Effectiveness of a Self-monitoring Device for Urinary Sodium-to-Potassium Ratio on Dietary Improvement in Free-Living Adults: a Randomized Controlled Trial

Abstract

BackgroundReducing the urinary sodium-to-potassium ratio is important for reducing both blood pressure and risk of cardiovascular disease. Among free-living Japanese individuals, we carried out a randomized trial to clarify the effect of lifestyle modification for lowering urinary sodium-to-potassium ratio using a self-monitoring device.MethodsThis was an open, prospective, parallel randomized, controlled trial. Ninety-two individuals were recruited from Japanese volunteers. Participants were randomly allocated into intervention and control groups. A month-long dietary intervention on self-monitoring urinary sodium-to-potassium ratio was carried out using monitors (HEU-001F, OMRON Healthcare Co., Ltd., Kyoto, Japan). All participants had brief dietary education and received a leaflet as usual care. Monitors were handed out to the intervention group, but not to the control group. The intervention group was asked to measure at least one spot urine sodium-to-potassium ratio daily, and advised to lower their sodium-to-potassium ratio toward the target of less than 1. Outcomes included changes in 24-hour urinary sodium-to-potassium ratio, sodium excretion, potassium excretion, blood pressure, and body weight in both groups.ResultsMean measurement frequency of monitoring was 2.8 times/day during the intervention. Changes in urinary sodium-to-potassium ratio were −0.55 in the intervention group and −0.06 in the control group (P = 0.088); respective sodium excretion changes were −18.5 mmol/24 hours and −8.7 mmol/24 hours (P = 0.528); and corresponding potassium excretion was 2.6 mmol/24 hours and −1.5 mmol/24 hours (P = 0.300). No significant reductions were observed in either blood pressure or body weight after the intervention.ConclusionsProviding the device to self-monitor a sodium-to-potassium ratio did not achieve the targeted reduction of the ratio in “pure self-management” settings, indicating further needs to study an effective method to enhance the synergetic effect of dietary programs and self-monitoring practice to achieve the reduction. However, we cannot deny the possibility of reducing sodium-to-potassium ratio using a self-monitoring device.

Assessment and validation of spot urine in estimating the 24-h urinary sodium, potassium, and sodium/potassium ratio in Chinese adults

“…Base on the previous studies, a urinary Na/K molar ratio of 1.0 may be a target level [14]. Measurement of the casual urine Na/K ratio also has the potential for providing prompt feedback to individuals using a selfmonitoring device [32]. However, it seemed difficult for Chinese participants to achieve the target level of Na/K ratio recommended.…”

Time to Consider Use of the Sodium-to-Potassium Ratio for Practical Sodium Reduction and Potassium Increase

“…This device measures urinary Na/K ratio by the ion electrode method and displays the result within one minute. Since this device provides prompt onsite feedback in personal use, it became evaluated in randomized control trial with a view to support an individual approach for Na reduction and K increase [ 72 ]. With regard to the individual approach, it is important that there is a balance between lower effort and financial burden in order to achieve an effective intervention.…”

“…A recent study that examined this self-monitoring device reported finding a trend for larger reductions in the urinary Na/K ratio in a self-monitoring group under a pure self-management setting. When the baseline urinary Na/K molar ratio level was approximately 3.7, the reductions in the urinary Na/K molar ratio were 0.55 in the intervention group and 0.06 in the control group [ 72 ]. However, the intervention effect size was limited due to the lack of an effective education program for reducing the Na/K ratio.…”

Urinary Sodium-to-Potassium Ratio Tracks the Changes in Salt Intake during an Experimental Feeding Study Using Standardized Low-Salt and High-Salt Meals among Healthy Japanese Volunteers

“…Epidemiological studies have suggested that the urinary Na/K ratio is a better measurement of dietary Na reduction and K increase in relation to BP and CVD risk assessments than separate Na or K levels [ 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. Additionally, the former is easier to measure than the latter, due to its independence from urine collection and creatinine measurement; indeed, repeated Na/K ratio measurements from spot urine samples provide more reliable estimates than those from 24-h urine samples [ 28 , 29 , 30 ]. Previous studies have demonstrated that single spot urine samples can be used to estimate the population mean values of the 24-h urine Na/K ratio [ 28 ], and that four to seven repeated measurements of the Na/K ratio in spot urine samples can be used to estimate the 24-h urine Na/K ratio in individuals [ 29 , 30 ].…”