Excessive Dietary Sodium Intake Research Articles

Renin-angiotensin System (RAS)-mediated Antiobesity and Antihypertensive Effects of Korean Traditional Soybean Paste (Doenjang) in Rat Model of Diet-induced Obesity (P08-097-19)

ObjectivesHypertension is becoming more prevalent and one of the main cause is found in the increase of excessive dietary sodium intake. It is also risk factors for cardiovascular and kidney disease. Korean Traditional Fermented Food, doenjang, is made with high salt, so many of them are thinking that there is a lot of relation to hypertension despite reporting many health benefits. Our previous studies reported that doenjang have been associated effect of anti-obesity in human and animal study. Therefore, we expected that doenjang may have different effects on blood pressure and lipid metabolism compared to same concentrations of salt. MethodsIn this study, Sprague-Dawley rats divided into four groups, normal diet (ND), high fat diet (HD), high fat diet with 8% table salt (HDS), high fat diet with Doenjang contains 8% table salt (HDJ) for 13 weeks. The systolic blood pressure (SBP), serum chemistry, Na+ and K+ concentrations, liver and renal gene expressions were measured. ResultsDoenjang decreased systolic blood pressure (SBP), body weight and hepatic lipids. Serum chemistry, leptin and aldosterone levels were increased in HD and HDS groups while decreased in HDJ group. Results from analysing feces and urine, Na+, Ca+ and K+concentrations were changed by Doenjang. Furthermore, fatty acid synthesis-related genes expression was decreased in liver and downregulated the renin, AT1 receptor and ACE in renal cortex of doenjang treatment group. ConclusionsThese results suggest that doenjang may have anti-obesity and anti-hypertension through regulation of the renin angiotensin system. We believed that it is an important result of demonstrating that doenjang has health benefits regardless of salt content. Funding SourcesThis work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MEST) (No. 2018R1A2B6006477).

Abstract P252: The Effects of Sodium Reduction on Metabolism and Thirst

Background: Recent studies challenge the traditional understanding of sodium physiology. Some animal studies suggest that high sodium intake may induce catabolism, leading to weight loss. Other studies suggest that high sodium intake might reduce, rather than increase, thirst. Hypothesis: Higher sodium intake increases thirst, fluid intake, and sodium excretion without altering energy intake or lowering weight. Methods: In the DASH-Sodium feeding study, adults with pre- or stage 1 hypertension without antihypertensive medications, were randomly assigned to the DASH diet or a control diet. On their assigned diet, participants consumed each of three sodium levels for 4 weeks (randomized crossover design). Participants were provided all meals, but could drink water freely. Throughout the trial, calorie intake was adjusted to keep weight constant. The three sodium levels (at 2100 kcal/d) were: low (1150 mg), medium (2300 mg), and high (3450 mg). Weight, energy intake, self-reported thirst, urine volume, plasma renin, serum aldosterone, urine osmolality, and urine sodium excretion were assessed at the end of each period. Results: Among 412 participants (57% women, 57% black, mean age 48 yrs), weight increased slightly with higher sodium on the control diet, but not the DASH diet; energy intake did not vary across sodium levels in both diets ( P -trends > 0.34) ( Table ). In contrast, participants reported more thirst with high vs low sodium (both diets P -trends < 0.001) and potentially higher fluid intake (urine volume) during the control diet (1,566 vs 1,491 ml on high vs low sodium; P -trend = 0.07). On both diets, plasma renin and serum aldosterone were lower with higher sodium (each P -trend < 0.001). Likewise, both urine osmolality and sodium excretion were higher with higher sodium intake (all P -trends < 0.001). Conclusions: Higher sodium intake did not alter energy intake, but did increase thirst and sodium excretion. These findings are consistent with the traditional understanding of the physiology of excess dietary sodium intake.

Food Sources of Sodium Intake in an Adult Mexican Population: A Sub-Analysis of the SALMEX Study.

