Daily salt intake is an independent risk factor for pollakiuria and nocturia

Association between nocturnal polyuria and 24-h blood pressure fluctuations in males with lower urinary tract symptoms: A multicenter prospective study

OBJECTIVES

Nocturnal polyuria (NP) is one of the causes of nocturia that impairs quality of life. It is necessary to consider that NP is latent when the initial treatment for nocturia is unsatisfactory. Therefore, it is important to establish a treatment for NP based on the pathophysiology. We have previously reported the relationship between NP and fluctuation in blood pressure. The present study aimed to investigate the association between NP and 24-h blood pressure fluctuations in a multicenter prospective study.

METHODS

This study included male patients with lower urinary tract symptoms. We categorized the patients into the nonnocturnal polyuria (non-NP) group (≤0.33) and the NP group (>0.33) based on the nocturnal polyuria index from the frequency volume chart. We measured the 24-h diurnal blood pressure and compared the two groups.

RESULTS

Among 90 patients, 46 in the non-NP group and 44 in the NP group were included. There was no significant difference in the systolic and diastolic blood pressure during waking time between the two groups; however, the degree of systolic blood pressure reduction during sleep time in the NP group was significantly less than that in the non-NP group (p = 0.039). In the multivariate analysis, systolic BP during sleep was significantly associated with NP (OR 0.970, p = 0.028).

CONCLUSION

NP is associated with inadequate nocturnal blood pressure reduction in males, suggesting that reduction in nocturnal blood pressure may lead to improvement in nocturia.

Reasons for Discontinuing Treatment with Sodium-Glucose Cotransporter 2 Inhibitors in Patients with Diabetes in Real-World Settings: The KAMOGAWA-A Study

Sodium-glucose cotransporter 2 inhibitors (SGLT2is) are a class of antidiabetic agents known to exert cardioprotective, renoprotective, and hypoglycemic effects. However, these agents have been associated with adverse effects, such as genital infection, volume depletion, hypoglycemia, and diabetic ketoacidosis, resulting in drug discontinuation. Herein, we aimed to determine the reasons for discontinuing treatment with SGLT2is among Japanese patients with diabetes. This retrospective cohort study enrolled 766 patients with diabetes who had initiated SGLT2is between January 2014 and September 2021. The follow-up period was 2 years from the initiation of the SGLT2is. Overall, 97 patients (12.7%) discontinued the SGLT2is during the follow-up period. The most common reasons for discontinuing the SGLT2is were frequent urination (19.6%), followed by genital infection (11.3%), improved glycemic control (10.6%), and renal dysfunction (8.2%). A comparison of the characteristics between the continuation and the discontinuation group was conducted, excluding those who discontinued the SGLT2is because of improved glycemic control. The patients in the discontinuation group (68 [55-75] years) were older than those in the continuation group (64 [53-71] years; p = 0.003). Importantly, we found no significant association between diabetes duration, diabetic control, renal function, or complications of diabetes in both groups. This real-world study revealed that frequent urination was the most common reason underlying SGLT2i discontinuation among Japanese patients with diabetes. To avoid discontinuation, precautions against various factors that may cause frequent urination must be implemented.

Nutritional Considerations for Bladder Storage Conditions in Adult Females

BACKGROUND

Clinical guidelines developed by urologic, urogynecologic, and gynecologic associations around the globe include recommendations on nutrition-related lifestyle and behavioral change for bladder storage conditions. This study identified and compared clinical guidelines on three urological conditions (interstitial cystitis/bladder pain syndrome (IC/BPS), overactive bladder, and stress urinary incontinence) affecting adult women.

METHODS

A three-step process was employed to identify the guidelines. Next, a quality assessment of the guidelines was conducted employing the Appraisal of Guidelines Research and Evaluation (AGREE II) International tool. (3) Results: Twenty-two clinical guidelines, prepared by seventeen groups spanning four continents, met the inclusion criteria. The AGREE II analyses revealed that most of the guideline development processes complied with best practices. The most extensive nutrition recommendations were for women with IC/BPS. Dietary manipulation for the other two storage LUTS primarily focused on the restriction or limitation of specific beverages and/or optimal fluid intake. (4) Conclusion: Clinical guidelines for IC/BPS, overactive bladder, and stress urinary incontinence include nutrition recommendations; however, the extent of dietary manipulation varied by condition. The need to ensure that clinicians are informing patients of the limitations of the evidence supporting those recommendations emerged. Furthermore, given the need to treat nutrition-related comorbid conditions as a strategy to help mitigate these three urological disorders, the value of referral to a dietitian for medical nutrition therapy is apparent.

