kidney failure and diuretics

[Pharmguru]

Why are diuretics not used/stopped in kidney failure. When you have a heart failure patient your kindeys don't work as well but you still use them to get rid of fluid.
In kidney failure, you will have same problem with fluid overload so wouldn't diuretics be a good choice.

[Nik]

First things first - diuretics, as well as many other drugs, can be nephrotoxic. Furosemide can cause pre-renal ARF through hypovolaemia, and it's also been implicated in intrinsic renal toxicity by causing acute tubular necrosis (ATN). Thiazides are ineffective once GFR drops below 30ml/min. Signs of fluid overload can be a late presentation but if loop diuretics are still needed, then higher doses need to be prescribed. (NB fluid overload can be due to excessive use of IV fluids).
In patients with pre-renal ARF (ie due to hypovolaemia) they will get IV fluids as first line, usually 0.9% saline. If patients progress from ARF to ATN, then they may get given massive doses of loops, typically 250-500mg furosemide. The theory behind it is that loops have been shown to increase renal blood flow but there's no evidence that they actually reduce mortality or the time to dialysis.

[Pharmguru]

so is it more thiazides we look to avoid in renal failure

[Nik]

You have to take care with all diuretics in renal impairment generally...

[johnep]

I believe bumetanide may be better tolerated.
johnep

[Pharmguru]

how does this relate to heart failure fluid overload? kidneys don't work well in hf either do they.

[Nik]

Diuretic use in heart failure is different to diuretic use in renal failure. In patients who have both, the use of diuretics then becomes a balancing act to ensure symptoms of fluid overload are treated without adversely affecting renal function.

[laurabuk]

Nik, have you ever seen frusemide doses that high in practice? think the most I've seen is 80mg BD?

(PS you've out-geeked me again!)

[Nik]

The most I've seen is 250mg IV od - no ceiling effect with loops so can give more and more. Torasemide and bumetanide don't tend to get used. Nurses understandably are scared of these doses as well as pharmacists. !

[johnep]

One point may be relevant. If pt has gut oedema, than Frusemide poorly absorbed. Bumetanide absorbed better under these conditions. However, because of this, if patient given Bumetanide at 1;40 of Frusemide dose, may sludge. Best to start with no more than 5mg and titrate upwards.
johnep