Tests to Diagnose Primary Aldosteronism and Its Subtypes

Doctor With Patient Having A Computerized Axial Tomography (CAT) ScanBecause some of the typical tests to diagnose primary aldosteronism (PA) are expensive and not available in the majority of hospitals, researchers are trying to find more cost-effective ways to diagnose PA.  Right now, a diagnosis is made by screening, confirmation testing, and subtype diagnosis (CT scan and adrenal vein sampling).  Researchers looked into the role of serum 18-hydroxcoricosterone (s18OHB), urinary and serum 18-hydroxycortisol (u- and s18OHF), and urinary and serum 18-oxocortisol (u- and s8oxoF) in diagnosing PA and its subtypes (aldosterone-producing adenoma [APA] and bilateral adrenal hyperplasia [BAH]).

The results of the study were published online on January 11, 2012, and they appeared in the Journal of Clinical Endocrinology and Metabolism in March 2012.  The article is called “18-hydroxycorticosterone, 18-hydroxycortisol, and 18-oxocortisol in the diagnosis of primary aldosteronsim and its subtypes.”

There were 213 patients in the study.  They were broken out by various conditions:

  • 62 had low-renin essential hypertension (EH)
  • 81 had PA, which included 20 with APA and 61 with BAH
  • 24 had glucocorticoid-remediable aldosteronsim
  • 16 had adrenal incidentaloma
  • 30 had normotensives

The study was run by measuring s18OHB, s18OHF, and s18oxoF before and after saline load test (SLT).  The researchers also measured the 24-hour u18OHF and u18oxoF.

When looking at the results, researchers saw that, when compared to EH and normal subjects, PA patients had significantly higher levels of s18OHB, u18OHF, and u18oxoF.

Comparing APA and BAH patients showed that those with APA had significantly higher levels of s18OHB, u18OHF, u18oxoF, s18OHF, and s18oxoF.

In all the groups, SLT reduced s18OHB, s18OHF, and s18oxoF by a significant amount.  However, steroid reduction for those with APA was much less than it was for those with BAH and EH.

Also, the researchers saw that the s18OHB/aldosterone ratio following SLT more than doubled for those with EH.  However, it remained the same for APA patients.

In conclusion, the researchers could say that for PA patients with a positive aldosterone to plasma rennin activity ratio, u18OHF, u18oxoF, and s18OHB measurements correlate with confirmatory tests and adrenal vein sampling.  These results require further verification, but if they are verified, then these steroid assays may aid in refining the diagnostic workup for primary aldosteronism.

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