Effects of Short-Term Potassium Chloride Supplementation in Patients with Chronic Kidney Disease

Background: Observational studies suggest that adequate dietary potassium intake (90-120 mmol/day) may be renoprotective, but the effects of increasing dietary potassium and the risk of hyperkalemia are unknown. Methods: This is a pre-specified analysis of the run-in phase of a clinical trial in which 191 patients (age 68 ± 11 years, 74% males, 86% European ancestry, eGFR 31 ± 9 mL/min/1.73 m², 83% renin-angiotensin system inhibitors, 38% diabetes) were treated with 40 mmol KCl/day for two weeks. Results: KCl supplementation significantly increased urinary potassium excretion (72 ± 24 to 107 ± 29 mmol/day), plasma potassium (4.3 ± 0.5 to 4.7 ± 0.6 mmol/L), and plasma aldosterone (281 [198-431] to 351 [241-494] ng/L), but had no significant effect on urinary sodium excretion, plasma renin, blood pressure, eGFR, or albuminuria. Furthermore, KCl supplementation increased plasma chloride (104 ± 3 to 105 ± 4 mmol/L), reduced plasma bicarbonate (24.5 ± 3.4 to 23.7 ± 3.5 mmol/L) and urine pH (all P < 0.001), but did not change urinary ammonium excretion. Twenty-one participants (11%) developed hyperkalemia (plasma potassium 5.9 ± 0.4 mmol/L). They were older and had higher baseline plasma potassium. Conclusions: In patients with CKD stage G3b-4, increasing dietary potassium intake to recommended levels with potassium chloride supplementation raises plasma potassium by 0.4 mmol/L. This may result in hyperkalemia in older patients or those with higher baseline plasma potassium. Longer-term studies should address whether cardiorenal protection outweighs the risk of hyperkalemia.