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Re: Authors' reply

Dear Editor,

We are grateful to Dr. Exton for allowing us to expand on the case we reported recently [1]. Our patient’s past history of widespread vascular disease included previous MI, CABG and heart failure which is why her therapy included enalapril 5 mg b.d., Bumetanide 2 mg od, and Bisoporolol 5 mg od. We were not unduly alarmed therefore to find that her urea had been elevated at 15.3 mmol/l with serum creatinine 135 umol/l three weeks before admission. A degree of renal impairment has always been an acceptable compromise, in our view, for keeping the lungs free of fluid in patients with heart failure, and is anyway a normal haemodynamic response to ACE inhibition. While we would fully accept that salt and water depletion from any cause can lead to acute renal failure, we are struggling to believe as Dr. Exton may be implying, that the Bumetanide was in any way inappropriate in this patient’s case, or that it was the main reason why she developed acute renal failure with life threatening hyperkalaemia. Our patient continues to do well, incidentally, with blood pressure 124/73 mm Hg, serum potassium 4.6 mmol/l, blood urea 9.7 mmol/l and serum creatinine 115 umol/l 2 years after her presentation with acute renal failure, while taking exactly the same medication as before.

Chris Isles
Sue Robertson

Reference

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Re: Diuretic induced renal failure

Dear Editor,

Clearly the ACE inhibitor in this case is significant in light of this lady's acute (presumably mixed "pre-renal" and "renal") renal failure. However, this was not due solely to one drug and I suspect that her illness highlights a more significant problem i.e. that of the widespread use of loop diuretics and the balance between fluid offload and renal function. Although the precise nature of her vasculopathy and rest of her medical history is not given I would suggest that this is the least appropriate of her medication - unless good evidence existed of poor LV function etc. Her electrolytes three weeks prior were not normal and I would have thought that diuretic therapy at that stage should have been reviewed or her electrolytes repeated sooner. Diuretic induced renal failure - or at least "renal impairment" - is much more frequent in acute admissions than once per month. Furthermore, they are often prescribed to patients who seem neither to have significant relevant symptomatology or appropriate monitoring in place.