Hyperkalemia, defined as a serum potassium level above 5.3 mmol/L, develops in many patients with chronic kidney disease (CKD). The abnormality can precipitate serious adverse outcomes, including dysrhythmias and sudden cardiac death, so patients with elevated blood potassium levels may be referred to emergency departments or urgent care facilities for immediate therapy. As a result, nephrologists and dietitians universally instruct CKD patients to avoid foods rich in potassium. These include fresh fruits and vegetables with high fiber content. Consequently, CKD patients may not be getting enough dietary fiber, potentially resulting in constipation and other problems. The Recommended Dietary Allowance for total dietary fiber should reach 30 grams a day from natural foods. Currently, dietary fiber intake among adults in the United States is about 15 grams a day, and the intake is even lower in CKD patients, given the imposed dietary potassium restriction.
This presents nephrologists with a conundrum. They universally prescribe ACE inhibitors and angiotensin receptor blockers (ARBs) to CKD patients in an attempt to slow kidney disease progression or mitigate proteinuria. These medications, however, are notorious for causing or aggravating hyperkalemia. So nephrologists not infrequently withhold ACE inhibitors and ARBs from patients who experience hyperkalemic episodes or acute kidney injury (AKI) events. But there may be alternative treatments for which dietary potassium restrictions aimed at preventing hyperkalemia may be unnecessary.
Recently, emerging data suggest that additional groups of medications may be effective in slowing CKD progression. These include SGLT2 inhibitors, such as canagliflozin, dapagliflozin, and empagliflozin. Studies such as EMPAREG, CREATE, and CREDENCE have shown promising results regarding the use of SGLT2 inhibitors to manage CKD. Similar data exist for other classes of medications, including the endothelin antagonist atrasentan, as well as the NRF2 modulator bardoxolone and the epigenetic modulator apabetalone.
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With new classes of agents offering the promise of therapeutic alternatives to the use of ACE inhibitors and ARBs in CKD patients, we may be able to stop or at least relax restrictions on dietary potassium intake. Meanwhile, the use of potassium binding agents for hyperkalemia control may also allow for more consumption of heart-healthy diets with less risk of hyperkalemia. We may be on the cusp of a new era in which we can encourage CKD patients to increase their dietary intake of fresh fruits and vegetables.
