Risk factors

Is it time for primary aldosteronism screening?

Specialists who deal with the complications of hypertension should be encouraging GPs in their referral network to screen newly diagnosed hypertensive patients for primary aldosteronism.

A Perspective article in the MJA has called for active screening for primary aldosteronism in patients diagnosed with hypertension before they have started on blood pressure drugs that can confound the screening test.

Co-author Dr Jun Yang, an endocrinologist at Monash Health and research fellow at the Hudson Institute of Medical Research, said screening using the aldosterone to renin ratio (ARR) has had very poor uptake in general practice.

She said during the BEACH study, which ran for over 16 years and comprised more than 1.5 million GP consultations, screening for primary aldosteronsim was ordered only 66 times.

Notably, 57 of those patients were diagnosed with primary aldosteronism.

“It’s a clear indication that we are not looking for it,” Dr Yang said. “It’s curious why the message hasn’t been getting through but very few GPs are screening.”

“All the medications can interfere with the blood test so when they are first diagnosed, before they start treatment is a perfect time to screen them. Whereas if you wait for one or two or three or four blood pressure tablets to be added, by that stage, sometime the GP or the specialists don’t even now how to screen anymore because all these tablets interfere with the result.”

She said taking people off agents for screening purposes was time consuming and possibly even dangerous if the patient had other comorbidities that required the ACE inhibitor or beta-blocker.

The MJA article suggested weak or absent guideline recommendations and lack of cost-effectiveness data were likely to be some of the factors contributing to the poor uptake of screening.

“There are no cost-effectiveness studies to show that it really is cost effective to screen every hypertensive patients for the disease even thought intuitively, just based on the pathology of the disease and the excellent treatment available, one would assume that it is cost effective,” Dr Yang told the limbic.

“We are doing a study at the moment in primary care to try and address these questions and hopefully with more solid data the guidelines can be changed but in the meantime just by educating the doctors in the Monash catchment area, our own detection rate has certainly gone up.”

Dr Yang said not everybody who returned a positive screening test for primary aldosteronism had to go through the formal diagnostic procedures.

“So there are some patients who may be older or they have comorbidities that make it difficult for them to have the whole diagnostic process. In that case you can look at the ARR and get an idea that they have this aldosterone driven hypertension in which case just giving them a bit of spironolactone, an aldosterone blocker, would be the most suitable medical treatment.”

“Of course in the ideal world we would pick these patients up early when they have newly diagnosed hypertension – we would screen them and find the disease and treat it appropriately right there and then rather than waiting until it is too late.”

She said the PATHWAY trial had shown that showed spironolactone was the most effective adjunctive therapy for patients with resistant hypertension.

However her point was that doctors should be considering primary aldosteronism early as a very common cause of potentially curable hypertension.

“Catching it early would seem to be the most cost-effective way. There are certainly a lot of patients who have well characterised primary aldosteronism who are not being diagnosed at the moment.”

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