Nocturia and Circadian Blood Pressure Profile in Healthy Elderly Male Volunteers

The effect of long-term COVID-19 on aetiological factors related to nocturia

AIMS AND OBJECTIVES

This study was conducted to examine the possible aetiology of nocturia in patients with long-term COVID-19.

BACKGROUND

Physical and neuropsychiatric symptoms, an increase in overactive bladder symptoms, especially from urinary system complaints, has been reported in patients with COVID-19, 10-14 weeks after the illness.

DESIGN

A descriptive design.

METHODS

The study consisted of 70 patients who had experienced COVID-19, had nocturia, and were followed in the State Hospital between April and July 2022. Data were collected using a patient information form, the 'TANGO' nocturia screening tool, and the Visual Analog Scale. This study was created in accordance with the STROBE Statement Checklist.

RESULTS

When the nocturia effects of long-term COVID-19 were examined it was determined that the urinary tract was the 'priority' aetiological condition. It was observed that there was a significant difference between the aetiological factor groups in terms of the mean age of the patients and the number of nocturia (p < .05). According to post-hoc analysis, the mean age of patients with a dominant cardio-metabolic factor was found to be significantly younger (p < .05). In addition, when comparing the number of nocturia according to the aetiological factors of the patients, it was observed that the number of nocturia was significantly frequent in the patients with a dominant sleep factor (p < .05).

CONCLUSIONS

It was found that the urinary tract aetiological factor was dominant in patients with long-term COVID-19 and nocturia, patients with a dominant cardiovascular aetiological factor were younger, and that the number of nocturia was higher in patients with a dominant sleep factor.

RELEVANCE TO CLINICAL PRACTICE

Identification of the early signs and symptoms and underlying causes of nocturia in individuals with post-COVID-19 syndrome will enable nurses and health professionals to guide the early identification of different underlying problems, as well as the implementation of approaches to treat and eliminate nocturia.

PATIENT OR PUBLIC CONTRIBUTION

The patients contributed to the study by agreeing to participate in the evaluation of nocturia complaints after COVID-19 infection.

Home Blood Pressure Monitoring And Nocturia In Adults

Although widely viewed as a urological condition, nocturia has been increasingly recognized to accompany various non-urological conditions such as hypertension and blood pressure (BP) elevation on office determination. Home BP monitoring (HBPM) has been shown superior to office-based readings and provides an opportunity to assess potential relationships between nocturia and novel indices derived from multiple BP recordings including BP load, BP variability, and arterial stiffness, which have prognostic significance. We retrospectively studied 103 home BP logs and nocturia frequencies provided by 61 stable cardiology patients ≥ 21 years without medication change. Nocturnal voids ranged from 0 to 5 voids per night, median: 1.5. Nocturia frequency was significantly correlated with home and office systolic BPs and with BP load, but not with diastolic BPs, BP variability or arterial stiffness. On Poisson regression analysis, the estimated prevalence ratio (PR) for home and office systolic BPs were 1.025 (CI: 1.01, 1.04; p < .001) and 1.01 (CI:1.00, 1.02; p = .019), indicating 2.5% and 1% increases in the risk of nocturia per mmHg increases in BP respectively. In conclusion, higher mean home and office systolic BPs are associated with self-reported nocturia frequency with stronger associations seen for home BP measurement. Nocturia frequency appears unrelated to mean home and office diastolic BPs. Nocturia may be related to BP load, (percentage of elevated BP values), but not to BP variability or arterial stiffness. Future prospective studies using HBPM are needed to confirm these findings and to contribute to the understanding of the elevated BP-nocturia link.

Circadian rhythms and renal pathophysiology

The reality of life in modern times is that our internal circadian rhythms are often out of alignment with the light/dark cycle of the external environment. This is known as circadian disruption, and a wealth of epidemiological evidence shows that it is associated with an increased risk for cardiovascular disease. Cardiovascular disease remains the top cause of death in the United States, and kidney disease in particular is a tremendous public health burden that contributes to cardiovascular deaths. There is an urgent need for new treatments for kidney disease; circadian rhythm-based therapies may be of potential benefit. The goal of this Review is to summarize the existing data that demonstrate a connection between circadian rhythm disruption and renal impairment in humans. Specifically, we will focus on chronic kidney disease, lupus nephritis, hypertension, and aging. Importantly, the relationship between circadian dysfunction and pathophysiology is thought to be bidirectional. Here we discuss the gaps in our knowledge of the mechanisms underlying circadian dysfunction in diseases of the kidney. Finally, we provide a brief overview of potential circadian rhythm-based interventions that could provide benefit in renal disease.