Dietary sodium intake and its relation to sleep duration, sleep quality and nocturnal urination in working-aged Korean adults

Both sodium intake and sleep have an important effect on cardiovascular health. However, few studies have looked at the association between sodium intake and sleep. Therefore, we analysed the association of sodium intake with sleep quality, sleep duration and nocturnal urination. The data for the present study were obtained from the Kangbuk Samsung Health Study. Study participants were 156 696 working-aged Korean adults (average age 38.0 years ±8.0 in men and 36.0 years ±8.1 in women). They were categorised into five groups by quintile of sodium intake, measured by food frequency questionnaire. Poor sleep quality and short sleep duration were determined by Pittsburgh Sleep Quality Index >5, and sleep duration <7 h, respectively. Nocturnal urination was defined as awakening to urinate more than three times a week. Multivariable adjusted logistic regression analysis was used in calculating the odds ratio (OR) and 95% confidence interval (CI) for poor sleep quality, short sleep duration and nocturnal urination (adjusted OR [95% CI]) across five study groups. In all study participants, increased sodium intake was significantly associated with poor sleep quality (quintile 1: reference, quintile 2: 1.07 [1.04-1.11], quintile 3: 1.12 [1.08-1.16], quintile 4: 1.15 [1.11-1.19] and quintile 5: 1.13 [1.09-1.18]). This pattern of relationship was similarly observed in association of sodium intake with short sleep duration (p for trend <0.001) and nocturnal urination (p for trend <0.001). In gender subgroup analysis, increased sodium intake had a significant association with poor sleep quality and short sleep duration in men and with poor sleep quality and nocturnal urination in women. In conclusion, high sodium intake is associated with an increased likelihood of poor sleep quality, short sleep duration and nocturnal urination.

Age and metabolic syndrome are associated with unsatisfactory improvement in nocturia after holmium laser enucleation of the prostate

Objective

To investigate the association between age, metabolic syndrome (MetS) and improvement in nocturia in patients with benign prostate hyperplasia (BPH) receiving holmium laser enucleation of the prostate (HoLEP).

Methods

The retrospective study was conducted on patients treated for BPH using HoLEP between January 2021 and May 2022. Lower urinary tract symptoms (LUTS) were measured before surgery and at 3 months postoperatively using the International Prostate Symptom Score (IPSS). The criteria of the Adult Treatment Panel III (ATP III) were adopted to diagnose the MetS. Unsatisfactory improvement in nocturia was defined as <50% reduction in nocturia from baseline on the IPSS.

Results

One hundred and seventy-five patients were eventually enrolled, with a median age of 69 years (IQR: 63/73). Unsatisfactory improvement in nocturia was reported in 95 patients (54%) after HoLEP. These patients were older (73; IQR: 67/79 vs. 66; IQR: 60/71, P < 0.001) and more likely to present with higher postoperative total (6; IQR: 4/9 vs. 3; IQR:2/5, P < 0.001), voiding (1; IQR: 0/3 vs. 1; IQR: 0/2, P = 0.017), and storage (4; IQR: 3/6 vs. 2; IQR: 1/4, P < 0.001) IPSS when compared to patients with satisfactory improvement in nocturia. Overall, 63 of 175 (36%) patients were diagnosed with MetS and of these, 44 (70%) reported unsatisfactory improvement in nocturia (P = 0.002) after HoLEP. Multivariate analysis revealed that age (OR = 1.117, 95% CI: 1.068-1.169, P < 0.001) and MetS (OR = 3.613, 95% CI: 1.727-7.562, P = 0.001) were independent risk factors for unsatisfactory improvement in nocturia after HoLEP.

Conclusion

Our findings suggest that increased age and MetS were associated with unsatisfactory improvement in nocturia in patients with BPH after HoLEP. Lifestyle management, including weight loss, may be of great importance in the improvement of nocturia.

Reduced salt intake partially restores the circadian rhythm of bladder clock genes in Dahl salt-sensitive rats

AIMS

To examine the circadian expression changes in bladder clock genes in Dahl salt-sensitive rats following high salt intake.

MAIN METHODS

Eighteen rats were divided into three groups: the high-salt diet group (HS group), the normal-salt diet group (NS group), and the salt-load interruption group (from a 4 % salt diet to a normal diet; salt-load interruption group [SI group]). Each rat was placed in an individual metabolic cage for 24 h twice weekly. Water intake, urine production, voiding frequency, and voided volume per micturition were recorded. Furthermore, 108 control rats were prepared. Bladders were harvested every 4 h at six time points. Furthermore, the mRNA expression of clock genes and mechanosensors was analyzed.

KEY FINDINGS

In the HS group, the bladder clock genes showed lower mRNA levels than in the NS group. The amplitude of circadian expression changes in bladder clock genes in the HS group was lower than that in the NS group. However, after changing from a 4 % salt diet to a normal diet, the waveforms of the clock gene expression in the SI group were closer to those of the NS group. The 24-hour water intake and urinary volume of the SI group decreased to levels comparable to those of the NS group.

SIGNIFICANCE

Reduced salt intake partially restored the circadian rhythms of bladder clock genes.

Relationship between Urinary Calcium Excretion and Lower Urinary Tract Symptoms

To date, few detailed studies have been conducted on the convenient and useful markers for the prevalence of lower urinary tract symptoms (LUTS), including overactive bladder (OAB) and nocturia. A high level of calcium (Ca) excretion (hypercalciuria) is indicative of lifestyle-related diseases such as hypertension, which are associated with the onset of LUTS. Hence, in this study we attempted to clarify the relationship between urinary Ca excretion and OAB, nocturia, and nocturnal polyuria in adults. The present study showed that patients with hypercalciuria frequently experienced OAB, nocturia, and nocturnal polyuria. In addition, this study revealed that the severity of LUTS is significantly associated with urinary Ca excretion and that hypercalciuria is an important risk factor for OAB, nocturia, and nocturnal polyuria.