Excessive dietary sodium intake increases blood pressure and cardiovascular risk. In Western diets, the majority of dietary sodium comes from packaged and prepared foods (≈75%); however, in Mexico there is no available data on the main food sources of dietary sodium. The main objective of this study was to identify and characterize the major food sources of dietary sodium in a sample of the Mexican Salt and Mexico (SALMEX) cohort. Adult male and female participants of the SALMEX study who provided a complete and valid three-day food record during the baseline visit were included. Overall, 950 participants (mean age 38.6 ± 10.7 years) were analyzed to determine the total sodium contributed by the main food sources of sodium identified. Mean daily sodium intake estimated by three-day food records and 24-h urinary sodium excretion was 2647.2 ± 976.9 mg/day and 3497.2 ± 1393.0, in the overall population, respectively. Processed meat was the main contributor to daily sodium intake, representing 8% of total sodium intake per capita as measured by three-day food records. When savory bread (8%) and sweet bakery goods (8%) were considered together as bread products, these were the major contributor to daily sodium intake, accounting for the 16% of total sodium intake, followed by processed meat (8%), natural cheeses (5%), and tacos (5%). These results highlight the need for public health policies focused on reducing the sodium content of processed food in Mexico.

High dietary sodium intake is associated with low bone mass in postmenopausal women: Korea National Health and Nutrition Examination Survey, 2008-2011.

Several studies have reported that large amount of dietary sodium intake is highly associated with elevated urinary calcium. However, the direct effect of excessive dietary sodium intake on bone mass, as a risk factor for osteoporosis, is still a controversial issue. The aim of the present study was to assess the relationship between high intake of sodium and lower bone mass and risk of osteoporosis in adult women. This cross-sectional study was performed using data from the Korea National Health and Nutrition Examination Survey (KNHANES), 2008-2011. Participants (n=9526 women older than 18years) were divided into a premenopausal (n=4793) and postmenopausal (n=4733) group. Both groups were subdivided into five groups according to quintiles of energy-adjusted sodium intake. Multiple regression analysis was performed to assess relationships between sodium intake and lower bone mass. Multivariate linear regression analysis showed that high sodium intake was negatively associated with bone mineral content (BMC) and bone mineral density (BMD) in postmenopausal women. After adjusting confounding factors, high sodium intake was negatively associated with BMC and BMD of the lumbar spine in postmenopausal women. Postmenopausal women, whose sodium intake was ≥2000mg/day (odds ratio 1.284, 95% CI 1.029-1.603, P=0.027), were at risk of developing osteoporosis after adjustment of confounding variables. The present study suggested that high sodium intake could be a potential risk factor for low bone mass after adjusting for confounding factors in postmenopausal women.

Association between family history of diabetes and cardiovascular disease and lifestyle risk factors in the United States population: The 2009–2012 National Health and Nutrition Examination Survey

Family history is a well-known risk factor for diabetes and cardiovascular disease (CVD) and modification of lifestyle risk factors can significantly lessen such risk.Our aim was to assess the association between family history of diabetes and/or CVD and lifestyle behaviors and risk factors (smoking, low physical activity, excessive dietary sodium and cholesterol intake and obesity) in a nationally representative sample of U.S. adults.We conducted a cross-sectional analysis of the National Health and Nutrition Examination Survey (NHANES) 2009–2012. Family history, lifestyle behaviors and risk factors were defined using self-reported and physical examination data.The study sample included 10,988 participants with a mean age of 47years. Among the U.S. adult population, 29.5%, 5.7% and 6.5% had a family history of diabetes, CVD and both diseases respectively. Compared to participants with no family history, participants with a family history of diabetes, CVD and both diabetes and CVD were more likely to be current smokers (OR=1.18[95% CI, 1.03–1.35], OR=1.68[95% CI, 1.31–2.17] and OR=1.71[95% CI, 1.30–2.26] respectively). Participants with a family history of diabetes (OR=1.42[95% CI, 1.26–1.61]) and both diabetes and CVD were more likely to be overweight/obese (OR=2.06[95% CI, 1.57–2.69]). There was no association between family history and dietary factors or physical activity.In the U.S., there is a high prevalence of modifiable risk factors among persons with a family history of diabetes and/or CVD. Healthcare providers have a significant role to play in targeting these individuals for lifestyle changes.