Implications of Cardiovascular Disease for Assessment and Treatment of Nocturia in Primary Care: Systematic Review and Nominal Group Technique Consensus

CONTEXT

Heart conditions affect salt and water homeostasis as a consequence of the underlying condition, compensatory processes, and therapy, and can result in nocturnal polyuria. These processes need to be identified as part of a full evaluation of nocturia.

OBJECTIVE

To conduct a systematic review of nocturia in cardiovascular disease and achieve expert consensus for primary care management. Primary care was defined as a health care setting in which the expertise did not include specialist cardiology.

EVIDENCE ACQUISITION

Four databases were searched from January 2000 to April 2020. A total of 3524 titles and abstracts were screened and 27 studies underwent full-text screening. Of these, eight studies were included in the analysis. The nominal group technique (NGT) was used to achieve consensus among an expert panel incorporating public involvement.

EVIDENCE SYNTHESIS

Most studies focused on nocturia related to blood pressure (BP), while one investigated leg oedema. Hypertension, particularly overnight blood pressure above normal, corresponds with higher risk of nocturia. NGT identified fluid and salt overload, nondipping hypertension, and some therapeutic interventions as key nocturia contributors. History taking and examination should identify raised jugular venous pressure/ankle swelling, with relevant investigations including measurement of BP, resting electrocardiogram, and B-type natriuretic peptide. Treatment recommends reducing salt (including substitutes), alcohol and caffeine. Heart failure is managed according to local guidance and controlling fluid intake to 1-2 l daily. If there is no fluid retention, reduce or discontinue diuretics or calcium channel blockers and follow up to reassess the condition. The target clinic blood pressure is 140/90 mm Hg.

CONCLUSIONS

Cardiovascular disease and its treatment are influential for understanding nocturia. Management aims to identify and treat heart failure and/or hypertension.

PATIENT SUMMARY

People with cardiovascular disease can suffer severe sleep disturbance because of a need to pass urine at night due to increased overnight blood pressure or heart failure. Following a detailed evaluation of the published research, a group of experts recommended practical approaches for assessing and treating these issues.

Diurnal rhythms of urine volume and electrolyte excretion in healthy young men under differing intensities of daytime light exposure

In humans, most renal functions, including urine volume and electrolyte excretions, have a circadian rhythm. Light is a strong circadian entrainment factor and daytime-light exposure is known to affect the circadian rhythm of rectal temperature (RT). The effects of daytime-light exposure on the diurnal rhythm of urinary excretion have yet to be clarified. The aim of this study was to clarify whether and how daytime exposure to bright-light affects urinary excretions. Twenty-one healthy men (21–27 years old) participated in a 4-day study involving daytime (08:00–18:00 h) exposure to two light conditions, Dim (< 50 lx) and Bright (~ 2500 lx), in a random order. During the experiment, RT was measured continuously. Urine samples were collected every 3 ~ 4 h. Compared to the Dim condition, under the Bright condition, the RT nadir time was 45 min earlier (p = 0.017) and sodium (Na), chloride (Cl), and uric acid (UA) excretion and urine volumes were greater (all p < 0.001), from 11:00 h to 13:00 h without a difference in total daily urine volume. The present results suggest that daytime bright light exposure can induce a phase shift advance in urine volume and urinary Na, Cl, and UA excretion rhythms.

Pharmacologic management of nocturnal polyuria: a contemporary assessment of efficacy, safety, and progress toward individualized treatment

This narrative review synthesizes current evidence on the medical management of nocturnal polyuria, including antidiuretic replacement therapy as well as other emerging modalities, with particular emphasis on areas of active investigation and future research directions. Relative to earlier formulations, the pharmacological profiles of novel desmopressin acetate nasal spray and orally disintegrating tablet formulations appear favorable in optimizing the balance between efficacy and safety. Additionally, several highly selective small-molecule arginine vasopressin 2 receptor agonists are under active development, while appropriately timed short-acting diuretics, pharmacotherapy for hypertension, nonsteroidal anti-inflammatory drugs, and sex hormone replacement therapy are also a focal point of extensive ongoing nocturnal polyuria research. Emerging laboratory technologies now make feasible a sub-stratification of nocturnal polyuria patients into substrate-based phenotypes for individualized treatment. An increasingly refined understanding of the pathogenesis of nocturnal polyuria, and arginine vasopressin dysregulation in particular, has also introduced new opportunities for point-of-care testing in patients with nocturnal polyuria.

