Awareness of salt restriction is not reflected in the actual salt intake in Japanese hypertensive patients

Abstract

Objectives: The Japanese guidelines for hypertension management recommend reducing salt intake to <6?g/day for hypertensive patients. However, it is not currently known whether hypertensive patients’ awareness of the recommended reduced salt diet correlates with their actual intake. Therefore, the purpose of this study was to investigate the relationship between actual salt intake of Japanese hypertensive patients and their awareness of the recommended guidelines for reduced dietary salt intake. Methods: In total, 236 outpatients (146 males and 90 females) with a mean age 69.7?±?12.5?years were included in this study. Daily dietary salt intake was estimated using sodium and creatinine concentrations detected in spot urine samples. The patients filled out a questionnaire regarding their awareness of recommended salt restriction for hypertension management. The questionnaire distinguished the patients’ awareness of recommended salt restriction in four levels (low, moderate, high and very high). Results: The mean estimated salt intake was 9.72?±?2.43?g/day. Patients’ awareness regarding salt intake in all levels provided in the questionnaire did not correlate with actual salt intake (p?=?0.731). Conclusion: Our results demonstrated that Japanese hypertensive outpatients consumed higher levels of salt than the target value recommended by Japanese guidelines. There was no correlation between actual salt intake and patients’ awareness of the recommended reduction in salt. These results suggest that monitoring salt intake and informing patients of their actual salt intake are necessary for effective hypertension management.     

Second morning urine method is superior to the casual urine method for estimating daily salt intake in patients with hypertension

The accuracy of the casual urine (CU) method for estimating daily salt intake was compared with the second morning urine (SMU) method and with 24-h urine collection (24 UC) method as the gold standard. Data were obtained from three previously reported studies, in which we evaluated the daily salt intake by the SMU method. Using SMU samples from 1315 outpatients, the estimated salt intake was lower with the CU method than the SMU method. In inpatients with a daily salt intake of 7, 8 or 18 g, the CU method was applied to SMU specimens. It underestimated salt intake compared with the 24-h collection method whereas the SMU method and 24 UC method gave similar results. In the present study, 24 UC was done and then urine was collected at 0800, 1100, 1400, 1700 and 1900 hours, with a daily salt intake of 6 g in 8 inpatients, 10 g in 11 inpatients or 15 g in 5 inpatients. In comparison with the 24 UC method, the CU method underestimated a high salt intake (15 g) when morning specimens were used and overestimated a low salt intake (6 g) when afternoon specimens were used. The correlation between the CU method and 24 UC method was weaker (R = 0.57) than that between the SMU method and 24 UC method (R = 0.85). In conclusion, the CU method is heavily influenced by the timing of urine collection and by the actual daily salt intake, so the SMU method provides a better estimate of individual salt intake.     

Usefulness of Self-Monitoring of Urinary Salt Excretion in Hypertensive Patients

We investigated the usefulness of measuring urinary salt excretion by using a self-monitoring device. Subjects were 34 hypertensive patients who underwent successful 24-h home urine collection five times and 25 volunteers. Four volunteers were diagnosed as having hypertension based on home blood pressure (BP) readings. All subjects were asked to measure daily urinary salt excretion for 30 days by using a self-monitoring device which estimates 24-h salt excretion by overnight urine. The mean urinary salt excretion during the 30 days was 8.36 ± 1.52 g/day and the range (maximum-minimum value) was 5.47 ± 20.05 g/day in all subjects. Mean urinary salt excretion decreased from 8.52 ± 1.63 g/day for the first 10 days to 8.31 ± 1.54 g/day for the last 10 days (p < 0.05). The mean urinary salt excretion determined by a self-monitoring device using overnight urine was positively associated with that determined by 24-h home urine for five times in the hypertensive subjects (r = 0.63, p < 0.01). Results indicate that a self-monitoring device seems to be useful to monitor daily salt intake and to guide salt restriction.     

