Low potassium diet

Leamington Spa, May 2012

My thanks to readers who went to the lengths of Googling following my last post, to reveal that SOL in the context of a head scan stands for Space Occupying Lesion (i.e. probable tumour or perhaps a bleed). I somehow don't trust Google to come up with accurate medical abbreviations, but in this case it seems plausible. And nice to know that people other than my immediate family are still reading. My stats last week show 80 unique visitors to this blog, while the previous (now defunct) blog still received 76 unique visitors in the same week. The difference is that the new blog had 55 returning visitors last week, while the old only has 5.

Further feedback from last time asked why I wasn't willing to provide information about a low potassium diet to a patient. This case led to the first proper contact I'd had with the renal Dietitians, who inhabit an adjacent room in the department. The hospital has a large specialist renal unit and is some sort of centre of excellence for kidney disease, so we have quite a few renal Dietitians. Sometimes I bump into them on my wards, if one of their patients develops a condition alongside their renal impairment, and is put in a bed somewhere other than the renal wards.

So here's the scenario: a patient on one of my wards has a raised blood potassium level (which may be harmful if it continues), and one of the doctors asks me to give the patient some advice on following a low potassium diet. They insist it is not a renal patient, otherwise I would have handed it over to a renal Dietitian straight away. But putting someone on a low potassium diet who isn't a renal patient is somewhat unusual to say the least, and one of the threads running through everything we do as Dietitians is to avoid unnecessary dietary restrictions that could put an individual at risk of a dietary deficiency. It might also alarm, confuse or distress them without commensurate benefit to their health.

Add to that uncertainty the fact that giving advice on a low potassium diet is something the renal Dietitians do all the time and I've never needed to do so far, so I needed to read up a bit on what's required and find the most appropriate information sheet from the files. Because we've got a whole load of renal Dietitians sitting in the next room, it made sense to ask them for advice on what I should do.

At this point, to their credit, they didn't just answer my questions, but asked a whole lot more of their own. What is the current potassium level, and what has the trend been in the past? What are the other U+E's like (blood urea and electrolytes), including creatinine (which can give an indication of the level of renal impairment)? What is the main presenting complaint? Is the patient diabetic, and if so, what is their blood sugar control like? What medications are being given, and have any been changed?

Of course I don't know the answers to any of these questions. All I'd been asked to do is provide information on a low potassium diet for someone who isn't a renal patient. So at this point, I started to learn a whole lot of new stuff about potassium metabolism and renal function.

We looked up the trends of blood results on the computer system, and the renal Dietitian pointed out the trends of high creatinine at certain points linked with higher potassium results, suggesting that these indicate times of acute kidney injury, plus the ratio to blood urea showed something else that I can't quite remember. Since the referral, recorded potassium levels had returned to the high end of the 'normal' range. The patient is diabetic, and blood sugar results were higher than one would wish. Insulin also helps to remove potassium from the bloodstream along with glucose, so poorly controlled diabetes will often mean higher levels of blood potassium. The renal Dietitian did a quick calculation that suggested that the patient's estimated kidney function was not impaired to a degree that would require dietary restriction.

I headed up to the ward armed with this information. I was still blindly following orders, and reviewing the medical notes I looked for specific medications that the renal Dietitian suggested might be there. There were also other features in the notes that I can't write about here, all of which suggested that limiting dietary potassium was actually not going to make a whole lot of difference. So I bleeped the doctor to try and discuss the case, but was told in no uncertain terms that I had been asked to provide advice on a low potassium diet, and they would be very grateful if I would do just that.

So I called in the cavalry, and the renal Dietitian came up to the ward, went through all the information we had gathered, and wrote her assessment in the medical notes, concluding that because the high potassium was not caused by dietary intake (and bearing in mind several other documented factors), it did not seem appropriate to offer dietary advice, and the medical steps being taken seemed to be working anyway. It was a masterly summary, which I hoped to copy along with lots of other information so I can document the technicalities of renal Dietetics that I've learned from this case, and add it to my CPD portfolio. But the patient has already been discharged, and I've no idea where the notes go when that happens.