Nocturia as an Unrecognized Symptom of Uncontrolled Hypertension in Black Men Aged 35 to 49 Years

Background

Hypertension is assumed to be asymptomatic. Yet, clinically significant nocturia (≥2 nightly voids) constitutes a putative symptom of uncontrolled hypertension. Black men with hypertension may be prone to nocturia because of blunted nocturnal blood pressure (BP) dipping, diuretic drug use for hypertension, and comorbidity that predisposes to nocturia. Here, we test the hypothesis that nocturia is a common and potentially reversible symptom of uncontrolled hypertension in black men.

Methods and Results

We determined the strength of association between nocturia (≥2 nightly voids) and high BP (≥135/85 mm Hg) by conducting in‐person health interviews and measuring BP with an automated monitor in a large community‐based sample of black men in their barbershops. Because nocturia is prevalent and steeply age‐dependent after age 50 years, we studied men aged 35 to 49 years. Among 1673 black men (mean age, 43±4 years [SD]), those with hypertension were 56% more likely than men with normotension to have nocturia after adjustment for diabetes mellitus and sleep apnea (adjusted odds ratio, 1.56; 95% CI, 1.25–1.94 [P<0.0001]). Nocturia prevalence varied by hypertension status, ranging from 24% in men with normotension to 49% in men whose hypertension was medically treated but uncontrolled. Men with untreated hypertension were 39% more likely than men with normotension to report nocturia (P=0.02), whereas men whose hypertension was treated and controlled were no more likely than men with normotension to report nocturia (P=0.69).

Conclusions

Uncontrolled hypertension was an independent determinant of clinically important nocturia in a large cross‐sectional community‐based study of non‐Hispanic black men aged 35 to 49 years.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unqiue identifier: NCT 02321618.

Relationship between nocturnal polyuria and non-dipping blood pressure in male patients with lower urinary tract symptoms

OBJECTIVE

The aim of the present study was to examine factors of nocturnal polyuria and blood pressure variability in male patients with lower urinary tract symptoms (LUTS) who were treated.

METHODS

Two hundred and forty-two male patients with LUTS who were treated recorded frequency volume charts. We investigated their urinary condition and characteristics, medical history, and medications. Thirty-four of these patients underwent ambulatory blood pressure monitoring (ABPM) for 24 hours to evaluate blood pressure variability.

RESULTS

In the present study, 194 patients (80.2%) had nocturia and 136 (56.2%) had nocturnal polyuria (NP). Among patients with nocturia (≥2 voids/night), 130 (67.0%) had nocturnal polyuria, and 26 of those with nocturia (13.4%) had reduced functional bladder capacity. The use of 2 or more antihypertensive medications was significantly higher in the NP than non-NP group (22.8% vs. 12.3%; P = .035). Significantly more patients in the NP group had non-dipping blood pressure (P = .037). Non-dipping blood pressure was considered a potential factor for NP.

CONCLUSION

We suggest that treatment of non-dipping blood pressure may improve NP.

The effect of antidiuretic hormone on urine and serum electrolyte levelsin children with primary monosymptomatic nocturnal enuresis

Background/aim: The data concerning the effects of desmopressin on water/electrolyte disturbances of children with primary monosymptomatic nocturnal enuresis (PMNE) are limited. In the present study we aimed to evaluate the effect and tolerability of desmopressin on blood and urine electrolytes and osmolality in PMNE.Materials and methods: Thirty-five children with PMNE between the ages of 5 and 15 participated in the study. Patients collected urine during the daytime and acknowledged the night time fluid restriction before starting to use the desmopressin tablets. The medication was taken orally at least 1 h before bedtime. Blood and urine samples were collected before the introduction of the treatment (day 0) and on the third and seventh days of the administration of desmopressin to determine osmolality and electrolyte levels.Results: Thirty-five patients participated in the study. Twenty-one patients (60%) were male and 14 (40%) were female. The mean age was 9.6 - 2.7 years. There were no significant changes in serum osmolality, urine osmolality, and serum sodium concentration. Mean urine calcium/creatinine ratio was 0.03 - 0.01 mg/mg at the beginning, 0.06 - 0.02 mg/mg on the third day, and 0.04 - 0.01 mg/mg on the seventh day of the study. No significant changes were seen in urine calcium/creatinine ratio before and after treatment.Conclusion: Desmopressin appeared to be a well-tolerated drug and provided a safe and effective treatment for children who were following fluid intake restriction for PMNE.

