the validity of tetrahydroaldosterone as a screening test for PA

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American Journal of Hypertension, Volume 16, Issue 7, July 2003, Pages

522-530

Saleh Abdelhamid, Roland Blomer, Gerhard Hommel, Doris Haack, Sabina

Lewicka, Fiegel, Bernd Krumme

a Hypertension and Nephrology Unit (SA, RB, PF, BK), Deutsche Klinik f¨¹r

Diagnostik and Klaus Ketzler Institute, Wiesbaden, Germany b Institute for

Medical Biometry (GH), Epidemiology and Informatics, University of Mainz,

Mainz, Germany c Department of Pharmacology (DH, SL), University of

Heidelberg, Heidelberg, Germany

Urinary tetrahydroaldosterone as a screening method for primary

aldosteronism: a comparative study

Abstract

Background

The major aldosterone metabolite 3¦Á,5¦Â tetrahydroaldosterone reflects up

to 45% of the aldosterone secretion. Its 24-h urinary excretion is likely to

provide an accurate index of the daily aldosterone production and to be an

indicator for primary aldosteronism (PA).

Methods

In a prospective study, the validity of tetrahydroaldosterone as a screening

test for PA was evaluated in comparison to serum potassium, plasma

aldosterone, plasma renin activity, plasma aldosterone/renin activity ratio

(PARR), as well as 24-h urinary aldosterone-18-glucuronide and free

aldosterone. A total of 111 normotensive individuals, 412 PA patients and

1453 essential hypertensive patients, were studied. The effect of blood

sampling technique on potassium level was also investigated.

Results

Tetrahydroaldosterone differentiated PA from essential hypertension with a

sensitivity of 96% and a specificity of 95%. The sensitivity was 89% for

plasma aldosterone, 87% for free aldosterone, 85% for PARR, 71% for

aldosterone-18-glucuronide and 51% for renin activity. Specificities varied

between 91% and 85%. The combined use of the parameters plasma aldosterone

¡Ý9.0 ng/dL and PARR ¡Ý25 resulted in a sensitivity of 82% and specificity

of 95%. Forearm exercise proved to be a source of erroneous elevations of

potassium sufficient to obscure the suspicion of PA.

Conclusion

The data suggest that tetrahydroaldosterone is the most reliable screening

test for PA. Tetrahydroaldosterone determination in combination with

aldosterone-18-glucuronide and free aldosterone increases diagnostic

specificity for PA. Potassium, renin, plasma aldosterone, and basal PARR are

inadequate screening procedures because they are subject to high rates of

false-positive and false-negative results.