Elevated Urinary T Helper 1 Chemokine Levels in Newly Diagnosed Hypertensive Obese Children

Objective:Increasing evidence suggests that T helper (Th) cells play a significant role in the pathogenesis of hypertension. The aim of this study was to evaluate the effect of obesity and anti-hypertensive treatment on urinary Th1 chemokines.Methods:The study groups consisted of three types of patients: hypertensive obese, healthy, and non-hypertensive obese. Pre-treatment and post-treatment samples of the hypertensive obese group and one sample from the other two groups were evaluated for urinary chemokine: regulated on activation, normal T cell expressed and secreted (RANTES), interferon-gamma-inducible protein 10 (IP10), and monokine induced by interferon-gamma (MIG). In the hypertensive obese group, urine microalbumin: creatinine ratio was examined before and after treatment. We recommended lifestyle changes to all patients. Captopril was started in those who could not be controlled with lifestyle changes and those who had stage 2 hypertension.Results:Twenty-four hypertensive obese (mean age 13.1), 27 healthy (mean age 11.2) and 22 non-hypertensive obese (mean age 11.5) children were investigated. The pre-treatment urine albumin: creatinine ratio was positively correlated with pre-treatment MIG levels (r=0.41, p<0.05). RANTES was significantly higher in the pre-treatment hypertensive and non-hypertensive obese group than in the controls. The urinary IP10 and MIG levels were higher in the pre-treatment hypertensive obese group than in the non-hypertensive obese. Comparison of the pre- and post-treatment values indicated significant decreases in RANTES, IP10, and MIG levels in the hypertensive obese group (p<0.05).Conclusion:Th1 cells could be activated in obese hypertensive children before the onset of clinical indicators of target organ damage. Urinary RANTES seemed to be affected by both hypertension and obesity, and urinary IP10 and MIG seemed to be affected predominantly by hypertension.     

Relationship between the awareness of salt restriction and the actual salt intake in hypertensive patients.

A 24-h home urine collection was conducted to estimate accurate salt intake in hypertensive outpatients. Using 24-h urinary creatinine excretion as a criterion for success, urine samples were obtained from 534 hypertensive patients. The urinary salt excretion of hypertensive outpatients ranged widely from 1.5 to 23.4 g/day (mean value 9.7 +/- 3.9 g/day). Urinary salt excretion was higher in males than in females (10.6 +/- 4.0 vs. 9.2 +/- 3.7 g/day, p<0.01). Based on the questionnaires, the patients were divided into salt-conscious patients, or those who were careful to reduce their daily salt intake, and non-salt-conscious patients. It was found that urinary salt excretion was lower in the salt-conscious group than in the non-salt-conscious group (9.4 +/- 3.8 vs. 10.6 +/- 4.0 g/day, p<0.01), but that urinary salt excretion adjusted for body weight was not significantly different between the two groups (0.16 +/- 0.06 vs. 0.17 +/- 0.07 g/kg/day). Our results suggest that there was no obvious reduction in the actual salt intake in salt-conscious patients, suggesting the importance of monitoring salt intake by 24-h home urine collection and informing patients of their actual salt intake as a means of encouraging the achievement of salt restriction.     

Does Low Urine Creatinine Level Indicate the Presence of Urine Alcohol in Methadone Maintenance Treatment Patients?

Objective: We sought to test the assumption that a low urine creatinine level is indicative of the presence of alcohol in the urine of patients prescribed methadone. Methods: This is a medical record review of 261,055 urine samples from approximately 6,000 patients prescribed methadone during a one-year period and for whom both urine creatinine and ethanol levels were simultaneously measured. We defined a creatinine level of less than 2.26 mmol/L as ‘low’ used a urine ethanol level of greater than 2.0 mmol/L as the reference standard for alcohol consumption. Results: The sensitivity and specificity of low urine creatinine as a marker for the detection of urine ethanol are 11.9% (95% CI: 11.3, 12.5%) and 96.7% (95% CI: 96.7, 96.7%), respectively. In this patient population with a low (3.6%) prevalence of alcohol in the urine, the results correspond to a positive predictive value of 11.9% (95% CI: 11.3, 12.6%) and a negative predictive value of 96.7% (95% CI: 96.7, 96.7%), respectively. Conclusions: Low urine creatinine is a poor screening test for detecting alcohol consumption among patients on methadone. However, a normal creatinine level has a 96.7% probability of no alcohol urine present in the urine.     