Dietary Sodium Loading Increases Central Systolic Blood Pressure More in Middle‐Aged Compared to Young Salt Resistant Adults

Excess dietary sodium intake has been linked to increased incidence of cardiovascular disease and the development of hypertension. We sought to determine the effect of short‐term dietary sodium loading on central blood pressure in young (YG; n=46, 26±1 yrs) and middle‐aged (MA; n=27, 51±1 yrs) normotensive, salt resistant adults. Subjects were randomized to 7 days of low sodium (LS: 20 mmol/d) and 7 days of high sodium (HS: 300 mmol/d). Salt‐resistance was defined as mean 24‐hour MAP change 蠄5 mmHg between diets (LS: 87±1 vs. HS: 86±1 mmHg, p > 0.05). On the last day of each diet, carotid‐femoral pulse wave velocity (PWV) and the synthesis of a central aortic pressure waveform (by radial artery applanation tonometry and generalized transfer function) and wave separation analysis were performed. When compared to the LS diet, the HS diet elicited an increase in central systolic blood pressure (cSBP) in both YG (LS: 95±1 vs. HS: 98±1 mmHg, p < 0.05) and MA (LS: 107±2 vs. HS: 116±3 mmHg, p < 0.05), with a larger increase seen in MA (YG: 3±1 vs. MA: 9±2, p < 0.05). In MA, HS elicited greater central forward wave amplitude (LS: 26±1 vs. HS: 30±1 mmHg, p < 0.05) and central reflected wave amplitude (LS: 18±1 vs. HS: 22±1 mmHg, p < 0.05) but no difference was seen in YG. PWV was not altered by 7 days of HS in either group (p>0.05). These data suggest that higher sodium intake is associated with a greater increase in cSBP in MA compared to YG adults that may be due to increases in forward and reflected wave amplitudes.Supported by NIH Grant R01 HL104106

Sodium intake in US ethnic subgroups and potential impact of a new sodium reduction technology: NHANES Dietary Modeling.

BackgroundBecause excessive dietary sodium intake is a major contributor to hypertension, a reduction in dietary sodium has been recommended for the US population. Using the National Health and Nutrition Examination Survey (NHANES) 2007–2010 data, we estimated current sodium intake in US population ethnic subgroups and modeled the potential impact of a new sodium reduction technology on sodium intake.MethodsNHANES 2007–2010 data were analyzed using The National Cancer Institute method to estimate usual intake in population subgroups. Potential impact of SODA-LO® Salt Microspheres sodium reduction technology on sodium intake was modeled using suggested sodium reductions of 20-30% in 953 foods and assuming various market penetrations. SAS 9.2, SUDAAN 11, and NHANES survey weights were used in all calculations with assessment across age, gender and ethnic groups.ResultsCurrent sodium intake across all population subgroups exceeds the Dietary Guidelines 2010 recommendations and has not changed during the last decade. However, sodium intake measured as a function of food intake has decreased significantly during the last decade for all ethnicities. “Grain Products” and “Meat, Poultry, Fish, & Mixtures” contribute about 2/3rd of total sodium intake. Sodium reduction, using SODA-LO® Salt Microspheres sodium reduction technology (with 100% market penetration) was estimated to be 185–323 mg/day or 6.3-8.4% of intake depending upon age, gender and ethnic group.ConclusionsCurrent sodium intake in US ethnic subgroups exceeds the recommendations and sodium reduction technologies could potentially help reduce dietary sodium intake among those groups.

Left ventricular mass changes after renal transplantation: influence of dietary sodium and change in serum uric acid.

