Case study: An unusual case of uncontrollable BP

A regular check-up revealed an unexpected condition. By Dr Honor Merriman

Only a few patients have that calm and cheerful air that makes me look forward to seeing their name on my appointments screen. Justin is in his mid-fifties and is one such patient. One day he came to see me to request I take his BP.  

He had been prescribed bendroflumethiazide 2.5mg two weeks ago by another GP and wanted to know if it worked.  

Looking at a BP reading of 197/105mmHg — the best of three taken in silence with the patient’s eyes closed remembering his last holiday — I knew his treatment needed to be improved.  

He seemed very calm and accepted a prescription for an ACE inhibitor. He also agreed to read through a lifestyle advice leaflet, although as a cyclist, life-long non-smoker and one sherry at Christmas, lifestyle changes did not seem likely to make a big difference.  

Trying combinations  

Over the next few weeks we tried A, B, C and D in combination and then all of them together (the latest NICE guidelines were not then published). I checked that he was actually taking the tablets prescribed. He said that he had, and I believed him.  

I suddenly realised that nobody had checked renal function and electrolytes before starting treatment. I took blood for this, and for plasma lipids and glucose followed by organising an ECG.  

All the results came back as normal except for potassium of 2.5mmol/l.  

His BP readings were still very high. He was not taking any medication other than his anti-hypertensives. Readings were the same on each arm.  

I remembered coarctation as a possible cause of hypertension. I stopped his bendroflumethiazide and decided that it was time to ask the opinion of an expert, I was glad that he was unperturbed that his GP did not know how best to treat him.  

Before seeing him, the specialist wrote to me and suggested that I take blood for renin and aldosterone levels because she suspected Conn’s syndrome.  

She was correct, the aldosterone was high and the renin low. This suggested primary hyperaldosteronism.  

The patient then had a CT scan which confirmed the presence of a left sided adrenal adenoma.  

The surgeon decided to remove this laparoscopically, which was done as a day-case procedure. The patient made a rapid recovery and his BP returned to normal. A happy outcome for this patient.  

Conn’s syndrome  

Conn’s syndrome is said to account for 1 per cent of cases of hypertension, yet in our practice of 12,000 patients we have detected it in only two patients currently being treated for hypertension.  

Check that initial investigations and a cardiovascular risk assessment have been undertaken when reviewing a patient already started on medication for hypertension. This offers the best opportunity to detect secondary causes of hypertension. It may also allow patients to follow their progress in cardiovascular risk reduction as the BP comes under control.  

Use patient reviews to combine patient education (their needs) with the use of chronic disease templates (our needs). I found that I needed to update my patient information leaflets about lifestyle changes needed for patients with hypertension.  

Dr Merriman is a GP in Oxford  

Routine tests  

Necessary before starting treatment for hypertension: 

Urine: test for protein and blood (pointers to a renal cause for hypertension).  

Blood: electrolytes and renal function, fasting glucose, lipid profile (total cholesterol, LDL, HDL, triglycerides).  

ECG: to detect left ventricular hypertrophy and/or IHD.  

Secondary causes of hypertension  

Excessive alcohol intake  


Combined oral contraceptive pill.  



Sympathomimetics, for example in OTC cold remedies.  

Liquorice, for example in herbal medicines and in indigestion remedies.  

Cocaine and other substances of abuse.  

Renal disease  

Chronic pyelonephritis.  

Diabetic renal disease.  


Polycystic kidney disease.  

Obstructive uropathy.  

Renal cell carcinoma.  

Renal artery stenosis. 

Coarctation of the aorta  


Primary hyperaldosteronism (Conn’s syndrome).  


Cushing’s syndrome.

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