Liping Huang1,2, Mark Woodward2,3,4, Sandrine Stepien2, Maoyi Tian2,5, Xuejun Yin5,6, Zhixin Hao5, Zhifang Li7, Jixin Sun8, Yan Yu9, Bo Zhou10, Yi Zhao11, Yangfeng Wu5,12, Bruce Neal1,2,13,14. 1. The University of Sydney, Sydney, Australia. 2. The George Institute for Global Health, University of New South Wales, Sydney, Australia. 3. The George Institute for Global Health, University of Oxford, Oxford, UK. 4. Department of Epidemiology, Johns Hopkins University, Baltimore, MD, USA. 5. The George Institute for Global Health at Peking University Health Science Center. 6. Beijing University of Chinese Medicine. 7. Changzhi Medical College, Shanxi, China. 8. Center for Disease Control of Heibei, Hebei, China. 9. Xi'an Jiaotong University School of Medicine, Shaanxi, China. 10. First Hospital of China Medical University, Liaoning, China. 11. Ningxia Medical University, Ningxia Hui Autonomous Region, China. 12. Peking University Clinical Research Institute, Beijing, China. 13. Department of Medicine, Royal Prince Alfred Hospital. 14. Department of Epidemiology and Biostatistics, School of Public Health, Faculty of Medicine, Imperial College London, London, UK.
Abstract
Background: The capacity of spot urine samples for detecting changes in population sodium and potassium excretion is unclear. Methods: Changes in urinary sodium and potassium excretion, over a 6-month to 2-year interval, were measured from 24-h urine samples and estimated from spot urine samples using several published methods in 3270 Chinese. Additional estimates were made by multiplying individual spot sodium and potassium concentrations by a single estimated 24-h urine volume derived from external data. Results: The measured difference in 24-h urinary excretion between intervention and control groups was -0.35 g (95% CI: -0.68 to -0.02; P = 0.039) for sodium and 0.66 g (95% CI: 0.52 to 0.80; P < 0.001) for potassium, based upon 24-h urine samples. The corresponding estimates of sodium differences for the Tanaka (-0.06 g), Kawasaki (-0.09 g), Intersalt without potassium (-0.09 g) and Intersalt with potassium (-0.14 g) equations were all smaller and identified no reduction in sodium excretion (all P > 0.10). The estimates were -0.65 g for sodium and 1.11 g for potassium using individual spot urine concentrations and an externally derived standard urine volume (both P < 0.01). Conclusions: The published equations were unable to detect the differences in sodium excretion measured by 24-h urine samples. A method based upon spot urine electrolyte concentrations and a standard urine volume may offer an alternative approach to measuring differences in sodium and potassium excretion between population groups without requiring 24-h urine, but will need further investigation.
RCT Entities:
Background: The capacity of spot urine samples for detecting changes in population sodium and potassium excretion is unclear. Methods: Changes in urinary sodium and potassium excretion, over a 6-month to 2-year interval, were measured from 24-h urine samples and estimated from spot urine samples using several published methods in 3270 Chinese. Additional estimates were made by multiplying individual spot sodium and potassium concentrations by a single estimated 24-h urine volume derived from external data. Results: The measured difference in 24-h urinary excretion between intervention and control groups was -0.35 g (95% CI: -0.68 to -0.02; P = 0.039) for sodium and 0.66 g (95% CI: 0.52 to 0.80; P < 0.001) for potassium, based upon 24-h urine samples. The corresponding estimates of sodium differences for the Tanaka (-0.06 g), Kawasaki (-0.09 g), Intersalt without potassium (-0.09 g) and Intersalt with potassium (-0.14 g) equations were all smaller and identified no reduction in sodium excretion (all P > 0.10). The estimates were -0.65 g for sodium and 1.11 g for potassium using individual spot urine concentrations and an externally derived standard urine volume (both P < 0.01). Conclusions: The published equations were unable to detect the differences in sodium excretion measured by 24-h urine samples. A method based upon spot urine electrolyte concentrations and a standard urine volume may offer an alternative approach to measuring differences in sodium and potassium excretion between population groups without requiring 24-h urine, but will need further investigation.
Authors: Eoin Morrissey; Miriam Giltinan; Laura Kehoe; Anne P Nugent; Breige A McNulty; Albert Flynn; Janette Walton Journal: Nutrients Date: 2020-03-28 Impact factor: 5.717