Dietary salt with nitric oxide deficiency induces nocturnal polyuria in mice via hyperactivation of intrarenal angiotensin II-SPAK-NCC pathway

Nocturnal polyuria is the most frequent cause of nocturia, a common disease associated with a compromised quality of life and increased mortality. Its pathogenesis is complex, and the detailed underlying mechanism remains unknown. Herein, we report that concomitant intake of a high-salt diet and reduced nitric oxide (NO) production achieved through N^ω-Nitro-L-arginine methyl ester hydrochloride (L-NAME) administration in mice resulted in nocturnal polyuria recapitulating the clinical features in humans. High salt intake under reduced NO production overactivated the angiotensin II-SPAK (STE20/SPS1-related proline–alanine-rich protein kinase)-NCC (sodium chloride co-transporter) pathway in the kidney, resulting in the insufficient excretion of sodium during the day and its excessive excretion at night. Excessive Na excretion at night in turn leads to nocturnal polyuria due to osmotic diuresis. Our study identified a central role for the intrarenal angiotensin II-SPAK-NCC pathway in the pathophysiology of nocturnal polyuria, highlighting its potential as a promising therapeutic target.

This study reports a mouse model of nocturnal polyuria - increased urine production at night that causes compromised quality of life and may impact mortality in older people. The authors identify a molecular pathway in the kidney that could prove to be a promising drug target for nocturnal polyuria.

Nocturia and Chronic Kidney Disease: Systematic Review and Nominal Group Technique Consensus on Primary Care Assessment and Treatment

CONTEXT

Reduced renal function impairs salt and water homeostasis, which can drive nocturnal or 24-h polyuria. Nocturia can arise early in chronic kidney disease (CKD). Evidence-based recommendations can facilitate management outside nephrology clinics.

OBJECTIVE

To conduct a systematic review (SR) of nocturia in CKD and achieve expert consensus for management in primary care and in specialist clinics outside nephrology.

EVIDENCE ACQUISITION

Four databases were searched from January 2000 to April 2020. A total of 4011 titles and abstracts were screened, and 108 studies underwent full-text screening. Seven studies met the inclusion criteria and two were identified through other sources. Consensus was achieved among an expert panel with public involvement using the nominal group technique (NGT).

EVIDENCE SYNTHESIS

Several plausible mechanisms contribute to nocturnal or 24-h polyuria in CKD, but there is little evidence on interventions to improve nocturia. NGT assessment recommendations for nocturia (at least two voids per night) in patients with CKD or at risk of CKD being assessed in a non-nephrology setting are: history (thirst, fluid intake), medication review (diuretics, lithium, calcium channel antagonists, nonsteroidal anti-inflammatory medications), examination (oedematous state, blood pressure), urinalysis (haematuria and albumin/creatinine ratio), blood tests (blood urea, serum creatinine and electrolytes, estimated glomerular filtration rate), and a bladder diary. Renal ultrasound should follow local CKD guidelines. Treatment options include optimising blood pressure control, dietary adjustment to reduce salt intake, fluid advice, and a medication review. Referral to specialist nephrology services should follow local guidelines.

CONCLUSIONS

CKD should be considered when evaluating patients with nocturia. The aim of assessment is to identify mechanisms and instigate therapy, but the latter may be more applicable to reducing wider morbidity associated with CKD than nocturia itself.

PATIENT SUMMARY

People with kidney disease can suffer severe sleep disturbance because of a need to pass urine overnight. We looked at published research and found some useful information about the underlying mechanisms. A group of experts was able to develop practical approaches for assessing and treating this condition.

The Influence of Salt Sensitivity Phenotype on Sodium Excretion and Diuresis: A Chrononutrition Pilot Study

BACKGROUND

Chrononutrition studies on interaction of diet/nutrients on endogenous circadian clocks and meal timing on metabolic homeostasis may be of importance in the management of nocturnal polyuria (NP), owing to loss of circadian rhythm in nighttime urination. Dietary salt restriction is an increasingly popular lifestyle recommendation for NP patients.

AIM

This study aims to evaluate the effect of an acute salt load on diuresis and to study the phenomenon of salt sensitivity. Methodology. Young, healthy men (n = 21, fasted and sober) ingested 500 ml of water on the control day and 8 g and 12 g of salt with water (500 ml) on two other days. Blood and urine samples were collected at 0 hrs, 2 hrs, and 4 hrs and voided volumes were recorded. Diuresis, serum and urine osmolality, sodium, potassium, urea, and creatinine were measured. Salt sensitivity was determined based on the rate of sodium excretion.

RESULTS

Compared to 8 g, ingestion of 12 g of salt significantly increased diuresis after 4 hrs. Pure water load induced fast diuresis, whereas salt and water load initially reduced diuresis and promoted late increase in diuresis. The total voided volume was significantly lower in the salt sensitive individuals.

CONCLUSION

Taken together, salt sensitivity profile and type and time of fluid intake are important considerations to build effective personalized lifestyle recommendations for NP patients, which needs further investigation.

The effects of choreito on a model of nocturnal polyuria using Dahl salt-sensitive rats

OBJECTIVES

This study aimed to determine whether Dahl salt-sensitive rats fed a high-salt diet would show features of nocturia due to nocturnal polyuria and to examine the efficacy of choreito (CRT) on nocturnal polyuria.

