Renal physiology of nocturia

The role of renal circadian biorhythms in lifelong LUTS

INTRODUCTION

This article delves into the intricate relationship between kidney function, diuresis, and lower urinary tract symptoms (LUTS) throughout the transitions of the human lifespan. It explores circadian regulation of urine production, maturation of renal function from birth to adulthood, and effects of aging on kidney function and LUTS. The complex connections between these factors are highlighted, offering insights into potential interventions and personalized management strategies.

METHODS

An international panel of seven experts engaged in online discussions, focusing on kidney function, diuresis, and LUTS throughout life. This manuscript summarizes expert insights, literature reviews, and findings presented during a webinar and subsequent discussions.

RESULTS

Renal function undergoes significant maturation from birth to adulthood, with changes in glomerular filtration rate, diuresis, and tubular function. A circadian rhythm in urine production is established during childhood. Adolescents and young adults can experience persistent enuresis due to lifestyle factors, comorbidities, and complex physiological changes. In older adults, age-related alterations in kidney function disrupt the circadian rhythm of diuresis, contributing to nocturnal polyuria and LUTS.

CONCLUSION

The interplay between kidney function, diuresis, and LUTS is crucial in understanding lifelong urinary health. Bridging the gap between pediatric and adult care is essential to address enuresis in adolescents and young adults effectively. For older adults, recognizing the impact of aging on renal function and fluid balance is vital in managing nocturia. This holistic approach provides a foundation for developing innovative interventions and personalized treatments to enhance quality of life for individuals with LUTS across all stages of life.

Association of nocturia of self-report with estimated glomerular filtration rate: a cross-sectional study from the NHANES 2005-2018

Nocturia is a manifestation of systemic diseases, in which chronic kidney disease (CKD) is an independent predictor of nocturia due to its osmotic diuretic mechanism. However, to our knowledge, previous studies have not examined the association between nocturia and estimated glomerular filtration rate (eGFR). The purpose of this study was to assess the association between nocturia exposure and eGFR in the general US population. This study presents a cross-sectional analysis of the general US population enrolled in the National Health and Nutrition Examination Survey (NHANES) from 2005 to 2018. To account for potential confounding factors, linear regression analysis was conducted to investigate the association between nocturia and eGFR. Stratified analyses and interaction tests were employed to examine the variables of interest. Additionally, sensitivity analyses were conducted across diverse populations. A total of 12,265 individuals were included in the study. After controlling for confounding factors, the results of the linear regression analysis indicated that a single increase in nocturnal voiding frequency was associated with a decrease in eGFR by 2.0 mL/min/1.73 m2. In comparison to individuals with a nocturnal urinary frequency of 0, those who voided 1, 2, 3, 4, and ≥ 5 times at night experienced a decrease in eGFR by 3.1, 5.4, 6.4, 8.6 and 4.0 mL/min/1.73 m2, respectively. Nocturia was found to be associated with a decreased eGFR of 4 mL/min/1.73 m2 when compared to individuals without nocturia. The sensitivity analysis yielded consistent findings regarding the association between nocturia and eGFR in both CKD and non-CKD populations, as well as in hypertensive and non-hypertensive populations. Nevertheless, inconsistent conclusions were observed across various prognostic risk populations within the CKD context. The presence of nocturia and heightened frequency of nocturnal urination have been found to be associated with a decline in eGFR.

Laying the foundation for enhancing safety of desmopressin in older people: Validation of capillary blood sodium levels

PURPOSE

We aim to make desmopressin a safe treatment option for (older) patients at risk for hyponatremia, by introducing a new way of sodium monitoring. The goal is to reduce the risk of hyponatremia, enhance patient safety and ultimately introduce self-monitoring of sodium levels. The first step in the aforementioned is to validate capillary sodium.

MATERIALS AND METHODS

100 randomly selected patients admitted to the urology department received a single finger prick to collect capillary blood (250 µl) in a lithium-heparin tube. Each patient acted as its own control for the capillary and venous blood sample. Venous and capillary plasma sodium were analyzed by indirect ion-selective electrode measurement. The primary outcome was the agreement between capillary and venous sodium measurements, measured by the intra-class correlation coefficient (ICC).

RESULTS

One hundred paired blood samples were obtained of which four were excluded. There was no significant statistical difference observed between venous and capillary sodium (-0.23 mmol/L, p = 0.374). The ICC for single measures between capillary and venous sodium was 0.82 (95% confidence interval 0.75-0.88). Inter-method differences analyzed by a Bland-Altman plot and a Passing-Bablock regression did not reveal a statistically significant difference between both groups.

