#118: Even MORE Bananas, B-A-N-A-N-A-S: Hyperkalemia in CKD

August 21, 2024 | By Sam Masur

Audio

Summary:

In our last episode, we discussed hyperkalemia management in an otherwise renally healthy patient. But what if your patient has chronic kidney disease? Are they okay if their potassium has been 5.9 for a long time? How does our management change? Nephrologist Dr. Jordan Symons returns to offer his advice on outpatient and inpatient management of acute-on-chronic hyperkalemia.

Acute-on-Chronic Hyperkalemia Pearls

1. Patients with CKD may have chronic elevations of potassium – if their trend is stable, they likely have a lower risk of arrhythmias on presentation.
2. Dr. Symons generally finds K < 6 acceptable in stable CKD patients. Stability is defined over months – not weeks or years
3. Outpatient management of hyperkalemia consists of dietary counseling and medication adjustment.
4. There is no standard IV fluid or formula for a patient with CKD. Dr. Symons always recommends treating the patient in front of you. 

Hyperkalemia Part 2: Notes

In this brief add-on episode, we’ll discuss the management of hyperkalemia in a patient with chronic kidney disease. 

As a refresher (find more in the show notes for hyperkalemia part 1), potassium is essential for maintaining a resting cell potential, especially in the heart. Normal levels range from 3.5-5.5 meQ/mL. The most dangerous consequence of hyperkalemia is cardiac arrhythmias and arrest.

In a patient with chronic kidney disease, long term elevations of potassium are almost always related to problems with excretion, due to: low GFR, tubular dysfunction, distal secretion issues, or iatrogenic (potassium sparing diuretics, ACE inhibitors, calcineurin inhibitors, all of which are more likely to be prescribed medications in CKD).

Expert pearl: Every doubling of the serum creatinine means the GFR is cut in half, which can negatively affect secretion of many substances and electrolytes.

Expert opinion: many of the CKD patients are in the high 5s already for their potassium. It is important, then, to look at a patient’s potassium trends over time, and there is even a possibility of sending home for outpatient follow-up. 

Expert practice: Potassium <6 is generally acceptable; potassium >6 warrants a closer look at context, such as recent changes in medication or diet.

Chronic hyperkalemia over time (approx 3-6 months according to our expert) is a bit safer because the cell membranes acclimate to higher levels of potassium. An exception is a patient who is also hypocalcemic, which will perturb the calcium:potassium ratio putting the patient at higher risk of cardiac arrhythmias. 

The outpatient management of hyperkalemia consists of:

• Nutrition: Patients must eat a special renal diet low in potassium, excluding foods like potatoes, soft drinks, and avocados (our expert recommends soaking potatoes to leech some potassium from it). For infants, breastmilk is low in potassium, as are some special formulas; one could consider mixing a regular formula with a potassium binder, although evidence is weak for this intervention. From an equity perspective, this can be quite difficult for patients whose families are experiencing food insecurity. 
• Medications: can add diuretics; balance anti-hypertensives; possibly decrease calcineurin inhibitors or switch to another class of immunosuppressants; add a potassium binder (although our expert warns that sodium polystyrene sulfonate tastes pretty bad). 
• Checking labs often: most CKD patients get routine labs. The lower the GFR, the sooner you might consider re-checking labs after a medication adjustment.
• Dialysis: an intervention as the next line if all the other interventions fail. Usually, a discussion about discussing dialysis (unless emergent) is best left to the nephrologist who has a longitudinal relationship with the patient.

The management of hyperkalemia, if deemed acute, is much like the management for acute hyperkalemia in the non-CKD patient, with a few exceptions:

• There is no “standard” of rate or makeup of IV fluids, parenteral nutrition, etc. Our regular maintenance fluid calculators don’t work, nor do the typical recommendations of sodium/potassium additives into PN.
• If there is no nephrologist on-call, always err on the side of less – e.g. omit potassium from IVF
• If you have to administer an option that has more potassium (e.g. non-renal formulas), check labs more often.

Goal

Listeners will explain the differences in chronic management of hyperkalemia in a patient with chronic kidney disease, both in the outpatient and inpatient setting.

Learning Objectives

1. Be familiar with the general categories of causes of hyperkalemia in CKD.
2. Recognize the importance of a low-potassium diet and medication adjustments to best normalize potassium.
3. Feel comfortable with principles of managing hyperkalemia in CKD.

Disclosures

Dr Symons reports no relevant financial disclosures. The Cribsiders report no relevant financial disclosures. 

Citation

Zhang AY, Symons J, Masur S, Chiu C, Berk J. “#118: Even MORE Bananas, B-A-N-A-N-A-S: Hyperkalemia in CKD”. The Cribsiders Pediatric Podcast. https:/www.thecribsiders.com/ August 21, 2024.