Estimation of salt intake and sodium-to-potassium ratios assessed by urinary excretion among Japanese elementary school children

Dietary salt intake is largely responsible for the increase in blood pressure with age. It is important to start effective prevention approaches during childhood. In this study, we estimated salt intake and sodium-to-potassium (Na/K) ratios assessed by urinary excretion among elementary school children in Kyoto, Japan. A total of 331 subjects aged 9–11 years participated in school checkups in April 2015. Urinary concentrations of sodium, potassium, and creatinine were measured in first morning urine samples. The subjects’ dietary habits were confirmed by questionnaires completed by their parents. The median estimated urinary sodium excretion was 129.0 mmol/day (5.7g/day of salt). In 30.2% of the subjects, their estimated salt intake exceeded their age-specific dietary goal for salt intake recommended by the Dietary Reference Intakes for Japanese 2015. Multivariate linear regression model analysis after adjustment for age revealed a significant positive correlation between seaweeds or fish paste products consumption and the estimated salt intake (p = 0.02 and 0.02, respectively). The median urinary Na/K ratio (mEq/mEq) was 4.5. Multivariate linear regression model analysis revealed a significant negative correlation between fruit consumption and urinary Na/K ratio (p = 0.04). These results suggest that the high sodium intake and the high Na/K ratios occur among Japanese elementary school children, and that the urinary Na/K ratio in children may be reduced by the daily consumption of fruit.     

Effectiveness of a spot urine method in evaluating daily salt intake in hypertensive patients taking oral antihypertensive drugs.

Kawasaki et al. developed a spot urine method (SUM) for evaluating daily salt intake using one pre-breakfast sample obtained after initial voiding upon arising. Their subjects were healthy persons who were not taking any regular medications. To determine whether SUM can be successfully used for patients taking antihypertensive drugs, we estimated daily salt intake in 73 hypertensive patients by SUM and by a food consumption method (FCM) when they were at home, and also by SUM in the hospital with a defined intake of 7 g of sodium chloride (NaCl). Forty-one patients took oral antihypertensive medications once daily, while 32 patients took none. Mean daily salt intakes by SUM during admission were 7-8 g of NaCl in both groups (95% confidence intervals: 5.0-10.6 g in the medication group; 5.2-11.1 g in the no-medication group), which corresponded well to the diet. In contrast, ambulatory daily salt intake by SUM varied widely (95% confidence intervals: 5.5-20.7 g in the medication group; 7.6-22.8 g in the no-medication group). However, the daily salt intakes determined by SUM and FCM correlated significantly with each other in the medication group (r=0.69, p<0.01) and the no-medication group (r=0.66, p<0.01). SUM is therefore a reliable method for evaluating daily salt intake in patients taking antihypertensive medication as well as unmedicated patients.     

Impact of fractional excretion of sodium on a single morning void urine collection as an estimate of 24‐hour urine sodium

The standard for assessing dietary sodium intake is to measure 24‐hour urine sodium. On average, 93% of daily sodium intake is excreted over 24‐hours. Expense and difficulties in obtaining complete 24‐hour collections have led to the measurement of sodium concentration in spot and single‐void urine samples, using predictive equations to estimate 24‐hour urine sodium. Although multiple predictive equations have been developed, in addition to having an average bias, all the equations overestimate 24‐hour sodium at lower levels of 24‐hour sodium and underestimate 24‐hour urine sodium at higher levels of 24‐hour sodium. One of the least biased estimating equations is the INTERSALT equation, which incorporates a spot urine creatinine concentration. The authors hypothesized that differential fractional excretion of sodium (FeNa)(derived from a morning void collection) relative to creatinine would impact on the accuracy of the INTERSALT equation in estimating 24‐hour urine sodium. In a prospective study of 139 adults aged 65 years and over, three sequential morning void and 24‐hour urine samples were examined. There was a significant correlation between increasing FENa and the difference between estimated and measured 24‐hours urine sodium (r = 0.358, P < .01). In the lowest quartile of FENa, the INTERSALT equation overestimated 24‐hour urine sodium, but underestimated 24‐hour urine sodium with greater magnitude in each of the subsequent quartiles of FENa. Differential excretion of sodium relative to creatinine, potentially impacted by renal blood flow and hydration, among other factors, affected the accuracy of the INTERSALT equation. Additional research may refine the INTERSALT and other predictive equations to increase their accuracy.     