CONCLUSIONS

We demonstrated that venous and capillary sodium levels are interchangeable, taken into account the inter- and intravariability between analyses. We provided the first step towards a simple and safe solution for frequent sodium monitoring through a minimal invasive capillary blood collection. The results are of direct clinical relevance to safely use desmopressin in (older) patients at risk.

Efficacy and safety of desmopressin on frequency and urgency in female patients with overactive bladder and nocturia, current clinical features and outcomes: A systematic review

Objective

Methods

Results

Conclusion

First voided volume: A novel approach to characterize nocturia

AIMS

Nocturnal polyuria syndrome (NPS) denotes nocturnal polyuria (NP) in the absence of identifiable contributory factors. The trajectory of nocturnal urine production (NUP; typically expressed as ml/hour) may be useful in delineating between NP patients with versus without NPS, but changes in absolute urine volume, the directly measured substrate for behavioral and pharmacologic interventions targeting nocturnal urine production, have not been well characterized. This study compares the ratio of the first nocturnal voided volume (FNVV) to the nocturnal average voided volume (NAVV) in patients with versus without NPS.

METHODS

Secondary analysis of 24-h voiding diaries from male patients greater than or equal to 18 years of age with two or more nocturnal voids and NP using two different criteria for NP: NUP greater than or equal to 90 ml/h and nocturnal polyuria index (NPi) greater than or equal to 0.33. Patients with diabetes insipidus and CPAP-adherent obstructive sleep apnea (OSA) were excluded. Patients were divided into 2 groups: secondary NP (OSA, congestive heart failure, and chronic kidney disease) and NPS (absence of edema, diuretic use, and the aforementioned comorbidities). FNVV was defined as the volume of urine accompanying the first nocturic episode. NAVV was defined as nocturnal urine volume/(number of nocturnal voids + 1). The nocturnal urine trajectory ratio (NUTR) was defined as FNVV/NAVV.

RESULTS

At NUP greater than or equal to 90 ml/h, NUTR was significantly greater in patients with (n = 73) versus without (n = 28) NPS (1.10 [0.89-1.33] vs. 0.91 [0.55-1.15], p = .012). At NPi greater than or equal to 0.33, NUTR was likewise significantly greater in patients with (n = 92) versus without (n = 32) NPS (1.09 [0.90-1.33] vs. 0.91 [0.57-1.17], p = .010).

CONCLUSIONS

The volume of urine produced in the early hours of sleep is central to identification of NPS in patients with nocturia.

Nocturia through the menopausal transition and beyond: a narrative review

INTRODUCTION AND HYPOTHESIS

Nocturia, defined as the act of waking to pass urine during sleeping, is a common problem in older women and is associated with significant morbidity and impairments in health-related quality of life. The aim of this review was to synthesize the current evidence regarding the incidence, impact, pathophysiology, and specific diagnostic approach of nocturia in the postmenopausal population.

METHODS

We searched PubMed and Web of Science databases to identify relevant studies published through June 2020. Reference lists of the reviews obtained were screened for other articles deemed pertinent by the authors.

RESULTS

Genitourinary symptoms attributed to the menopause have been reported to occur in nearly 90% of postmenopausal women, and nocturia is one of the most common. The relative deficiency in endogenous estrogen production after the menopause is thought to exacerbate all major pathophysiological mechanisms that may underlie nocturia, including reduced bladder capacity, nocturnal polyuria, global polyuria, and sleep disorders. Diminished estrogen may induce anatomical and physiological bladder changes, contributing to a reduction in functional bladder capacity. Excess nocturnal urine production can also be provoked by estrogen depletion, either via free water-predominant diuresis by an impaired secretion of antidiuretic hormone, or a salt-predominant diuresis owing to diminished activation of the renin-angiotensin-aldosterone axis. Additionally, a relationship between the transition to menopause and impaired sleep has been described, mediated by increased incidence in vasomotor symptoms and obstructive sleep apnea signs during the menopause.

CONCLUSION

Further research is necessary to better characterize and manage nocturia in postmenopausal women.

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.

Phenotyping nocturnal polyuria: circadian and age-related variations in diuresis rate, free water clearance and sodium clearance

BACKGROUND

this study compares diuresis rate, sodium clearance and free water clearance (FWC) by age and time of day (nighttime vs. daytime) in subjects with and without nocturnal polyuria (NP) to determine whether these variables affect the phenotype of NP.

METHODS

post hoc analysis of two prospective observational studies. Eight urine samples collected at 3-h intervals and a single blood sample were used to calculate daytime (10a/1p/4p/7p/10p) and nighttime (1a/4a/7a) diuresis rates, sodium clearance and FWC. Three mixed linear models were constructed for diuresis rate, sodium clearance and FWC using four predictor variables: NP status (present [nocturnal urine production >90 ml/h] vs. absent [≤90 ml/h]), time of day, age and study identification.