Renal physiology of nocturia

Renal function, diurnal fluctuations in arginine vasopressin (AVP) secretion, sex, and advanced age affect urine formation and may contribute to nocturia. Renal effects of AVP are mediated by AVP V2 receptors in the kidney collecting duct. Changes in AVP concentration have the greatest relative effects on urine volume when AVP levels are low; therefore small changes can have a large effect on renal water excretion. AVP is the major regulator of water excretion by the kidneys, and AVP levels have been shown to affect nocturnal voiding. Results of several studies show that patients with nocturia had no significant variation in plasma AVP, whereas patients without nocturia had significant diurnal variation in plasma AVP. The V2 receptor gene is located on the X chromosome, which has important sex-specific consequences. For example, mutations in the V2 gene can cause nephrogenic diabetes insipidus, predominantly in men. Age-related changes in water metabolism are associated with overall body composition, kidney, and brain. Older people generally experience decreased extracellular fluid and plasma volume, which leads to increased adverse consequences from net body water gain or loss. Renal function declines with age, and the ability to concentrate urine and conserve sodium is reduced in the elderly. Thirst perception is also decreased in the elderly, who, compared with younger people, tend to hypersecrete AVP in response to higher plasma osmolality, possibly resulting in hyponatremia. These aspects of renal physiology should be considered when antidiuretic drugs are prescribed for the treatment of nocturia.

Urinary concentration does not exclusively rely on plasma vasopressin. A study between genders. Gender and diurnal urine regulation

AIM

We investigated the influence of gender on the diurnal regulation of urine production with special focus on vasopressin, oxytocin and prostaglandin E2.

METHODS

Fifteen young women in mid-follicular phase and 22 young men (20-33 years) were included. All participants underwent a 24-h circadian inpatient study under standardized conditions for measurements of plasma vasopressin, oxytocin, sodium and osmolality. Urine was fractionally collected for measurements of electrolytes, aquaporin-2 and prostaglandin E2.

RESULTS

Plasma vasopressin expressed a diurnal rhythm with a night-time increase in both genders (P < 0.001). The ratio between mean daytime and mean night-time was 1.57 [95% CI: 1.33-1.84] P < 0.001 in men and 1.35 [95% CI: 1.11-1.64] P = 0.002 in women. P-vasopressin was higher in males during the night (P < 0.05). There was no difference in diuresis (P = 0.43), urine osmolality (P = 0.12) or aquaporin-2 excretion (P = 0.80) between genders. We found a trend towards a higher reabsorption of free water in males (P = 0.07). The excretion of prostaglandin E2 was higher in males (P < 0.001). There was no diurnal rhythm in p-oxytocin (P = 0.37) and no correlation to diuresis, urine osmolality or aquaporin-2 excretions.

CONCLUSION

Similar urinary flows and osmolalities are associated with levels of plasma vasopressin and renal PGE2, which are higher in males than in females. Oxytocin does not seem to play a role in the diurnal urine formation, whereas prostaglandin E2 could represent a mediator of the gender difference, not only as a mediator of the vasopressin response, but also as an independent factor. These findings need further elucidation.

Relationship of circadian pattern of urine sodium excretion to hypertension and obstructive sleep apnoea

OBJECTIVES

Obstructive sleep apnoea (OSA) and hypertension frequently coexist, and both are associated with higher night-time than daytime urine sodium excretion rate (UNaV). However, the relative contribution of each condition is unknown. We compared the circadian pattern of UNaV in hypertensive and normotensive patients with and without OSA.

METHODS

Hypertensive [blood pressure (BP) >140/90 or on antihypertensive medications, excluding diuretics] and normotensive (BP <135/85) patients underwent overnight polysomnography to determine the presence or absence of OSA (apnoea-hypopnoea index ≥10 or <10, respectively), same-day 24-h urine collection divided into day and night-time samples and automated evening BP measurement.

