Association of serum potassium level with dietary potassium intake in Chinese older adults: a multicentre, cross-sectional survey

OBJECTIVES: Evidence linking dietary potassium and serum potassium is virtually scarce and inconclusive. The aim of the study was to investigate the association between serum potassium level and potassium intake measured by 24-hour urine. We also explored whether the association differed across health conditions. DESIGN: A cross-sectional study conducted from September 2017 to March 2018. SETTING: 48 residential elderly care facilities in northern China. PARTICIPANTS: Participants aged 55 years and older and with both serum potassium and 24-hour urinary potassium measured were classified as having a low (apparently healthy), moderate (with ≥1 health condition but normal renal function) and high (with ≥1 health condition and abnormal renal function) risk of hyperkalaemia. EXPOSURE: Potassium intake is measured by 24-hour urinary potassium. OUTCOMES: Serum potassium in association with potassium intake after adjustment for age, sex, region and accounting for the cluster effect. RESULTS: Of 962 eligible participants (mean age 69.1 years, 86.8% men), 17.3% were at low risk, 48.4% at moderate risk and 34.3% at high risk of hyperkalaemia. Serum potassium was weakly associated with 24-hour urinary potassium among individuals with moderate (adjusted β=0.0040/L; p=0.017) and high (adjusted β=0.0078/L; p=0.003) but not low (adjusted β=0.0018/L; p=0.311) risk of hyperkalaemia. CONCLUSIONS: A weak association between dietary potassium intake and serum potassium level existed only among individuals with impaired renal function or other health conditions but not among apparently healthy individuals. The results imply that increasing dietary potassium intake may slightly increase the risk of hyperkalaemia but may also decrease the risk of hypokalaemia in unhealthy individuals, both of which have important health concerns. TRIAL REGISTRATION NUMBER: NCT03290716; Post-results.