METHODS

Dahl salt-sensitive rats were divided into three groups. Group A was fed a 4% salt diet, group B a 2% salt diet, and group C a normal 0.3% salt diet. In groups α and β, other rats were further divided into two groups: The rats in group α were fed a 2% salt plus 3% CRT diet, and those in group β, were fed a 2% salt diet. Each rat was placed in an individual metabolic cage for 24 hours every week for 6 weeks. Water intake, urine production, voiding frequency, and voided volume per micturition were recorded.

RESULTS

The systolic blood pressure increased in the group fed a 4% salt diet compared to groups fed with a 2% and 0.3% salt diet. The urinary volume was higher in the groups fed with 4% and 2% salt than in the group fed with 0.3% salt. Further, water intake in the group fed a 2% salt plus 3% CRT diet was significantly lower than that in the group fed with a 2% salt diet.

CONCLUSIONS

Dahl salt-sensitive rats fed a 2% salt diet were candidates for a model of nocturnal polyuria. Using this model, we suggest that CRT reduces water intake in the active phase and contributes to water restriction in the treatment of nocturnal polyuria.

Hypertension, cardiovascular disease, and nocturia: a systematic review of the pathophysiological mechanisms

Nocturia significantly impairs quality of life, especially in the elderly population, and urinary retention is a main target of treatment for urologists. In addition to nocturia, cardiovascular diseases are common in the elderly population, and a systematic review showed that hypertension and heart failure are often associated with nocturia. One possible pathogenic mechanism underlying the development of hypertension is an increase in blood pressure due to excessive salt intake in people with high-salt sensitivity. From Guyton's natriuretic curve, we can infer that salt-sensitive hypertensive patients who consume too much salt do not excrete salt during the daytime and are forced to excrete salt at night, resulting in increased urine production and nocturia. In patients with heart failure, the nocturnal supine position leads to an increase in central fluid volume due to an increase in venous return from the periphery, and the secretion of natriuretic peptide is stimulated by the stretching of the atria and ventricles. Thus, natriuresis due to hypertension and hydrodiuresis due to heart failure may cause nocturia, which can effectively be treated by the administration of thiazide diuretics and loop diuretics in the morning, respectively. Because cardiovascular diseases, such as hypertension and heart failure, can cause nocturia and because the treatment methods differ depending on the cause, it is necessary to pay close attention to nocturia in the management of lifestyle-related diseases, such as cardiovascular disease.

Association between female urinary urgency and aponeurotic ptosis: Results from a community-based cross-sectional study in Japan

AIMS

To investigate the relationship between urinary urgency (UU) and aponeurotic ptosis (AP) in a health promotion project.

METHODS

This cross-sectional study analyzed 658 women in Aomori, Japan. The presence of UU was evaluated using the Overactive Bladder Symptom Score. The distance from the light reflex on the cornea to the upper eyelid (margin reflex distance-1 [MRD-1]) was measured. AP was defined as MRD-1 of less than 2.0 mm. The daily salt intake amount was estimated using the dietary questionnaire. Daily salt intake was defined as excessive if it was 10 g/day or higher. Independent factors of UU and AP were analyzed via multivariable logistic regression model.

RESULTS

The number of women with UU and AP was 193 and 65, respectively. Similar background differences were observed in age, cardiovascular disease history, renal function, hypertension, diabetes mellitus, dyslipidemia, and daily salt intake between participants with UU and those with AP. Participants with UU had a higher prevalence of AP (19% vs. 6.2%) than those without. Moreover, more than 50% of the women with AP experienced UU. Multivariable logistic analysis on UU showed that age (≥65 years), diabetes mellitus, daily salt intake (≥10 g/day), and AP (odds ratio, 2.07, p = .014) were independent factors. Multivariable analysis on AP revealed that age (≥65 years), hypertension, daily salt intake (≥10 g/day), and UU were independent factors.

CONCLUSIONS

AP was an independent indicator of UU, in addition to excessive daily salt intake. Women with AP may tend to intake excessive salt and experience UU.

Decreased renal function increases the nighttime urine volume rate by carryover of salt excretion to the nighttime

To determine the pathophysiology of nocturnal polyuria associated with renal dysfunction, patients who underwent laparoscopic nephrectomy were prospectively studied. The diurnal variation in urine volume, osmolality, and salt excretion were measured on preoperative day 2 and postoperative day 7. The factors associated with an increase in the nighttime urine volume rate with decreased renal function were evaluated using multiple linear regression analysis. Forty-nine patients were included. The estimated glomerular filtration rate decreased from 73.3 ± 2.0 to 47.2 ± 1.6 mL/min/1.73 m² (P < 0.01) and the nighttime urine volume rate increased from 40.6% ± 2.0% to 45.3% ± 1.5% (P = 0.04) with nephrectomy. The nighttime urine osmolality decreased from 273 ± 15 to 212 ± 10 mOsm/kg and the nighttime salt excretion rate increased from 38.7% ± 2.1% to 48.8% ± 1.7% (both P < 0.01) with nephrectomy. Multiple linear regression analysis showed that the increase in the nighttime urine volume rate was strongly affected by the increase in the nighttime salt excretion rate. A decrease in renal function causes an increase in the nighttime urine volume rate, mainly because of an increase in nighttime salt excretion.