RESULTS

Twenty-six hypertensive (9 without and 17 with OSA) and 26 normotensive (15 without and 11 with OSA) patients were studied. Night-time UNaV was higher in the hypertensive than the normotensive patients. Whereas in the normotensive patients night-time UNaV was unaffected by OSA, in the hypertensive patients, it was higher in those with than without OSA (P = 0.009 for OSA × hypertension interaction). Night : day UNaV ratio was higher in hypertensive than normotensive patients, but was not significantly affected by OSA in either group. On multivariate analysis, SBP and apnoea-hypopnoea index were independent predictors of night-time UNaV (model r = 0.574, P < 0.001) and night : day UNaV ratio (model r = 0.397, P < 0.001). However, SBP was the strongest independent predictor.

CONCLUSIONS

In hypertensive patients, OSA exacerbates the reversal of the normal circadian sodium excretion pattern by elevating nocturnal UNaV, possibly via its BP-elevating effects. However, OSA does not affect nocturnal UNaV in normotensive patients.

Nocturnal polyuria and decreased serum testosterone: is there an association in men with lower urinary tract symptoms?

OBJECTIVES

To investigate the putative association between nocturia and decreased serum testosterone in men with lower urinary tract symptoms.

METHODS

Frequency volume charts and serum testosterone levels of patients visiting the outpatient clinic for lower urinary tract symptoms were collected and analyzed. Age, prostate volume, body mass index and the presence of comorbidities were accounted for. Frequency volume charts were analyzed for pathophysiological components of nocturnal polyuria, global polyuria, decreased nocturnal bladder capacity and increased frequency to identify associated risks. Frequency volume charts were also used to chart 8-h changes of volume, frequency and capacity to identify time diurnal interactions with risk factors based on serum testosterone levels.

RESULTS

A total of 2180 patients were enrolled in the study. Multivariate analysis showed testosterone decreased 0.142 ng/mL for every increase in nocturia, independent of other factors. Logistic regression analysis showed a significant difference between pathophysiological components. Decreased testosterone was shown to carry a significant independent risk for overall nocturia (odds ratio 1.60, 95% confidence interval 1.013-2.527, P = 0.044), and particularly nocturnal polyuria (odds ratio 1.934, 95% confidence interval 1.001-3.737, P = 0.027). Repeated measurement models showed patients with serum testosterone below 2.50 ng/mL to have a paradoxical increase in nocturnal urine volume at night.

CONCLUSIONS

Nocturia, especially nocturnal polyuria, is associated with decreased serum testosterone. Patients with low serum testosterone show increased nocturnal urine output.

Non-dipping phenomenon in children with monosymptomatic nocturnal enuresis

PURPOSE

Monosymptomatic nocturnal enuresis is a common disorder seen in childhood, and many factors play a role in its etiopathology to varying degrees. The aim of our study was to investigate the possible association between nocturnal enuresis and 24-h blood pressure profiles of enuretic children.

METHODS

A total of 45 children ranging in age from 6 to 15 years with monosymptomatic nocturnal enuresis and 22 age-matched healthy controls were enrolled in our study. The blood pressure measurement was made at 30-min intervals during a 24-h period via an ambulatory blood pressure measurement device. Both groups underwent medical tests that included a complete blood count, blood biochemistry profile, urinalysis and blood renin-aldosterone levels, and all study subjects received an abdominal ultrasound.

RESULTS

Statistically significant high nocturnal blood pressure levels were observed in our patients with monosymptomatic nocturnal enuresis compared with the control group (p < 0.05). The mean values of the day-to-night difference (dipping) in the systolic and diastolic blood pressure of the patients were significantly lower than those of control group (p < 0.05).

CONCLUSION

Nocturnal enuresis should not only be accepted as a urinary system disorder. Possible systemic causative factors have to be examined, especially in patients that are resistant to first-line therapy. Based on the results of our study, we deduce that one of the factors that plays a role in the pathogenesis of enuresis nocturna is a non-dipping blood pressure profile (the "non-dipping" phenomenon).

Gender difference in efficacy and dose response in Japanese patients with nocturia treated with four different doses of desmopressin orally disintegrating tablet in a randomized, placebo-controlled trial

WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Desmopressin orally disintegrating tablet (ODT) 60-240 μg has proved an effective and well-tolerated antidiuretic treatment in male and female patients with nocturia. The main adverse event is hyponatraemia. Recent studies suggest that female patients are more sensitive to desmopressin ODT, achieving the same efficacy at lower doses than male patients. The study demonstrates the efficacy of desmopressin ODT in male and female Japanese patients with nocturia. It provides further evidence that the optimum desmopressin dose for the treatment of nocturia is lower in females than in males. Tailoring the dose according to gender provides an improved therapeutic window with the benefits of a decreased risk of hyponatraemia without compromising efficacy.

