The importance of not overlooking curable hypertension

In the current issue of the Journal of Hypertension, Mulatero and colleagues [1] addressed the important issue of a potentially curable form of hypertension being overlooked. They did this in a novel and very interesting way by exploring the attitudes of general practitioners (GPs) in Italy and Germany to screening hypertensive patients for primary aldosteronism, arguably the commonest potentially curable form of hypertension. Web-based interviews were conducted between November 2013 and January 2014 to document the GP's experience with hypertensive patients. The aim was to discover, first, how knowledgeable 250 GPs in Italy and 250 GPs in Germany were regarding appropriate screening for primary aldosteronism, by testing their familiarity with the Endocrine Society Guidelines produced by acknowledged experts in management of primary aldosteronism and published in 2008 [2]; and second, whether the GPs were employing the guidelines in their regular care of hypertensive patients. Considering that a number of experts in primary aldosteronism screening and management are based in Italy and Germany, countries with well established healthcare systems, and that the Guidelines had been widely discussed at meetings in those countries, the authors found the results disappointing. Although, the GPs were usually aware that the Guidelines existed, they were not following them. For example, the Guidelines encourage screening for primary aldosteronism in moderately severe hypertension, which was commonly encountered by the GPs, but did not attract measurements of aldosterone and renin. The authors point out that the cost of renin and aldosterone measurements are not high and are easily outweighed by the savings accompanying appropriate treatment. The GPs appeared to be unaware of the advantage of making these measurements before commencing medications, which make their interpretation more difficult. Perhaps even more surprisingly, levels of potassium and creatinine were not routinely measured. The study is well written, the abstract is an excellent summary, and the results are discussed in great detail, seeking explanations for lack of impact of the Guidelines, and exploring a way forward. Any conclusions reached, as a result of this study, depend on a reasonable assumption that the sample of GPs participating in the questionnaire was representative and that their answers were the result of serious consideration. The GPs who participated were compensated for time lost to patient care. The authors discuss these aspects and acknowledge that future guidelines might have to be less complicated, and indicate that a desk reference module might accompany the revised guidelines. The authors discuss the possible very high prevalence of primary aldosteronism suggested by some recent studies. This depends on acceptance of the diagnosis of primary aldosteronism, not only in its common normokalemic form but also when aldosterone, renin, and even blood pressure (BP) are normal, the diagnosis depending on demonstration that aldosterone is unsuppressed when its important regulator, renin is suppressed. Aldosterone responses to fluctuating levels of adrenocorticotrophic hormone may be part of the explanation. Given that hypertension is a very common chronic disease worldwide resulting in high morbidity and great cost to healthcare systems and the economy in general, its adequate management is for many reasons of very great importance. How can this be achieved? The answer is surely better education of all doctors in the management of hypertension, including how to identify those patients with a specifically treatable cause, such as primary aldosteronism. For example, earlier teaching had been that primary aldosteronism was a rare and relatively benign cause of hypertension. As discussed by Mulatero and colleagues [1], there is good evidence that primary aldosteronism is not uncommon and is a significant contributor to resistant hypertension. The high prevalence and high costs of hypertension demand a prominent place for it in undergraduate medical curricula and also in the postgraduate training of endocrinologists, cardiologists, nephrologists, and general physicians, in particular. All doctors need to be aware that primary aldosteronism is not uncommon, and is associated with morbidity in excess of that explained by the level of BP. This makes early diagnosis especially important. They also need to be aware that primary aldosteronism is relatively and sometimes absolutely resistant to treatment with the usual antihypertensive medications but very responsive to specific treatment with aldosterone antagonists, such as spironolactone, eplerenone, and amiloride, often in quite small doses. Surprisingly, while the GPs taking part in the study were accustomed to dealing with resistant hypertension, they appeared to be unaware of the efficacy of aldosterone antagonists in resistant hypertension and were not using them. This led Mulatero and colleagues [1] to speculate whether the best short-term solution to the problem of missed or poorly treated primary aldosteronism and resistant hypertension in general might be to introduce a low-dose aldosterone antagonist in first-line treatment of all hypertension. Unfortunately, an excellent BP and biochemical response to this in all forms of primary aldosteronism would make unilateral aldosterone-producing adenoma (APA) more difficult to recognize, even if imaging were performed, thus depriving some patients of a possible surgical cure. To establish a diagnosis of primary aldosteronism because of APA among patients responsive to aldosterone antagonists would require weaning them all off these medications before further investigation. Another consideration which makes this approach less attractive is the serious risk of hyperkalemia when older patients with moderately severe hypertension and reduced renal function are exposed to aldosterone antagonists. The results of the study are discussed in detail, including the unexpectedly low level of routine investigation of hypertensive patients by the GPs of both countries, with plasma creatinine, potassium, aldosterone, and renin not routinely measured, despite many GPs having patients with primary aldosteronism under their care. Mulatero and colleagues [1] wondered whether there might be a shortage of appropriate specialists to whom primary aldosteronism patients identified by the GPs could be referred for further testing such as the difficult and controversial adrenal venous sampling, which is essential to unequivocally identify a unilateral and possibly curable cause, such as APA. Deficiencies in management will vary from place to place so that appropriate corrective measures will also vary and require careful consideration and wide consultation. A more attractive approach would be to work towards greater prominence of hypertension, and especially its specifically treatable and potentially curable causes, in undergraduate and postgraduate medical curricula. Coupled with this, recognition of ‘hypertension’ as a specialty within internal medicine, alongside cardiology, endocrinology, nephrology, and general medicine, which is already in progress in some countries, should ensure no shortage of experts to whom patients requiring sophisticated investigations can be referred, and should give primary aldosteronism and other specifically treatable causes of hypertension the attention they deserve. Only then can early identification and specific treatment of them bring its rich rewards. ACKNOWLEDGEMENTS Conflicts of interest There are no conflicts of interest.