patients (71 patients diagnosed of aldosterone-producing adenoma, 31 with idiopathic hyperaldosteronism) and 65 patients with EH were enrolled. The receiver operating characteristic curve showed comparable areas under the curves of UACR and Uald-24 h. The Bland-Altman plot showed mean bias but no obvious heteroscedasticity between the two tests. When using random UACR >3.0 ng/mg creatinine as the cutoff value, we obtained a specificity of 90.6% to confirm PA from essential hypertension.ConclusionsOur study reinforce that the diagnostic accuracy of random UACR was comparable to that of Uald-24 h in PA patients. With the quickness and simplicity of the UACR method and its equivalence to Uald-24 h, this assay could be a good alternative diagnostic tool for PA confirmation.

Highlights

Primary aldosteronism (PA), characterized by autonomous production of aldosterone, is a common potentially curable disease of secondary hypertension [1]
Patient Characteristics A total of 167 hypertensive patients completed the salt loading test and Uald-24 h evaluation. 102 patients had a diagnosis of primary aldosteronism (PA), 71 had aldosterone-producing adenomas (APA), and 31 had Idiopathic hyperaldosteronism (IHA)
There were no differences in gender, systolic blood pressure, diastolic blood pressure, and body mass index (BMI) between the PA and essential hypertension (EH) patients

Summary

Introduction

Primary aldosteronism (PA), characterized by autonomous production of aldosterone, is a common potentially curable disease of secondary hypertension [1]. The urinary aldosterone level was a commonly employed test for PA diagnosis [10]. The variation in aldosterone excretion throughout the day may negate the use of concentration measurements in random urine collections. We hypothesized that when properly interpreted by accounting for the effect of different rates of creatinine excretion, the random urinary aldosterone-tocreatinine ratio (UACR) might enable the diagnosis of PA in concordance with the Uald-24 h. Urinary aldosterone level measurement was a commonly employed confirmatory test to detect primary aldosteronism (PA). We hypothesized that random urinary aldosterone measurements with correction for creatinine concentration might be comparable to 24-h urinary aldosterone levels (Uald-24 h) in the diagnosis of PA

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Conclusion