OBJECTIVES

To establish the dose-response efficacy of desmopressin in a Japanese patient population for the treatment of nocturia. To explore gender differences in sensitivity to desmopressin in Japanese patients with nocturia.

PATIENTS AND METHODS

A phase II multicentre, randomized, placebo-controlled, double-blind, parallel-group, comparative clinical trial was conducted. Subjects aged 55-75 years, with a mean of ≥2 voids per night, were included and randomized to receive placebo or one of four doses of desmopressin orally disintegrating tablet (ODT): 10 μg, 25 μg, 50 μg or 100 μg. The dose-response relationship of pharmacodynamic variables measured after a single dose of desmopressin administered to water-loaded subjects (treatment period 1) was compared with the primary clinical endpoint of change from baseline in mean number of nocturnal voids, after 28 days of desmopressin treatment (treatment period 2).

RESULTS

A total of 116 patients were treated in treatment period 1 of whom 113 qualified for treatment period 2, and 111 completed the study. In treatment period 1 a dose-response relationship was observed, both overall and in each gender group. Overall, the duration of antidiuretic action (DOA; time with urine osmolality >200 mOsm/kg) for the 25, 50 and 100 μg doses was 2 h (P = 0.010), 3.45 h (P < 0.001) and 5.74 h (P < 0.001), respectively; all statistically significant compared with placebo. Female patients were found to be more sensitive to desmopressin; DOA in female patients was longer than in male patients after desmopressin 25 and 50 μg. Extrapolation suggests that male patients require ∼58 μg to achieve similar DOA to females receiving 25 μg. A dose-response relationship was also seen in treatment period 2 for the group overall with a greater reduction in mean number of nocturnal voids from baseline to day 28 at higher doses, and with significant reductions in the 25- (P = 0.015) 50- (P < 0.001) and 100-μg (P = 0.001) dose groups compared with placebo. Similar dose-response relationships were also seen when the data were analysed by gender. Desmopressin ODT was well tolerated with no serious or severe adverse events.

CONCLUSIONS

A dose-response relationship for desmopressin ODT was shown in a population of Japanese patients with nocturia. The study suggests that the optimum desmopressin dose for the treatment of nocturia is lower in females than in males, indicating a gender-specific therapeutic window with a decreased risk of hyponatraemia without compromising efficacy on reduction of nocturnal voids. Further dose-finding studies are planned to confirm the recommended dose for the treatment of nocturia in a Japanese patient population.

Efficacy of Ramelteon in Patients with Insomnia and Nocturia

OBJECTIVES

To study the efficacy of ramelteon for patients with insomnia and nocturia.

METHODS

Forty-nine patients experiencing insomnia and two or more nocturnal voids were included. The degree of lower urinary tract symptoms and sleep disorders was evaluated using the International Prostate Symptom Score (IPSS), Pittsburg Sleep Quality Index (PSQI)(1) score, and frequency/volume chart (FVC). The patients were treated with ramelteon (8 mg) for four weeks and then reexamined by questionnaire and FVC to evaluate the therapeutic efficacies.

RESULTS

The mean IPSS score was 16.1 ± 6.9 at baseline and 12.4 ± 7.1 at four weeks. The subject scores for the number of nocturnal voids also decreased significantly from 3.3 ± 0.9 to 2.9 ± 1.0. In addition, PSQI scores improved significantly from 7.4 ± 2.9 to 5.4 ± 2.8. According to the FVC, the number of nocturnal voids decreased significantly from 3.1 ± 1.2 at baseline to 2.2 ± 1.1 at four weeks, and nighttime bladder capacity improved significantly from 181.4 ± 79.9 to 201.1 ± 93.7 mL.

CONCLUSION

Ramelteon alleviated nocturia and disturbed sleep in patients with insomnia and nocturia and led to increased nighttime bladder capacity.

Reduced anti-diuretic response to desmopressin during wet nights in patients with monosymptomatic nocturnal enuresis

OBJECTIVE

To investigate why not all children with monosymptomatic nocturnal enuresis (MNE) treated with desmopressin give an adequate response.