Trial registration number: UMIN000036760 (University Hospital Medical Information Network Clinical Trials Registry).

Date of registration: From 1 June 2019 to 31 October 2020.

Clinical Guidelines for Female Lower Urinary Tract Symptoms (second edition)

The present article is an abridged English translation of the Japanese Clinical Guidelines for Female Lower Urinary Tract Symptoms (second edition), published in September 2019. These guidelines consist of a total of 212 pages and are unique worldwide in that they cover female lower urinary tract symptoms other than urinary incontinence. They contain two algorithms for "primary treatment" and "specialized treatment," respectively. These guidelines, consisting of six chapters, address a total of 26 clinical questions including: (i) treatment algorithms; (ii) what are female lower urinary tract symptoms?; (iii) epidemiology and quality of life; (iv) pathology and illness; (v) diagnosis; and (vi) treatment. When the patient's symptoms mainly involve voiding and post-micturition symptoms, specialized treatment should be considered. In the event of voiding symptoms concurrent with storage symptoms, residual urine should be measured; if the residual urine volume is <100 mL, then diagnosis and treatment for storage symptoms is prioritized, and if the volume is ≥100 mL, then specialized treatment should be considered. When storage symptoms are the primary condition, then the patient is subject to the primary treatment algorithm. Specialized treatment for refractory overactive bladder includes botulinum toxin injection and sacral nerve stimulation. For stress urinary incontinence, surgical treatment is indicated, such as urethral slings. The two causes of voiding symptoms and post-micturition symptoms are lower urinary tract obstruction and detrusor underactivity (underactive bladder). Mechanical lower urinary tract obstruction, such as pelvic organ prolapse, is expected to improve with surgery.

Efficacy of salt reduction for managing overactive bladder symptoms: a prospective study in patients with excessive daily salt intake

This study aimed to investigate the efficacy of salt intake restriction on overactive bladder (OAB) symptoms in patients with excessive salt intake. Patients received a brochure on nutritional guidance regarding salt intake reduction and received health education every 4 weeks for 12 weeks. Data from overactive bladder symptom score (OABSS) questionnaires and frequency volume charts (FVCs) were evaluated. The daily salt intake was estimated by determining the urinary sodium and creatinine concentrations using spot urine samples. Of the 98 patients included, 71 (72.4%) successfully restricted their daily salt intake after 12 weeks (salt restricted [R] group), while 27 (27.6%) did not (salt non-restricted [N-R] group). The scores to each OABSS question and the resulting total score improved significantly in the R group; however, the individual scores remained unchanged and the total score increased in the N-R group. The FVC data indicated improved voided volumes in the R group as compared to in the N-R group. Ultimately, 17 (23.9%) patients in the R group no longer fulfilled the OAB diagnostic criteria after salt intake reduction. Thus, salt intake reduction improved urinary symptoms in patients with OAB and may be a therapeutic option for OAB in patients with excessive daily salt intakes.

Effects of High Salt Intake on Detrusor Muscle Contraction in Dahl Salt-Sensitive Rats

High salt intake has been reported as a risk factor for urinary storage symptoms. However, the association between high salt intake and detrusor muscle contraction is not clear. Therefore, we investigated the effects of high salt intake on the components of detrusor muscle contraction in rats. Six-week-old male Dahl salt-resistant (DR; n = 5) and Dahl salt-sensitive (DS; n = 5) rats were fed a high salt (8% NaCl) diet for one week. The contractile responses of the detrusor muscle to the cumulative administration of carbachol and electrical field stimulation (EFS) with and without suramin and atropine were evaluated via isometric tension study. The concentration-response curves of carbachol were shifted more to the left in the DS group than those in the DR group. Contractile responses to EFS were more enhanced in the DS group than those in the DR group (p < 0.05). Cholinergic component-induced responses were more enhanced in the DS group than those in the DR group (p < 0.05). High salt intake might cause urinary storage symptoms via abnormalities in detrusor muscle contraction and the enhancement of cholinergic signals. Excessive salt intake should be avoided to preserve bladder function.

Does cognitive behavioral therapy using a self-check sheet improve night-time frequency in patients with nocturia? Results of a multicenter randomized controlled trial

OBJECTIVE

To determine whether cognitive behavioral therapy using a self-check sheet is effective in improving night-time frequency of patients with nocturia.

METHODS

We carried out a multicenter, open-labeled, randomized controlled trial in eight institutions. Patients having two or more episodes of nocturia were randomly assigned to either cognitive behavioral therapy with completion of frequency volume charts regularly (cognitive behavioral therapy group) or frequency volume charts regularly alone (frequency volume charts group). The cognitive behavioral therapy checklist was composed of eight items: wake up time/bedtime, mealtime, napping, alcohol/caffeine intake, water intake, salt intake, exercise and taking a bath. A physician explained cognitive behavioral therapy within 5 min using a brief manual. The patients in the cognitive behavioral therapy group filled out the self-check sheet every day. The primary end-point was the difference in night-time frequency based on the International Prostate Symptom Score Q7 at 4 weeks.