Comparisons of spot vs 24-h urine samples for estimating population salt intake: Validation study in two independent samples of adults in Britain and Italy

ObjectivesTo assess the reliability and reproducibility of estimations of group mean 24-h urinary sodium (Na) excretion through timed spot urines compared to 24 h urinary Na output in two independent cross-sectional population samples including men and women and different ethnic groups.Methods and ResultsStudy 1 was carried out in Britain and included 915 untreated 40–59 yrs male and female participants (297 white, 326 of black African origin and 292 South Asian). Study 2 was carried out in Italy and included 148 white men (mean age 58.3 yrs). All participants provided both a 24-h urine collection and a timed urine sample as part of population surveys. Na, creatinine (Cr) and volume (V) were measured in all samples. Age, body mass index (BMI) and blood pressure (BP) were also measured. We compared the daily Na excretion through 24-h urine (gold standard) with its estimate from timed urine samples with two methods: Tanaka's predictions and Arithmetic extrapolations, and assessed them with correlation coefficients, Bland–Altman plot, prediction of quintile position and Receiver Operating Characteristic (ROC) Areas Under the Curve (AUC) for a cut-off of <100 mmol of Na/day. In Study 1 (discovery study) with the Tanaka method there were poor correlations between predicted and measured 24-h Na excretions in different ethnic groups and genders (r_Spearman from 0.055 [R² = 0.003] in black women to 0.330 [R² = 0.11] in white women). The Bland–Altman plots indicated consistent bias with overestimate for low and underestimate for high intakes. ROC AUCs varied from 0.521 to 0.652 with good sensitivity (95–100%) but very poor specificity (0–9%). With the Arithmetic extrapolations correlations varied from 0.116 [R² = 0.01] to 0.367 [R² = 0.13]. Bias was detected with both Bland–Altman plots and through quintile analyses (underestimate at low levels and overestimate at high levels). Finally, ROC AUCs varied from 0.514 to 0.640 with moderate sensitivity (64–70%) but low specificity (20–53%). In Study 2 (validation study) results were consistent with the discovery phase in white men.ConclusionBased on these results, 24-h urinary collection for the measurement of Na excretion remains the preferred tool for assessing salt intake when compared with reported methods based on timed spot urine samples.     

Trend of salt intake measured by 24-hour urine collection samples among Iranian adults population between 1998 and 2013: The Isfahan salt study

Background and aimFew population-based studies conducted in the Eastern Mediterranean region assessed salt intake by the measurement of 24-h sodium urine excretion (24-hUNa). The current study aimed to assess the trend of mean salt intake in Iranian adults between 1998 and 2013.Methods and resultsThese cross-sectional studies were performed on 564, 157, 509 and 837 randomly selected healthy adults aged >18 years from Isfahan city, Iran, in 1998, 2001, 2007 and 2013, respectively. BP was measured using a mercury sphygmomanometer according to a standard protocol. Single 24-h urine was collected to assess 24-hUNa as a surrogate of salt intake, and 24-h urinary K (24-hUK).The estimated trend of salt intake was 9.5, 9.7, 9.6 and 10.2 g/day in total population (P < 0.001). The increase in salt intake between 1998 and 2013 was significant only in men, (P < 0.001). The risk of pre-hypertension was 21% and 18% significantly greater in the highest quartiles of UNa/UK after adjustment for potential confounders in 2001 and 2013, respectively, [OR (95% CI): 1.21 (1.03–1.64) and 1.18 (1.02–1.38), respectively].ConclusionsThis population-based study indicated that mean salt intake was about two times of recommendation in Isfahan city, Iran, and suggest that it would be essential to implement a salt reduction strategy program in Iranian population. Longitudinal national studies with larger samples examining the trend of salt intake are warranted.     

Long-term compliance with salt restriction in Japanese hypertensive patients.