MATERIALS AND METHODS

We included 114 children with MNE aged 5-15 years (9.8 ± 0.2 years) who experienced at least 1 wet night and more than 2 dry nights during desmopressin treatment. The patients made home recordings for 2 weeks as baseline and for 2-4 weeks of desmopressin titration. Nocturnal urine production during wet and dry nights, and maximum voided volumes (MVVs) were documented in all patients.

RESULTS

Sixty-four patients were desmopressin non-responders, 29 were either partial responders or responders, while 21 patients were full responders. Desmopressin reduced nocturnal urine production dramatically during dry nights compared with pre-treatment wet nights. Nocturnal urine production during desmopressin treatment was significantly greater during wet nights compared to dry nights (243 ± 9.32 vs 176 ± 5.31 ml, P < 0.001). There was a highly significant correlation between individual nocturnal urine output and MVV, and dry nights were characterized by nocturnal urine output/MVV ratios well below 1.0.

CONCLUSION

The anti-enuretic response to desmopressin seems to be dependent upon the degree of reduction in nocturnal urine production. Research on desmopressin bioavailability in children is needed.

Sleep deprivation induces excess diuresis and natriuresis in healthy children

Urine production is reduced at night, allowing undisturbed sleep. This study was undertaken to show the effect of sleep deprivation (SD) on urine production in healthy children. Special focus was on gender and children at an age where enuresis is still prominent. Twenty healthy children (10 girls) underwent two 24-h studies, randomly assigned to either sleep or SD on the first study night. Diet and fluid intake were standardized. Blood samples were drawn every 4 h during daytime and every 2 h at night. Urine was fractionally collected. Blood pressure and heart rate were noninvasively monitored. Blood was analyzed for plasma antidiuretic hormone (AVP), atrial natriuretic peptide (ANP), angiotensin II, aldosterone, and renin. Urine was analyzed for aquaporin-2 and PGE2. Successful SD was achieved in all participants with a minimum of 4 h 50 min, and full-night SD was obtained in 50% of the participants. During SD, both boys and girls produced markedly larger amounts of urine than during normal sleep (477 ± 145 vs. 291 ± 86 ml, P < 0.01). SD increased urinary excretion of sodium (0.17 ± 0.05 vs. 0.10 ± 0.03 mmol·kg−1·h−1) whereas solute-free water reabsorption remained unchanged. SD induced a significant fall in nighttime plasma AVP ( P < 0.01), renin ( P < 0.05), angiotensin II ( P < 0.001), and aldosterone ( P < 0.05) whereas plasma ANP levels remained uninfluenced ( P = 0.807). Nighttime blood pressure and heart rate were significantly higher during SD (mean arterial pressure: 78.5 ± 8.0 vs. 74.7 ± 8.7 mmHg, P < 0.001). SD leads to natriuresis and excess diuresis in healthy children. The underlying mechanism could be a reduced nighttime dip in blood pressure and a decrease in renin-angiotensin-aldosterone system levels during sleep deprivation.

Circadian rhythms in urinary functions: possible roles of circadian clocks?

Circadian clocks are the endogenous oscillators that harmonize a variety of physiological processes within the body. Although many urinary functions exhibit clear daily or circadian variation in diurnal humans and nocturnal rodents, the precise mechanisms of these variations are as yet unclear. In this review, we briefly introduce circadian clocks and their organization in mammals. We then summarize known daily or circadian variations in urinary function. Importantly, recent findings by others as well as results obtained by us suggest an active role of circadian clock genes in various urinary functions. Finally, we discuss possible research avenues for the circadian control of urinary function.

Computational simulation of vasopressin secretion using a rat model of the water and electrolyte homeostasis

Background

In mammals, vasopressin (AVP) is released from magnocellular neurons of the hypothalamus when osmotic pressure exceeds a fixed set-point. AVP participates to the hydromineral homeostasis (HH) by controlling water excretion at the level of the kidneys. Our current understanding of the HH and AVP secretion is the result of a vast amount of data collected over the five past decades. This experimental data was collected using a number of systems under different conditions, giving a fragmented view of the components involved in HH.