RESULTS

Of the 100 first-visit patients randomly allocated, 37 in the cognitive behavioral therapy group and 41 in the frequency volume charts group completed the protocol. No difference was observed in the mean ± standard deviation of night-time frequency at 4 weeks between the cognitive behavioral therapy group (2.6 ± 1.0) and the frequency volume charts group (3.1 ± 1.2; P = 0.056). However, when six patients with achievement of cognitive behavioral therapy of <50% were excluded from the analysis, night-time frequency at 4 weeks was significantly lower in the cognitive behavioral therapy group (2.5 ± 1.0) than in the frequency volume charts group (3.1 ± 1.2; P = 0.027).

CONCLUSIONS

The efficacy of cognitive behavioral therapy using a self-check sheet for nocturia remains to be shown. However, strictly practicing cognitive behavioral therapy might be beneficial to these patients.

Dietary Sodium Intake and Health Indicators: A Systematic Review of Published Literature between January 2015 and December 2019

As the science surrounding population sodium reduction evolves, monitoring and evaluating new studies on intake and health can help increase our understanding of the associated benefits and risks. Here we describe a systematic review of recent studies on sodium intake and health, examine the risk of bias (ROB) of selected studies, and provide direction for future research. Seven online databases were searched monthly from January 2015 to December 2019. We selected human studies that met specified population, intervention, comparison, outcome, time, setting/study design (PICOTS) criteria and abstracted attributes related to the study population, design, intervention, exposure, and outcomes, and evaluated ROB for the subset of studies on sodium intake and cardiovascular disease risks or indicators. Of 41,601 abstracts reviewed, 231 studies were identified that met the PICOTS criteria and ROB was assessed for 54 studies. One hundred and fifty-seven (68%) studies were observational and 161 (70%) focused on the general population. Five types of sodium interventions and a variety of urinary and dietary measurement methods were used to establish and quantify sodium intake. Five observational studies used multiple 24-h urine collections to assess sodium intake. Evidence mainly focused on cardiovascular-related indicators (48%) but encompassed an assortment of outcomes. Studies varied in ROB domains and 87% of studies evaluated were missing information on ≥1 domains. Two or more studies on each of 12 outcomes (e.g., cognition) not previously included in systematic reviews and 9 new studies at low ROB suggest the need for ongoing or updated systematic reviews of evidence on sodium intake and health. Summarizing evidence from assessments on sodium and health outcomes was limited by the various methods used to measure sodium intake and outcomes, as well as lack of details related to study design and conduct. In line with research recommendations identified by the National Academies of Science, future research is needed to identify and standardize methods for measuring sodium intake.

Daily salt intake is associated with leg edema and nocturnal urinary volume in elderly men

AIMS

There is accumulating evidence that excessive salt intake contributes to nocturnal polyuria. We aimed to investigate the relationship between salt intake, leg edema, and nocturnal urine volume (NUV) to assess the etiology of nocturnal polyuria.

METHODS

A total of 56 men aged ≥60 years who were hospitalized for benign prostatic hyperplasia or with suspected prostatic cancer were enrolled. Urine frequency-volume charts of the patients were maintained, and they underwent bioelectrical impedance analysis twice daily (at 5:00 pm and 6:00 am) and examination of blood (brain natriuretic peptide levels) and urine (sodium and creatinine levels and osmotic pressure) samples once daily (at 6:00 am). Free-water clearance, solute clearance, and sodium clearance at night were measured, and daily salt intake was estimated.

RESULTS

The data of 52 patients were analyzed. Daily salt intake positively correlated with leg edema at 5:00 pm, differences in leg extracellular fluid levels between 5:00 pm and 6:00 am, and NUV, but not with diurnal urine volume. Partial correlation coefficients showed that salt intake was a factor of the correlation between NUV and change in extracellular volume in the legs between 5:00 pm and 6:00 am. A multivariate logistic model showed that sleep duration and sodium clearance were independent predictive factors for nocturnal polyuria.

CONCLUSIONS

Sodium intake correlates with diurnal leg edema and NUV in elderly men. These results provide evidence supporting sodium restriction as an effective treatment for nocturnal polyuria.

Sodium restriction improves nocturia in patients at a cardiology clinic

This study aims to determine whether dietary sodium restriction counseling decreases nocturnal voiding frequency in cardiology patients with concomitant nocturia. Patients who had established care at a cardiology clinic from 2015 to 2018 reporting ≥1 average nocturnal void(s) underwent a comprehensive sodium intake interview by their cardiologist, who provided them with individualized strategies for dietary sodium reduction and assessed adherence at follow-up. Average nocturnal voiding frequency and dietary adherence were documented in the medical record. A nocturia database was compiled for retrospective analysis. A total of 74 patients were included. Patients considered to be adherent with dietary sodium restriction at follow-up (n = 56) demonstrated a decrease in median nocturia frequency (2.5 [2.3-3.0] vs 1.0 [1.0-2.0] voids, P < .001). Among nonadherent patients (n = 18), median nocturia frequency did not significantly change from baseline to follow-up (2.0 [1.5-3.8] vs 2.0 [1.5-4.8] voids, P = .423). Median changes were significantly different between the adherent and nonadherent groups (P < .001). Examination of second follow-up available from 37 patients showed a continued effect. In conclusion, adherence with dietary sodium counseling appears to improve nocturia. Accordingly, dietary modification may represent an important adjunct therapy to lifestyle and pharmacologic interventions for decreasing nocturia frequency. Reduction in nocturnal voiding frequency may also reflect an additional benefit of dietary sodium restriction in accordance with best practice standards for cardiovascular disease.