The purpose of the present study was to investigate the long-term compliance with salt restriction in Japanese hypertensive patients. Subjects included 389 patients, 230 women and 159 men, mean age 58+/-11 years, who underwent successful 24-h home urine collection more than three times over an interval of a year. Urinary salt, potassium, and creatinine were measured. Additionally, family history, habitual alcohol intake, smoking habit, physical activities, and job status were assessed by use of a questionnaire. During the follow-up period (average 3.5 years), participants underwent urine collection 4.6 times in average. Urinary salt excretion at the last visit was significantly lower than that at the first visit (8.7+/-3.4 vs. 9.6+/-4.1 g/day; p<0.01). Urinary potassium excretion also decreased significantly during this period (from 2.0+/-0.7 to 1.9+/-0.7 g/day; p<0.05). Among the mean 4.6 urine collections, 45.2% (men 34.6%, women 52.6%) of the patients successfully achieved <6 g (100 mmol of sodium)/day of salt excretion on at least one occasion. The rate of achievement of averaged urinary salt excretion <6 g/day dropped to 10.3% (men 4.4%, women 14.3%). Only 2.3% (men 0.6%, women 3.5%) of the patients achieved <6 g/day on all occasions. There were no significant differences in age, habitual alcohol intake, smoking habit, physical activities, or job status between patients who complied with the salt-restricted diet and those who did not. Results suggest that long-term compliance with salt restriction is poor in Japanese hypertensive patients. Since no specifically defining characteristics were found in the compliant patients, repeated measurements of urinary salt excretion seem to be important to encourage salt restriction.     

Mise au point et évaluation de l’ExSel Test pour dépister une consommation excessive de sel chez les patients hypertendus

ObjectiveDevelopment of a test to screen excess salt intake (ESI) in hypertensive patients.MethodsHypertensive subjects living in Paris area have been included. A 24-hour urinary sodium collection has been performed the day before the visit for a day hospital. A food diary was completed on the day of the urine collection and validated after an interview with a dietetician. An ESI was defined by a urinary sodium ≥ 200 mmol/d. Clinical or food characteristics associated to an ESI were retained for the ExSel Test variables. A ROC curve was performed to determine the optimal score for the ExSel Test in detection of ESI in hypertensive patients.ResultsOne hundred and forty-eight hypertensive patients have been included living in the Île-de-France area. ESI was observed in 19% with a higher frequency in men. Seven major determinants of ESI have been identified and are the questions that constitute the ExSel Test. A positive response assigns points: man (1); BMI > 30 (2); bread 4 or 5 pieces per day (1) or more than 6 pieces; cheese at least 1 time per day (2); charcuterie at least 2 times per week (2); use of processed broth or pilaf (1); food rich in hidden salt (pizza, cheeseburger, quiche, shrimp, potato chips, smoked fish, olive) at least 2 times per week (1). The ROC curve analysis shows that a score of 5 or more has the best Youden index with a sensitivity of 0.63, specificity of 0.95, PPV of 0.75, NPV of 0.92.ConclusionsIn hypertensive subjects, an excessive salt intake can be detected by the realization of the ExSel Test based only on a simple food-questionnaire and some clinical parameters. For a clinical use of the ExSel Test, an electronic version is available on http://www.comitehta.org.     

High Salt Intake Is Independently Associated With Hypertensive Target Organ Damage

The authors tested the hypothesis that high salt intake is associated with hypertensive target organ damage (TOD) independent of blood pressure (BP), and oxidative stress is a modifying factor of this association. A total of 369 community‐dwelling Japanese adults (mean age, 67.5 years; 56.6% women) were examined in this observational study. At the patients' annual health check‐ups, urinary salt excretion (U‐SALT), 8‐hydroxy‐2′‐deoxyguanosine (8‐OHdG), and albumin‐creatinine ratio (UACR) were measured from first morning urine. U‐SALT (β=0.14, P=.016) and 8‐OHdG (β=0.13, P=.018) were both independently associated with logUACR. U‐SALT was associated with TOD independent of BP level, and oxidative stress may be a modifying factor in the association between high salt intake and TOD. The elevation of 8‐OHdG may be involved in the pathophysiology of TOD induced by salt intake.     