We hypothesized that dietary sodium may modulate the effect of systolic blood pressure and other nonhemodynamic factors, such as high uric acid and renal dysfunction, on changes in the left ventricular mass after renal transplantation. The objective of the present 3-year follow-up longitudinal study was to assess the concomitant influence of these factors on changes in the left ventricular mass after renal transplantation. Twenty-four-hour urinary sodium excretion, glomerular filtration rate (isotopic clearance), and left ventricular mass (echocardiography) assessment were done in 165 renal transplant patients during the first year and after a follow-up of 3 years after renal transplantation. At follow-up, therapy of hypertension was associated with normalization of blood pressure in 64% and a decrease in the prevalence of left ventricular hypertrophy from 66% to 56%. At baseline and follow-up, systolic blood pressure, sodium intake, and serum uric acid emerged as independent and significant determinants of the final left ventricular mass index. When the population was divided according to sex-specific tertiles of the final 24-hr urinary sodium excretion, the relationship between change in serum uric acid during follow-up, final left ventricular mass index, and final glomerular filtration rate was significant only on the highest tertile of 24-hr urinary sodium excretion. The decrease in the prevalence of left ventricular hypertrophy after renal transplantation is blunted by high sodium intake. Persistence of the left ventricular hypertrophy may result from the combined adverse influences of excessive dietary sodium intake and increased serum uric acid during follow-up despite pharmacological control of blood pressure.

Abstract MP16: The Validity of Predictive Equations for 24-Hour Urine Sodium Excretion Among Older Adults and Those with Hypertension: The MESA and CARDIA Urinary Sodium Study

Background: Excess dietary sodium (Na) intake is linked to adverse cardiovascular health; the population distribution of urinary sodium (UNa) values in the US is unknown. We examined the population distribution of UNa and the validity of existing equations predicting 24-h Na excretion from a single spot urine sample among older adults with and without hypertension. Methods: Demographic, anthropometric, lab, and diet data along with 24-h urine collections were obtained from 555 MESA and CARDIA participants aged 45-79y. One third provided a second 24-h urine collection. Four timed voids (morning, afternoon, evening, and overnight) and the 24-h collection were analyzed for Na, creatinine, potassium and chloride concentrations. We examined the distribution of 24-h excretion of each analyte overall and by gender-race subgroups and hypertensive (HTN) status. We then examined the mean differences (bias) and confidence intervals between measured 24-h UNa excretion and the predicted from spot urine using 4 published equations by specimen timing, race-gender subgroups, and HTN status. Results: Using preliminary data from 265 participants with completed laboratory analysis, 55% female, 61% Black, and 60% had HTN. Mean 24-h Na excretion was 4234 ± 1920 mg for white men, 2706 ± 1136 mg for white women, 3463 ± 1691 mg for Black men and 3415 ± 1635 mg for Black women and did not significantly differ by hypertensive status. Mean bias in predicting 24-h Na excretion overall ranged from -268 (95% CI: -443.5, -91.8) to 1045 (849.3, 1240.4) mg/d. (Table) Conclusion: Among this group of older adults and those with hypertension, the mean 24-h UNa excretion levels for all race-gender groups exceeded current recommendations of 2,300 mg/d, with significant variation by race and gender. All of the four published equations under or overestimated mean 24-h Na excretion when using a single, timed spot urine sample but using evening samples appeared to produce the least bias. These preliminary findings are tentative until confirmed with the full dataset.

Excess dietary sodium and inadequate potassium intake by hypertensive patients in Italy

The aim of the study was to assess the age-specific, sex-specific, and region-specific average sodium and potassium intake and its association with anthropometric characteristics in a sample of the Italian adult hypertensive population. A total of 1232 hypertensive patients were recruited consecutively by 47 centers recognized by the Italian Society of Hypertension. The enrolled participants were on stable antihypertensive treatment. Anthropometric indices, blood pressure, 24-h urinary sodium, and potassium excretion were measured and used as proxy for the average daily sodium and potassium intake. The average sodium intake was 172 mmol (or 10.1 g of salt/day) among men and 138 (or 8.1) among women, with no difference among geographical areas. Over 90% of men and 81% of women had a consumption higher than the recommended standard dietary intake of 5 g/day. The average potassium intake was 63 and 56 mmol, respectively in men and women, again without geographical differences, nearly 92% of men and 95% of women having an intake lower than the recommended intake (100 mmol/day or 3.9 g/day). There was a significant trend to a gradual decrease in sodium intake with age in both sexes (P <0.001). There was also a direct association between BMI and sodium intake in both sexes, this association being independent of age (P < 0.001). In this national sample of the Italian hypertensive population, dietary sodium intake was largely higher and potassium intake much lower than the recommended intakes, and this was true for all geographical areas. Overweight and obese hypertensive patients had particularly high sodium intakes.

