Confirmatory testing for primary aldosteronism can misinform care
The seated saline suppression test did not accurately identify whether patients would benefit from surgery or medications for primary aldosteronism, a study of 156 patients with a positive primary screening test found.
The seated saline suppression test (SSST) for primary aldosteronism (PA) should be removed from the diagnostic care pathway, a recent study concluded.
Researchers studied 156 adults with a positive screening test result for PA to determine whether a subsequent confirmatory test with the SSST accurately diagnosed PA. The SSST was done by administering 2 L of 0.9% sodium chloride intravenously over four hours with the patient seated. Treatment response was then used as the gold standard to determine disease status. Patients were treated for PA with surgery (n=89) to remove the adrenal gland or with medications (n=67) to block its effects. Successful response was based on a large reduction in blood pressure, reduction in number of blood pressure medications, and normalization of biochemistry following treatment. The study was published May 6 by Annals of Internal Medicine.
The study found that the SSST did not discriminate between treatment responders and nonresponders: Post-SSST aldosterone concentrations overlapped between treatment responders (median, 329 pmol/L; interquartile range [IQR], 227 to 525 pmol/L]) and nonresponders (median, 255 pmol/L; IQR, 162 to 346 pmol/L). The SSST's area under the curve for discriminating response was 62.1% (95% CI, 45.1% to 79.1%) with equivocal positive and negative likelihood ratios at aldosterone cutoffs ranging from 140 to 300 pmol/L. These findings remained consistent after accounting for differences in treatment, occurrence of hypokalemia, and laboratory assay used.
According to the study authors, the results show that SSST is an unnecessary barrier to care. “Confirmatory testing with the SSST adds little to the diagnostic work-up in patients who already have a positive result on a screening test,” they wrote. “Rather, reliance on the SSST may misinform downstream treatment decisions and lead to missed opportunities for intervention, even in patients who would clearly respond to treatment. The results of our study suggest that removal of routine confirmatory testing from the diagnostic care pathway for PA may help to improve diagnostic accuracy and reduce the time needed for diagnosis and treatment for most patients.”