Is this why your blood pressure drugs aren’t working?

Most days a parcel will arrive at my house containing products a PR company would like me to try, love and write about. The selection can be quite random: I receive supplements for toddlers, pregnant women, and the elderly – none of which I can use. But with yesterday’s post came a very pleasant surprise – a blood pressure monitor and a new supplement, ProKardia, said to help circulation and lower blood pressure… I must try it. I do not meet the official guidelines for high blood pressure (140/90) – but I am not far off (at 140/84 last time I was tested), and experts now say the systolic (top) figure is the one to worry about most.

Will I take drugs if I ever have to? Almost certainly – blood pressure is a major risk for stroke.

But, for some people, the drugs don’t work – and this week in the Daily Mail    I wrote about one of the lesser known reasons for this: a condition called Conn’s Disease…

High blood pressure is usually symptomless and, like most people, Susan Thornton only discovered by chance that hers was above the desirable level of 120/80 during a routine check up with her GP.

‘The doctor didn’t tell me what the reading was, just that it was above average and, though I didn’t need to take a drug, he suggested I tried losing a bit of weight and taking more exercise to bring it down.’

This was three years ago, and Susan, then 45, took her GP’s advice on board. ‘I had a pool erected in the garden, and started swimming,’ she says. ‘I felt great - until, one afternoon, halfway through a fifteen minute drive from home to collect my then partner from work, I suddenly felt extremely ill and had to pull over.

‘I had mild chest pains and feared something was happening to my heart, but the overriding sensation was that I was passing out and was going to die.’

Susan ended up being blue-lighted by ambulance to Peterborough District Hospital where staff were waiting to treat her. Her blood pressure, which had read 200/104 en route to A&E had gone off the digital scale by the time she arrived. And, although blood tests and an ECG found nothing wrong and indeed Susan’s blood pressure had returned to a more normal level by the next day when she was discharged, this turned out to be no one-off event.

‘I was put on the ACE inhibitor Ramipril to keep my blood pressure more stable after the incident, but had a total of eight similar ambulance admissions to hospital over the next eighteen months – each time with my blood pressure measuring 170/90, way higher than it should be for someone taking drugs to control it.’

10 million adults in the UK have high blood pressure (hypertension), with one in five finding, like Susan, that the usual drugs are of little help. This “resistant hypertension” is frustrating for them – and also for their GPs, struggling to cope with the problem.

High blood pressure is the leading cause of stroke, with the risk doubling with every 20 point (or mm) rise in systolic blood pressure (the top measurement) over 115.

But, for at least 10 per cent of these resistant cases (around 200,000 in the UK), there is likely to be a treatable cause that is too often overlooked: a condition called hyperaldosteronism – meaning that the adrenal glands are producing too much of the hormone aldosterone.

High levels of this hormone cause the body to retain salt, notoriously linked to high blood pressure, explains Professor Morris Brown of Addenbrookes Hospital, Cambridge. ‘Instead of getting rid of salt, the body hangs onto it in exchange for potassium – the very mineral needed to balance and normalise blood pressure – which is pushed out of the body, so exacerbating the problem.

‘The condition can be caused by benign tumours or nodules, known as Conn’s adenomas, on one or both adrenal glands – these are the glands responsible for producing our fight or flight stress hormones (eg cortisol and adrenalin as well as aldosterone) and sit just above our kidneys,’ says Professor Brown.

‘Most doctors have been trained up to believe that hyperaldosteronism affects just one per cent of people with hypertension, and, because it is considered extremely rare, it is often not looked for and only discovered by chance during a scan looking for something completely different.’

This is exactly what happened to Susan - after she was referred for an angiogram by a consultant who suspected the regular collapses were due to a problem with her heart. ‘It turned out that my heart was fine – but the angiogram caused some bleeding under my skin, and what looked suspiciously like an aneurysm, which had to be checked out with a CT scan,’ Susan says.