Effects of subacute dietary salt intake and acute volume expansion on diastolic function in young normotensive individuals

Chronic excess salt intake may have blood pressure-independent adverse effects on the heart such as myocardial hypertrophy and fibrosis. Effects of subacute sodium loading with excess dietary salt on diastolic function in normotensive individuals have been conflicting and the mechanisms are poorly understood. Thirteen healthy normotensive subjects (age 24 ± 4 years) entered a 2-week crossover study with 1 week of a low-salt diet <10 mEq/day and 1 week of a high-salt diet >200 mEq/day. At the end of each study week, left ventricular dimensions, systolic, and diastolic function were assessed with echocardiography before and after 2 L of normal saline infusion. One week of high-salt and low-salt diets did not lead to differences in echocardiographic parameters of systolic or diastolic function, even after rapid volume expansion with saline infusion. The peak early diastolic strain rate (SR) increased after volume loading both after completion of low-salt (1.62 ± 0.23/s vs. 1.82 ± 0.14/s, P < 0.05) and high-salt diets (1.67 ± 0.16/s vs. 1.86 ± 0.22/s, P < 0.05). There was a positive correlation between the peak early diastolic SR and the cardiac index (r = 0.52, P = 0.017). In healthy normotensive individuals, subacute excess dietary sodium intake does not affect diastolic function. The peak early diastolic SR, similar to other mitral Doppler and tissue Doppler parameters of diastolic function, appears to be strongly dependent on pre-load.

Cultural implications of managing chronic illness: Treating elderly Chinese patients with heart failure

Dietary patterns are associated with morbidity and mortality of heart failure. Volume overload was the most common cause for re-hospitalization for heart failure patients. However, recommended preventive strategies of restricting excessive dietary sodium and fluid intake were found to be in vain. This study looks at the preventive dietary instructions from a cultural context, and examined the effects of sodium and fluid restriction on twelve elderly Chinese patients hospitalized with heart failure through a qualitative design. Four themes emerged from the data: medicine–food homology, salt and sodium as synonymous, activity intolerance but still wanting social connections, and barriers to asking questions. Results suggested that living with heart failure is a complex and changeable process for both patients and caregivers. Many patients reported low levels of understanding concerning their symptoms and heart function deterioration. The findings found that good communication requires cultural sensitivity, objective listening to the patient's narrative, and helping patients find meaning between their experiences and symptom control.

Dietary salt intake and stroke

Dietary salt intake and stroke

Improving the efficacy of RAAS blockade in patients with chronic kidney disease

Reduction of blood pressure and proteinuria by blockade of the renin-angiotensin-aldosterone system (RAAS) has been the cornerstone of renoprotective intervention for patients with chronic kidney disease (CKD) for many years. Despite the proven efficacy of RAAS blockade, however, the reduction in proteinuria is insufficient in many patients, and does not prevent further deterioration of renal function. Short-term studies have shown that a variety of treatment intensification strategies have a beneficial effect on blood pressure and proteinuria, including RAAS blockade using either dose escalation or multiple drugs, and restriction of dietary sodium. Large clinical trials have shown that RAAS blockade with multiple drugs does not improve patients' long-term renal or cardiovascular outcome. By contrast, two post-hoc analyses of landmark trials in nephrology show beneficial renal and cardiovascular effects from avoiding excessive dietary sodium intake during single-agent RAAS blockade therapy. The effects of dietary sodium restriction on renal or cardiovascular outcome still require prospective confirmation. However, current data support the implementation of lifestyle changes to reduce dietary sodium intake in combination with single-agent RAAS blockade, rather than dual-agent RAAS blockade, as a potent and feasible strategy to mitigate the burden of renal and cardiovascular disease in patients with CKD.