Results

Here, we present a high-level model of the rat HH based on selected published results to predict short-term (hours) to long-term (days) variation of six major homeostatic parameters: (1) the extracellular sodium concentration, (2) the AVP concentration, (3) the intracellular volume, (4) the extracellular volume, (5) the urine volume and (6) the water intake. The simulation generates quantitative predictions like the daily mean of the extracellular sodium concentration (142.2 mmol/L), the AVP concentration, (1.7 pg/ml), the intracellular volume (45.3 ml/100 g body weight - bw), the extracellular volume (22.6 ml/100 g bw), the urine volume (11.8 ml/100 g bw) and the cumulative water intake (18 ml/100 g bw). The simulation also computes the dynamics of all these parameters with a high temporal resolution of one minute. This high resolution predicts the circadian fluctuation of the AVP secretion (5 ± 2 pg/ml) and defines the limits of a restoration and a maintenance phase in the HH (2.1 pg/ml). Moreover, the simulation can predict the action of pharmacological compounds that disrupt the HH. As an example, we tested the action of a diuretic (furosemide) combined with a sodium deficient diet to generate quantitative prediction on the extracellular sodium concentration (134 mmol/L) and the need-induced water intake (20.3 ml/100 g bw). These simulated data are compatible with experimental data (136 ± 3 mmol/L and 17.5 ± 3.5 ml/100 g bw, respectively).

Conclusion

The quantitative agreement of the predictions with published experimental data indicates that our simplified model of the HH integrates most of the essential systems to predict realistic physiological values and dynamics under a set of normal and perturbed hydromineral conditions.

Excess diuresis and natriuresis during acute sleep deprivation in healthy adults

The transition from wakefulness to sleep is associated with a pronounced decline in diuresis, a necessary physiological process that allows uninterrupted sleep. The aim of this study was to assess the effect of acute sleep deprivation (SD) on urine output and renal water, sodium, and solute handling in healthy young volunteers. Twenty young adults (10 male) were recruited for two 24-h studies under standardized dietary conditions. During one of the two admissions, subjects were deprived of sleep. Urine output, electrolyte excretions, and osmolar excretions were calculated. Activated renin, angiotensin II, aldosterone, arginine vasopressin, and atrial natriuretic peptide were measured in plasma, whereas prostaglandin E2 and melatonin were measured in urine. SD markedly increased the diuresis and led to excess renal sodium excretion. The effect was more pronounced in men who shared significantly higher diuresis levels during SD compared with women. Renal water handling and arginine vasopressin levels remained unaltered during SD, but the circadian rhythm of the hormones of the renin-angiotensin-aldosterone system was significantly affected. Urinary melatonin and prostaglandin E2 excretion levels were comparable between SD and baseline night. Hemodynamic changes were characterized by the attenuation of nocturnal blood pressure dipping and an increase in creatinine clearance. Acute deprivation of sleep induces natriuresis and osmotic diuresis, leading to excess nocturnal urine production, especially in men. Hemodynamic changes during SD may, through renal and hormonal processes, be responsible for these observations. Sleep architecture disturbances should be considered in clinical settings with nocturnal polyuria such as enuresis in children and nocturia in adults.

Sleep-disordered breathing and 24-hour blood pressure pattern among older adults

BACKGROUND

To examine the association between sleep-disordered breathing (SDB) and 24-hour blood pressure (BP) pattern among community-dwelling older adults.

METHODS

A convenience sample of 70 community-dwelling older adults, recruited from senior housing, community centers, and learning centers, were admitted to General Clinical Research Center, Emory University Hospital, Atlanta, Ga. Information regarding demographic and clinical history was obtained using questionnaires. Twenty-four-hour BP monitoring in supine position was performed using Spacelabs model 20207. Breathing during sleep was monitored with the use of a modified sleep recording system (Embletta, PDS), which monitors nasal and oral airflow, chest and abdominal movements, and pulse oximetry. Night time-daytime (night-day) BP ratio (average night-time BP divided by daytime BP) was calculated both for systolic and diastolic BPs.

RESULTS

Sixty-nine participants, mean age 74.9 +/- 6.4 years (41 [57%] women), completed the study. The mean apnea-hypopnea index (AHI) was 13 +/- 13 per hour of sleep, and 20 participants (29%) had AHI > or =15 per hour of sleep, indicating moderate to severe SDB. Moderate to severe SDB (AHI > or =15 per hour of sleep) was significantly associated with nocturnal hypertension, whereas there was no statistically significant difference in wake-time BP between those with and without moderate to severe SDB. Stepwise multiple regressions showed that AHI independently predicted increased night-day systolic and night-day diastolic BP ratio, even after controlling for nocturia frequency.

CONCLUSIONS

The results indicate increased BP load associated with increased AHI in this group of older adults. This increased BP load may contribute to increased hypertension-related morbidity and disease burden.