Dietary considerations in the evaluation and management of nocturia

Aim: This narrative review investigates the effect of dietary intake on nocturnal voiding severity. The primary aims of this review are to provide a framework for future research and ultimately contribute to more comprehensive, lifestyle-centered guidelines for the management of nocturia.

Methods: A literature search was conducted in Web of Science, PubMed, and Google Scholar databases using the keywords “nocturia”, “diuresis”, “natriuresis”, “food”, “diet”, and “nutrients”.

Results: High fruit and vegetable consumption was negatively associated with nocturia. High intake of tea and dietary sodium showed a positive association with nocturia. Several foods have also been directly linked to changes in diuresis rate, glycemic control, and endogenous serum melatonin concentration, offering potential mechanisms for this observed effect. Overall quality of the evidence was low.

Conclusion: At present, there is limited evidence to suggest that certain foods, electrolytes, and specific compounds may contribute to the pathogenesis of nocturia. A greater understanding of the impact of food and nutrients on body fluid metabolism is needed to further refine the evaluation and treatment of nocturia.

High daily salt intake had a negative impact on how well nocturnal enuresis treatment worked on children aged 7-10 years

AIM

We investigated whether the daily salt intake of children with nocturnal enuresis influenced their response to 1-desamino-8-D-arginine vasopressin therapy.

METHODS

This study comprised 129 children (67.4% boys) with a median age of 9.2 years (range 7.2-10.4) with monosymptomatic nocturnal enuresis who were seen at Kansai Medical University Hospital, Osaka, Japan, from 2013 to 2017. Urinary sodium concentrations were determined using a spot urine test, and the children were divided into appropriate (n = 55) and excessive salt intake (n = 74) groups based on Japanese Government guidelines. After a month of therapy, the treatment responses were compared for 39 and 50 children, respectively.

RESULTS

There were no significant differences in the urea nitrogen-to-creatinine or calcium-to-creatinine ratios in the two groups. However, the excessive salt intake group showed a significantly reduced treatment response to the appropriate salt intake group. In addition, the excessive and appropriate salt intake groups showed median efficacy ratios of 8.2% and 21.8%, respectively, based on intention-to-treat analysis (P = 0.029) and 12.0% and 30.8% based on per-protocol analysis (P = 0.029).

CONCLUSION

High daily salt intake significantly reduced the efficacy of ddavp therapy for nocturnal enuresis and consumption should be controlled during treatment.

Haptoglobin 1-1 phenotype: A risk factor for 24-hours polyuria

BACKGROUND

Haptoglobin (Hp) displays three major phenotypes (Hp 1-1, Hp 2-2 and Hp 2-1). Hp 1-1 has been implicated in high blood pressure and salt sensitivity, and thus may mediate excess urine production.

AIM

To explore the relationship between Hp polymorphisms and polyuria (>40 mL/kg/24 hours).

METHODOLOGY

Post hoc analysis of a prospective observational study of subjects who completed a renal function profile between October 2011 and February 2015 (n = 170). Hp phenotypes were determined by starch gel electrophoresis using haemoglobin-supplemented serum. The distribution of Hp phenotypes in subjects with and without polyuria was compared to a reference group of the same geography and ethnic composition. Diuresis rate, sodium clearance and free water clearance were compared within and between phenotypes.

RESULTS

The Hp1 allele frequency was significantly overexpressed in subjects with polyuria compared to the reference group (0.500 vs 0.400, P < .05). Consistently, the Hp 1-1 phenotype was more prevalent in subjects with polyuria compared to the reference group (28% vs 16%, P < .05). In contrast to Hp 2-1/2-2, Hp 1-1 demonstrated no circadian variation in diuresis rate, sodium clearance or free water clearance. A significant association between plasma Hp concentration and 24-hours sodium clearance was observed in Hp 1-1 subjects without polyuria (β = 0.222; 95% CI 0.003-0.441; P = .047).

CONCLUSION

The Hp1 allele was more frequent in subjects with polyuria, and participants with the Hp 1-1 phenotype were at greater risk for polyuria. Hp 1-1 subjects demonstrated an altered ability to concentrate urine with a slower continuous excretion of sodium throughout the day. Plasma Hp concentration of Hp 1-1 was positively correlated with 24-hours sodium clearance in subjects without polyuria.

Future Considerations in Nocturia and Nocturnal Polyuria

Nocturnal polyuria (NP), the most common etiology of nocturia, can be caused by various medical conditions, including cardiovascular disease, obstructive sleep apnea, renal tubular dysfunction, as well as medications (eg, diuretics) and/or behavioral patterns. NP in the absence of underlying medical conditions has been described as NP syndrome and is thought be the result of impaired circadian release of endogenous arginine vasopressin. Desmopressin, a synthetic arginine vasopressin analog, has been shown to be an effective replacement therapy in adults with nocturia due to NP. Further studies on the subset of patients with NP syndrome are warranted to maximize benefit from antidiuretic treatment. In addition, a connection between the pathophysiological mechanisms underlying NP and essential hypertension has been suggested, and hypertension has been shown to be a significant risk factor for nocturia, while an association between NP and brain natriuretic peptide levels has also been reported in patients with nocturia. Hypertension is now viewed as a disorder of blood vessels and treatment is directed at the vasculature rather than the blood pressure, with the latter currently serving as a biomarker for arterial injury. Nocturia is thought to be associated with the beginning of this cardiovascular continuum as studies have reported a link between coronary heart disease and nocturia. Therefore, there is an increasing need to elucidate the complex mechanisms implicated in the association between nocturia and hypertension to promote the development of more individualized therapies for the treatment of nocturia.