Excess dietary sodium and inadequate potassium intake in Italy: Results of the MINISAL study

ObjectiveAs excess sodium and inadequate potassium intake are causally related to hypertension and cardiovascular disease, the MINISAL-GIRCSI Program aimed to provide reliable estimates of dietary sodium and potassium intake in representative samples of the Italian population. Design and methodsRandom samples of adult population were collected from 12 Italian regions, including 1168 men and 1112 women aged 35–79 yrs. Electrolyte intake was estimated from 24 hour urine collections and creatinine was measured to estimate the accuracy of the collection. Anthropometric indices were measured with standardised procedures. ResultsThe average sodium excretion was 189 mmol (or 10.9 g of salt/day) among men and 147 mmol (or 8.5 g) among women (range 27–472 and 36–471 mmol, respectively). Ninety-seven % of men and 87% of women had a consumption higher than the WHO recommended target of 5g/day. The 24 h average potassium excretion was 63 and 55 mmol, respectively (range 17–171 and 20–126 mmol), 96% of men and 99% of women having an intake lower than 100 mmol/day (European and American guideline recommendation). The mean sodium/potassium ratio was 3.1 and 2.8 respectively, i.e. over threefold greater than the desirable level of 0.85. The highest sodium intake was observed in Southern regions. Sodium and potassium excretion were both progressively higher the higher the BMI (p < 0.0001). ConclusionsThese MINISAL preliminary results indicate that in all the Italian regions thus far surveyed dietary sodium intake was largely higher and potassium intake lower than the recommended intakes. They also highlight the critical association between overweight and excess salt intake.

Achieving salt restriction in chronic kidney disease.

There is consistent evidence linking excessive dietary sodium intake to risk factors for cardiovascular disease and chronic kidney disease (CKD) progression in CKD patients; however, additional research is needed. In research trials and clinical practice, implementing and monitoring sodium intake present significant challenges. Epidemiological studies have shown that sodium intake remains high, and intervention studies have reported varied success with participant adherence to a sodium-restricted diet. Examining barriers to sodium restriction, as well as factors that predict adherence to a low sodium diet, can aid researchers and clinicians in implementing a sodium-restricted diet. In this paper, we critically review methods for measuring sodium intake with a specific focus on CKD patients, appraise dietary adherence, and factors that have optimized sodium restriction in key research trials and discuss barriers to sodium restriction and factors that must be considered when recommending a sodium-restricted diet.

Optimal Dietary Strategies for Reducing Incident Hypertension

Hypertension is a heterogeneous disease process in which both genetic and environmental factors play an important role. Historically, one of the most important environmental determinants is dietary sodium intake,1 consumed mostly as sodium chloride (salt). In humans, excessive dietary sodium intake is etiologically related to the epidemics of prehypertension and hypertension. Moreover, excessive dietary sodium intake has been associated with left ventricular hypertrophy and alterations in the structure and function of large arteries and renal vascular beds, in part, independent of the effect of sodium on blood pressure.2 There is also evidence that dietary sodium may affect arteriolar stiffness and, ultimately, systolic and pulse pressures. However, this is not true in all patients and may be related to not only genetic variations and how sodium is handled by the kidneys but also other dietary nutrients that may, in part, offset the effects of dietary sodium. The study by Zhang et al3 suggests that another important environmental determinant of hypertension is dietary animal protein intake. The authors analyzed data from a prospective study of 87 293 nurses followed for 14 years and provide interesting new information that a diet with a higher net acid load was …

