Prevalence and correlates of hyperkalemia in a renal nutrition clinic

Hyperkalemia (HK) is a frequent complication of chronic kidney disease (CKD). Vegetable-based renal diets are considered at risk due to the high potassium (K) content. The aim of this study was to describe the prevalence and correlates of chronic hyperkalemia (HK) in CKD patients on nutritional care, and in particular, the risk of HK in patients on plant-based versus animal-based low-protein diets. We recruited adult patients affected by CKD not on dialysis, afferent to our renal nutrition clinic from November 2014 to May 2019. We evaluated a total of 870 accesses in 219 patients (172 m, 47 f, age 67 ± 13 years). HK was defined as mild when K serum level was 5.1-5.9 mEq/l, moderate when K serum level was 6.0-6.9 mEq/l, and severe HK when K serum level was ≥ 7 mEq/l. Biochemical, anthropometric data and medications were recorded. The prevalence of HK in all the renal nutrition visits was 26.1%; all but six cases were mild HK, whereas no severe HK was observed. The prevalence of HK was associated with decreased eGFR, up to 36.5% for eGFR < 20 ml/min. Medications were similar in hyperkalemic and normokalemic patients, RAASi being present in up to 85% of patients. In a follow-up of 40 ± 14 months, no association was found between HK and mortality, whereas HK, at the start of follow-up, showed a trend to increased ESRD risk. Serum potassium levels and prevalence of HK were not different between patients on animal-based low-protein diet and plant-based low-protein diet. In conclusion, chronic HK is quite prevalent in a renal nutrition clinic, especially when eGFR falls down below 60 ml/min, thereby reaching the highest prevalence in CKD stage 4. Hyperkalemia is mostly mild, being moderate to severe HK quite infrequent. Hyperkalemia was not associated with higher risk of mortality, whereas a trend, although not statistically significant, was observed for lower ESRD-free survival. Plant-based low-protein diet is not associated with significant higher prevalence of HK with respect to animal-based LPD at the same residual kidney function.