Paucity of high-quality studies reporting on salt and health outcomes from the science of salt: A regularly updated systematic review of salt and health outcomes (April 2017 to March 2018)

The purpose of this review is to identify, summarize, and critically appraise studies on dietary salt and health outcomes that were published from April 2017 to March 2018. The search strategy was adapted from a previous systematic review on dietary salt and health. Identified studies were screened based on a priori defined criteria to identify publications eligible for detailed critical appraisals. Overall, 6747 citations were identified by the search strategy, and 42 health outcome studies were identified. Three of the 42 studies met the criteria for methodological quality and health outcomes and underwent detailed critical appraisals and commentary. In addition, a systematic review and meta-analysis was critically appraised, although it did not strictly meet our methodological criteria. All four of the studies critically appraised found that sodium reduction improved blood pressure, especially in individuals with hypertension. In addition, sodium reduction reduced albuminuria in patients with stage 1-3 chronic kidney disease. Examination of the time course of blood pressure responses to sodium reduction revealed lowering sodium in the context of an average American diet may not produce maximal blood pressure reductions within a 4-week intervention period. This review provides further evidence of the benefit of sodium reduction for blood pressure lowering and gives insights into the subgroups of the population that may derive the greatest benefit from sodium reduction and the time course required to see benefit. Only three high-quality studies were identified during this 12-month review period, highlighting the critical need for more well-conducted rigorous studies in this area.

Effect of salt intake reduction on nocturia in patients with excessive salt intake

AIMS

To assess the efficacy of salt reduction for improving nocturia in patients with high salt intake.

METHODS

Changes in lower urinary symptoms and frequency volume chart by salt intake (men: 8 g/day; women: ≥7 g/day) were analyzed in this prospective study. Patients were instructed to use a brochure for salt intake restriction via interview once every four weeks. The daily salt intake was estimated by using spot urine samples.

RESULTS

Two-hundred twenty-three (69.5%) patients were successful in reducing their daily salt intake (S group), whereas 98 (30.5%) patients failed to reduce their salt intake (F group). In the S group, nocturia improved from 2.3 ± 0.9 to 1.4 ± 1.0, and nocturnal polyuria index (NPi) improved from 30.2 ± 7.5 to 27.7 ± 7.3% (P < 0.001). In the Core Lower Urinary Tract Symptom Score (CLSS) of the S group, Q3 (urgency) improved from 1.0 ± 1.0 to 0.9 ± 1.0 (P = 0.001); Q1 (diurnal frequency) (P < 0.001), and Q2 (nocturia) also improved (P < 0.001). Moreover, the quality of life parameter improved significantly (P < 0.001). The patients in the F group did not have improvements in any symptom during the study period.

CONCLUSIONS

Patients with nocturia who also have high salt intake should be advised to reduce their salt intake, as a lifestyle modification. Our results support the importance of randomized clinical trials with larger populations and the appropriate inclusion/exclusion criteria to conclude the clinical usefulness of salt reduction in this patient cohort.

Dietary intake habits and the prevalence of nocturia in Japanese patients with type 2 diabetes mellitus

AIMS/INTRODUCTION

No reports have been published on the association between dietary intake habits and nocturia in the diabetes population. We therefore evaluated this issue among Japanese patients with diabetes mellitus.

MATERIALS AND METHODS

Study participants in the present study were 785 Japanese patients with type 2 diabetes mellitus. Self-administered questionnaires were used to assess each type of dietary intake habit. Vegetable intake habit was assessed by the following question: "Do you have vegetables or seaweed every day?" We used the following two outcomes: (i) nocturia: ≥2 voids per night; and (ii) severe nocturia: ≥3 voids per night. Adjustment was made for age, sex, body mass index, glycated hemoglobin, hypertension, dyslipidemia, smoking, drinking, exercise habit, stroke, ischemic artery disease, diabetic nephropathy, diabetic neuropathy and diabetic retinopathy.

RESULTS

The prevalence of nocturia, severe nocturia, and vegetable intake habit was 39.9%, 14.4% and 67.3%, respectively. After adjusting for confounding factors, vegetable intake habit was independently inversely associated with nocturia and severe nocturia: the adjusted odds ratios were 0.67 (95% confidence interval [CI] 0.48-0.94) and 0.46 (95% CI 0.30-0.71), respectively. Among male patients, vegetable intake habit was independently inversely associated with severe nocturia, but not nocturia: the adjusted OR was 0.51 (95% CI 0.29-0.88). Among female patients, vegetable intake habit was independently inversely associated with nocturia and severe nocturia: the adjusted ORs were 0.44 (95% CI 0.24-0.79) and 0.34 (95% CI 0.15-0.78), respectively.

CONCLUSIONS

We found an inverse association between vegetable intake habit and nocturia in Japanese patients with type 2 diabetes mellitus.