The Prescription of Peritoneal Dialysis

In addition to the maintenance of normal extracellular electrolyte composition, the prescription of continuous peritoneal dialysis (CPD) should address four other specific issues: (i) prevention of uremia by achievement of adequate clearance of azotemic substances, (ii) prevention of progressive expansion of the extracellular volume by adequate peritoneal ultrafiltration, (iii) prevention of loss of residual renal function, and (iv) prevention of deterioration of the peritoneal membrane structure and function. Urea clearance, in the form of Kt/V(Urea), is the index of removal of azotemic substances proposed by current guidelines. The target total (renal plus peritoneal) Kt/V(Urea) is >or=1.7 weekly. To provide the desired peritoneal Kt/V(Urea) (K(p)t/V(Urea)), the prescription of peritoneal dialysis must provide a daily drain volume (Dv) defined by the clearance equations as Dv = V x (K(p)t/V(Urea))/(D/P(Urea)), where V is body water obtained from published anthropometric formulas, K(p)t/V(Urea) = (1.7 - renal Kt/V(Urea))/7 and D/P(Urea) is the dialysate-to-plasma urea concentration ratio at the dwell time prescribed. Computer programs obtain the relevant D/P(Urea) values from formal studies of peritoneal transport. In the absence of these studies (for example, at initiation of CPD), D/P(Urea) values can be obtained from published studies with similar dwell times. Body size, indicated by V, is the major determinant of the K(p)t/V(Urea) limit provided by a given CPD schedule. Other obstacles to achievement of adequate urea clearance are created by poor patient compliance, inaccuracies of the anthropometric formulas estimating V, and mechanical complications of CPD that lead to retention of dialysate in the body. The main requirements for the prescription of adequate ultrafiltration are knowledge of the individual peritoneal transport characteristics, monitoring of urinary volume, and restriction of dietary sodium intake. Excessive dietary sodium intake is the major cause of extracellular volume expansion in CPD. Ideally, sodium intake should be kept at the level of total (peritoneal plus renal) sodium removal. Preventing the loss of residual renal function involves avoidance of nephrotoxic influences in the form of medications, radiocontrast agents, urinary obstruction and infection, and possibly other influences, such an elevated calcium-phosphorus product and anemia. Use of the lowest dialysate dextrose concentration that will allow adequate ultrafiltration is currently the most widespread practical measure of prevention of peritoneal membrane deterioration. Formulation of biocompatible dialysate is a major ongoing research effort and may greatly enhance the success of CPD in the future.

Relation of Dietary Salt and Aldosterone to Urinary Protein Excretion in Subjects With Resistant Hypertension

Experimental data indicate that the cardiorenal effects of aldosterone excess are dependent on concomitant high dietary salt intake. Such an interaction of endogenous aldosterone and dietary salt has not been observed previously in humans. We assessed the hypothesis that excess aldosterone and high dietary sodium intake combine to worsen proteinuria in patients with resistant hypertension. Consecutive subjects with resistant hypertension (n=84) were prospectively evaluated by measurement of 24-hour urinary aldosterone (Ualdo), sodium, and protein (Uprot) excretion. Subjects were analyzed according to aldosterone status (high: Ualdo >or=12 microg/24 hours; or normal: <12 microg/24 hours) and dietary salt intake based on tertiles of urinary sodium. The mean clinic blood pressure for all of the subjects was 161.4+/-22.4/89.8+/-13.5 mm Hg on an average of 4.3 medications. There was no blood pressure difference between study groups. Uprot was significantly higher in the 38 subjects with high Ualdo compared with the 46 subjects with normal Ualdo (143.0+/-83.8 versus 95.9+/-81.7 mg/24 hours; P=0.01). Among subjects with high Ualdo, Uprot increased progressively across urinary sodium groups (P<0.05). In contrast, there was no difference in Uprot across sodium tertiles among subjects with normal Ualdo. A positive correlation between Uprot and urinary sodium (r=0.47; P=0.003) was observed in subjects with high Ualdo but not in subjects with normal Ualdo (r=0.18; P value not significant). These results suggest that aldosterone excess and high dietary salt combine to increase urinary protein excretion.

Epidemiology of blood pressure and predictors of hypertension.

Hypertension is a clinical disease with a prevalence sufficiently high in acculturated societies to warrant it being designated a serious public health problem. In population studies, blood pressure has been found to be a continuously distributed risk variable with mortality directly related to the level of blood pressure. Thus, hypertension is both a disease and a risk factor. Classic genetic studies suggest that the predisposition for the development of hypertension is an inherited trait that becomes manifest when coupled with one or more environmental insults. Risk factors for hypertension include age, weight, sedentary lifestyle, excessive dietary sodium intake, and excessive alcohol intake. Current and future research is being directed toward the identification of predictors of hypertension that can be conceptualized according to demographic, clinical, genetic, challenge-response, and laboratory predictors. The intent is to identify subjects with a high probability for the development of hypertension in advance of the rise in blood pressure so that appropriate interventions can be implemented as early as possible.