Laboratory medicine in primary care Monitoring renal function in hypertension
Several classes of antihypertensive drugs can cause a fall in glomerular filtration rate and a rise in serum potassium and creatinine concentrations. Una Martin and Jamie J Coleman discuss the implications
We present two typical cases seen in a hospital hypertension clinic that illustrate the role of measurement of electrolytes and renal function in patients treated with angiotensin inhibitors (angiotensin converting enzyme (ACE) inhibitors and angiotensin II receptor antagonists) or potassium sparing diuretics.
Both cases highlight the need to identify patients at increased risk of developing difficulties when taking such antihypertensive drugs and the need to target increased monitoring in at-risk patients.
A 64 year old woman was referred to a hypertension clinic with a blood pressure of 180/110 mm Hg. Her biochemical profile was normal (serum creatinine concentration 102 µmol/l, urea 6.4 mmol/l, potassium 4.2 mmol/l, sodium 139 mmol/l). Treatment started with amlodipine 5 mg, and when she was reviewed, six weeks later, her blood pressure was 165/95 mm Hg. Perindopril 4 mg was added, and one week later her blood pressure was 144/70 mm Hg. However, her renal function