Few days ago during a night shift, I saw an elderly gentleman from the nursing home who had a potassium of 6.9 mEq/L, among other lab abnormalities. His EKG had some tall T waves, but otherwise, he was asymptomatic. We proceeded to do the usual stuff; calcium, insulin, glucose, albuterol, IVF and some furosemide. We called for a monitored bed and when the patient went up, shortly after I got a call from the floor nurse asking why we didn't give Kayexalate to the hyperkalemic patient. I saw this as an opportunity to educate about how uneffective Kayexalate is and the possible risks of using this ancient and mostly unproven therapy, so I gladly explained that to the nurse. Few minutes later I got a phone call from the hospitalist asking the same question, "why didn't you give Kayexalate to the hyperkalemic patient?" - Now I am thinking... The nurse not only didn't believe me, she called the hospitalist at 3 am to tell him about my terrible omission of therapy! Once again, I tried to explain my reasons for not giving the resin. Dr X, an internist, proceeded to give me a physiology lecture about potassium metabolism and elimination. I politely listened, thanked him for his time and at the end told him that he may want to read what the nephrology literature says about this topic.
I really thought this Kayexalate issue had been put to rest few years ago. Why are we so hard to break old habits? This wouldn't be the first time; after all, medical science has had many bloopers when it comes to therapies, things we thought were good for our patients that were later proven to cause harm. Remember Thalidomide, HRT, Xigris..? It is wise to keep an open mind and look for the evidence behind our practice. So, let's see what the literature says about Kayexalate.
Sodium polystyrene sulfonate, AKA Kayexalate, made its debut in 1957 for the treatment of hyperkalemia. This resin was initially used alone but it caused severe constipation and colonic necrosis, then sorbitol was added as a cathartic. Although less frequent, the combination still has reports of colonic necrosis, perforation and poor outcomes related to its use. That's the reason why in 2009 the FDA issued a black box warning for Kayexalate. I bet you didn't see that one coming, did you? But does it work to reduce potassium? The short answer is NOT really. However, I will go over the long answer. There are only 3 paper in the literature that support the use of Kayexalate: 1) Flinn RB et al. Treatment of the oliguric patient with a new sodium-exchange resin and sorbitol; a preliminary report. N Engl J Med. 1961 Jan 19;264:111-5. This included 10 patients who received potassium free diet + resin/sorbitol. The potassium decreased 0.5 mEq in 24 hrs, and no control group. 2) Scherr L et al. Management of hyperkalemia with a cation-exchange resin. N Engl J Med. 1961 Jan 19;264:115-9. This one had 32 patients with renal failure, all received potassium free diet and Kayexalate oral or rectally. The average reduction in serum potassium was 1 mEq in 24 hr. Again, no control group. 3) Gruy-Kapral C et al. Effect of single dose resin-cathartic therapy on serum potassium concentration in patients with end-stage renal disease. J Am Soc Nephrol. 1998 Oct;9(10):1924-30. This one took 6 patient with renal failure and found no change in serum potassium levels at 12 hrs, and not surprising, this one had no control group either. Although this last study could be seen as a negative study, it is frequently cited as a reason to use the resin. But that's it…! The evidence to support the use of Kayexalate is based in 3 poorly done studies, with the grand total of 48 patients and no control group in any of them. Really… that's it!
And now for the grand finale…. In 2010 the nephrologists digged deep into this literature, which wasn't that hard b/c there is no much of it, and came to the same conclusion published in this paper: Sterns RH et al. Ion-exchange resins for the treatment of hyperkalemia: are they safe and effective? J Am Soc Nephrol. 2010 May;21(5):733-5. (http://www.ncbi.nlm.nih.gov/pubmed/20167700 and http://jasn.asnjournals.org/content/early/2010/02/18/ASN.2010010079.abstract) If kayexalate and sorbitol were presented to the FDA today, they would likely not be approved. “It would be wise to exhaust other alternatives for managing hyperkalemia before turning to these largely unproven and potentially harmful therapies".
There you have it… From the Nephrologist's mouth; another myth debunked. Please please pleeeeeease…. forward this post to all your colleagues, and once you are at it, send it to your grandparents, soccer team and the neighbors. It is time to stop using this therapy and get on board with the current times.
Really... A Kayexalate coupon?!
Even the cartoons need to change!
In a side note: Thank you to all my friends at VBMC for treating me so well, to the folks in King Faisal University Hospital for putting such a great conference and letting me be part of it and to my buddies in London for making it my second home. You all know who you are...