Trend of salt intake measured by 24-h urine collection in the Italian adult population between the 2008 and 2018 CUORE project surveys

Background and aimsThe WHO Global Action Plan for the Prevention of non-communicable diseases (NCDs) recommends a 30% relative reduction in mean population salt/sodium intake. The study assessed the trend in the habitual salt intake of the Italian adult population from 2008 to 2012 to 2018–2019 based on 24-h urinary sodium excretion, in the framework of the CUORE Project/MINISAL-GIRCSI/MENO SALE PIU’ SALUTE national surveys.Methods and resultsData were from cross-sectional surveys of randomly selected age and sex–stratified samples of resident persons aged 35–74 years in 10 (out of 20) Italian Regions distributed in North, Centre and South of the Country. Urinary sodium and creatinine measurements were carried out in a central laboratory. The analyses included 942 men and 916 women examined in 2008–2012, and 967 men and 1010 women examined in 2018–2019. The age-standardized mean daily population salt (sodium chloride) intake was 10.8 g (95% CI 10.5–11.1) in men and 8.3 g (8.1–8.5) in women in 2008–2012 and respectively 9.5 g (9.3–9.8) and 7.2 g (7.0–7.4) in 2018–2019. A statistically significant (p<0.0001) salt intake reduction was thus observed over 10 years for both genders, and all age, body mass index (BMI) and educational classes.ConclusionsThe average daily salt intake of the Italian general adult population remains higher than the WHO recommended level, but a significant reduction of 12% in men and 13% in women has occurred in the past ten years. These results encourage the initiatives undertaken by the Italian Ministry of Health aimed at the reduction of salt intake at the population level.     

Influence of Salt Intake on Target Organ Damages in Treated Hypertensive Patients

This study investigates the influence of salt intake on renin–angiotensin–aldosterone system and clarifies their role to the target organ damage in the treated hypertensive patients. Subjects were 188 treated hypertensive outpatients (96 females and 92 males, mean age 67 ± 11 y). Patients underwent 24-hour home urine collection to measure urinary salt excretion and proteinuria. Clinical blood pressure (BP) and blood chemistry including plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were determined. Left ventricular mass index (LVMI) was also determined by echocardiography. Average BP was 129 ± 16/68 ± 10 mm Hg with the use of 2.0 antihypertensive drugs on average. Urinary salt excretion, PRA, and PAC were 8.1 ± 3.2 g/day, 2.2 ± 2.8 ng/mL/h, and 112 ± 54 pg/mL, respectively. Even in the patients taking angiotensin receptor blocker or angiotensin-converting enzyme inhibitors (n = 146), 15.1% showed low PRA (<0.5 ng/mL/h) levels and salt excretion in these patients with low PRA (9.1 ± 4.2 g/day) did not differ from those with higher PRA levels (8.2 ± 2.6 g/day, NS). There was no correlation between salt excretion and PRA (r = 0.03, NS), while salt excretion showed a significant negative correlation to PAC (r = ?0.17, P < .05). Urinary salt excretion was also correlated with proteinuria (r = 0.25, P < .01) and LVMI (r = 0.16, P < .05). In the multivariate analysis, salt excretion contributed to proteinuria (P < .05) or LVMI (P = .11) independent of age, sex, serum creatinine, and BP levels. Results indicate that PRA levels were relatively low and unaffected by salt intake in Japanese patients treated with antihypertensive drugs. Since high salt intake was possibly associated with target organ damages, strict salt reduction should be encouraged.     

Salt intake,knowledge of salt intake,and blood pressure control in Chinese hypertensive patients

A cross–sectional study involving 2502 subjects was conducted to evaluate salt intake, knowledge of salt intake, and blood pressure control in hypertensive patients. The blood pressure control rate was 33.5% among the hypertensive patients. Of the patients, 69.9% had salt intake higher than 6 g/d. Overall 35.0% knew the recommended salt intake, and 94.9% knew that “excess salt intake can result in hypertension.” Altogether, 85.8% of patients had received health education related to a low–salt diet at some time. Patients who consumed less than 6 g/d of salt had a higher control rate than those who consumed more than 6 g/d (48.7% vs. 27.0%; χ² = 111.0; P < .001). Patients with knowledge of the recommended salt intake had a higher control rate than those without (45.8% vs. 26.9%; χ² = 91.3; P < .001). Our findings suggest a high salt intake and low blood pressure control rate among Chinese hypertensive patients. Knowledge of recommended salt intake is inappropriate for patients with education of a low–salt diet.