Dietary potassium is not a major contributor to elevated serum potassium levels and hyperkalemia in patients with chronic kidney disease (CKD), new study findings suggest.
Shigeru Nakai, MD, PhD, of Fujita Health University School of Health Sciences in Aichi, Japan, and colleagues studied the association between 24-hour urinary potassium excretion, an indicator of daily dietary potassium intake and serum potassium in patients with CKD stages G3 to G5 who participated in the Multiple 24-hour Urine Collection Study. A total of 290 Japanese patients provided 3 urinary collections each for a total of 870 observations (3 times cohort). A subset of 220 Japanese patients provided 7 urinary collections each for a total of 1540 observations (7 times cohort).
In the 3 times cohort, serum potassium increased by a mean 0.12 mEq/L for every 10 mEq per day increase in 24-hour urinary potassium excretion, the investigators reported in Kidney International Reports. Advancing CKD stage was associated with worse results. Serum potassium increased 0.08, 0.12, and 0.16 mEq/L for every 10 mEq per day increase in 24-hour urinary potassium excretion at CKD stages 3, 4, and 5, respectively.
The odds of hyperkalemia significantly increased 2.1-fold per 10 mEq per day increase in 24-hour urinary potassium excretion, Dr Nakai and colleagues reported.
The investigators adjusted the 3 times cohort analysis for comorbidities such as diabetes and hypertension. They also adjusted for medications that could increase or decrease serum potassium levels. Medications that increase serum potassium included angiotensin-converting enzyme inhibitors (ACE inhibitors), angiotensin II receptor blockers, mineralocorticoid receptor antagonists, renin inhibitors, and potassium supplements. Medications that decrease serum potassium included diuretics, sodium-glucose cotransporter-2 inhibitors, potassium binder, licorice extract, and bicarbonate.
An analysis of the 7 times cohort yielded similar results.
Dr Nakai’s team highlighted that their findings are insufficient to support or oppose any dietary approaches to hyperkalemia. Besides nutrient intake from foods, urinary excretion of potassium also reflects transcellular shifts in potassium and potassium changes from medication use.
The study lacked specific dietary information, such as potassium additives in foods and plant intake, and relevant conditions affecting serum potassium, such as metabolic acidosis, constipation, and hyperglycemia.
In an accompanying editorial, Shivam Joshi, MD, of the Department of Veterans Affairs in Orlando, Florida, and colleagues noted that the study adds to “a growing body of evidence that suggests a weak association of dietary potassium with serum potassium.” “Further research is, of course, needed to answer ongoing questions regarding the applicability of potassium-rich diets in patients with kidney disease,” they wrote.
A separate study published in Nephrology Dialysis Transplantation found that the 5 variables most associated with hyperkalemia were estimated glomerular filtration rate, original nephropathy, age, diabetes, and plasma bicarbonate level. “The results of this study do not support a strict dietary potassium control to regulate kalemia in stage 1 to 4 CKD patients,” Maelys Granal, MD, of Lyon University, in Lyon, France, and colleagues concluded.
Disclosure: The research by Dr Nakai’s team was supported by HU Group Holdings. Please see the original reference for a full list of disclosures.
Ogata S, Akashi Y, Kato S, et al. Association between dietary potassium intake estimated from multiple 24-hour urine collections and serum potassium. Kidney Int Rep. Published online December 11, 2022. doi:10.1026/j.ekir.2022.12.005
Joshi S, Babich JS, Shen J, Kalantar-Zadeh K. Piecing together the potassium puzzle: The weak association between dietary potassium and hyperkalemia. Kidney Int Rep. Published online February 2, 2023. doi:10.1016/j.ekir.2023.01.028
Granal M, Fouque D, Ducher M, Fauvel JP. Factors associated with kalemia in renal disease in patients with CKD. Nephrol Dial Transplant. Published online January 20, 2023. doi:10.1093/ndt/gfad015