‘And it was this scan that showed up the 17mm lump on my left adrenal gland, and the diagnosis of Conn’s syndrome by my physician Dr Mark Gurnell at Addenbrookes Hospital.’

Susan had the adrenal gland removed by keyhole surgery in February 2012, and has had textbook blood pressure of 120/80, or lower, ever since.

‘I haven’t taken a single Ramipril, or any other blood pressure drug, since the operation and I am so relieved to be free of their side effects: they made me generally lethargic and unwell, and so low that I could barely function.

‘Once I’d come off the drugs, I felt like I’d come back from a very long journey and found myself again.’

At least ten per cent of cases of resistant hypertension are caused by Conn’s tumours like Susan’s, according to Professor Brown, but often the tumour is much smaller than hers, and easily missed on a routine CT scan. ‘A further 10-15% may still have Conn’s disease, but with microscopic nodules in both adrenals that currently make surgery inappropriate.’

Because the special scans to locate Conn’s nodules are expensive, and would rarely turn up trumps if used in all hypertensive patients, Professor Brown recommends the scans only in patients who have been diagnosed with Conn’s and are likely to benefit from surgery. Young patients (aged under 45) with consistently high blood pressure after 24 hour monitoring (a systolic of 140-160, or a diastolic over 100) should have a £15 blood test to check levels of the kidney hormone renin which are almost always suppressed in this condition, and are a good indicator of it.

‘If renin is low, then a further blood test costing about £25 can check aldosterone levels, and then scans can look for tumours.’

For those who have high aldosterone without tumours (and also those with tumours who don’t want surgery, or those with tumours on both glands, who therefore cannot benefit from surgery) there is another option: a drug – spironolactone, which is cheap but has side effects (such as breast tissue) in men, or eplerenone, costing £40-80 a month - to block the aldosterone.

Charles Payne, 63, had been taking high doses of six different blood pressure drugs daily for nearly ten years – yet even on this regime his blood pressured remained exceptionally high, hovering around 180/120.

‘My father and grandfather had both died young from heart attacks – at 62 and 71 respectively – and I was worried that would be my fate too. When I realised a stroke was even more likely that terrified me far more,’ Charles says.

‘My GP had been trying everything she could to lower my blood pressure but eventually offered a referral to a cardiologist. By luck, the one with the first appointment was at Addenbrookes, where I was invited to join a British Heart Foundation funded trial for patients with resistant hypertension, under Professor Brown who early on told me he suspected my hypertension was hormonal.’

With no detectable tumours, Charles did not qualify for surgery, but a combination of the drugs eplerenone and amiloride (a potassium sparing diuretic) now keeps his blood pressure at a steady 135/90.

Professor Brown says: ‘Stroke causes 42,000 deaths in the UK every year, but, with systolic blood pressure over 170-180, the risk overtakes that of heart attack – which kills 103,000 people annually.

‘We owe it to patients to make sure that their unexplained hypertension is investigated. This is why I am so keen for a blood test for renin to become routine in all younger patients, who might be prevented by surgery from developing resistant hypertension like Charles, or from needing any drug treatment at all.

‘Once resistant hypertension has developed, the chances of this being due to hyperaldosteronism are so high that, once again, renin should be measured, if only to make sure the patient receives the correct drugs which are not usually used in hypertension. Even in resistant hypertensives in whom hyperaldocteronism or Conn’s disease is not diagnosed, the rennin measurement will enable doctors to prescribe the most appropriate drug to successfully lower their blood pressure.

‘Not only is high blood pressure a major health risk, but the low levels of potassium hyperaldosteronism causes can be very fatiguing – our muscles need this mineral to perform at their peak. As soon as we redress this balance – with surgery or aldosterone blocking drugs – potassium levels return to normal, and patients often feel so much more energetic.

‘One patient even said her husband found her so energetic after surgery that he wished she could go back to how she had been before her Conn’s tumour was found and removed!’