RESULTS

subjects with NP experienced higher nighttime versus daytime diuresis rates, sodium clearance and FWC. Regardless of NP status, increased age was accompanied by an increase in the ratio of nighttime/daytime diuresis rate, nighttime sodium clearance and daytime sodium clearance. FWC showed a complex age effect, which was independent of time of day or NP status.

CONCLUSIONS

age-related increases in nighttime/daytime diuresis rate, 24-h sodium clearance and 24-h FWC are not specific to subjects with NP. The age-related surge in either nocturnal sodium clearance or nocturnal FWC may represent the relevant substrate for behavioural or pharmacologic interventions targeting sodium diuresis or free water diuresis, respectively. Increases in FWC in older age groups may reflect impaired circadian rhythmicity of endogenous AVP or changes in responsiveness of the aged nephron to water clearance.

Nocturnal polyuria: Literature review of definition, pathophysiology, investigations and treatment

Nocturnal polyuria (NP) is characterised by increased urine production overnight in comparison to daytime. It has significant adverse events in adults including reduced quality of life, increased risk of falls and increased mortality.

Although NP can be a manifestation of other significant conditions like heart failure and sleep apnoea, there are lots of unanswered questions about NP. What is the underlying pathophysiology? Is NP a physiological manifestation of ageing? Is the circadian change of vasopressin release the primary pathology? Or is it a secondary phenomenon to a low diurnal production of urine? Is the primary pathology at the kidney level or is there another humoral, cardiac, or endovascular element? In this article, we summarise the available English-language literature on the subject of NP, including its epidemiology, pathogenesis, diagnosis and treatment.

Level of evidence: Not applicable for this multicentre audit.

Pharmacotherapy for Nocturia

Purpose of Review

To assess current pharmacological principles used for treatment of nocturia/nocturnal polyuria.

Recent Findings

The pathophysiology of nocturia is often multifactorial, but two main mechanisms have been identified, occurring alone or in combination: low functional bladder capacity and nocturnal polyuria. The multifactorial pathophysiology not only implies several possible targets for therapeutic intervention but also means that it is unlikely that one treatment modality including drugs will be successful in all patients. Drugs approved for the treatment of male LUTS and male and female OAB are known to be far more effective for treatment of the daytime symptoms than for nocturia.

Summary

Several pharmacological principles have been tested with varying success. The treatment of choice should depend upon the main underlying cause, thus aiming primarily to increase bladder capacity by counteracting detrusor overactivity and/or reducing nocturnal polyuria. Using current available agents, effective, personalized treatment should be designed taking into account gender, co-morbidities, and identified etiological factors. However, there is a medical need for new, approved drugs for treatments for patients with nocturia.

Nocturia: aetiology and treatment in adults

Nocturia is an extremely common condition that has major sequelae for affected patients. Through disruption of sleep, nocturia impairs quality of life and worsens health outcomes, and is associated with a variety of morbidities including diabetes, coronary artery disease, obstructive sleep apnoea, obesity, metabolic syndrome, and depression. Unsurprisingly, several studies have also linked nocturia with reduced survival. Nocturia is not simply a consequence of lower urinary tract disease; rather, it is a multifactorial disorder that is often a manifestation of an underlying renal or systemic disease. Through the use of the frequency volume chart, clinicians can accurately quantify nocturia and determine its aetiology. Evaluation of quality of life and sleep using simple measures is essential in order to assess the impact of nocturia on a patient. Numerous treatment options for nocturia exist, but most are associated with minor benefit or lack sufficient evidence supporting their use. By systematically analysing an individual's causes of nocturia, clinicians can design appropriate treatment strategies to most effectively treat this condition.

Pharmacokinetics and Pharmacodynamics of the Oral Disintegrating Tablet of Desmopressin in Adults with Nocturnal Polyuria: A Pilot Study

INTRODUCTION

The higher sensitivity to desmopressin (dDAVP) found in women and older patients with nocturnal polyuria (NP) has partially been unraveled, leading to adaptation of the dosage based on gender. However, besides age and gender, other factors might play a role in differences in sensitivity and side effects. The aim of this study is to design a pharmacokinetic/pharmacodynamic (PD) assay to identify appropriate treatment for different groups of patients, primarily dependent on differences in age and gender.

METHODS

This interventional pilot study was carried out in Ghent University Hospital, Belgium, between 2011 and 2013. Patients with NP were subjected to a water load test (15 mL/kg), as well as an administration of 120 µg dDAVP oral disintegrating tablet (ODT) followed by blood analysis to determine plasma dDAVP levels and urine analysis for diuresis rate, osmolality, free water clearance and sodium clearance.

RESULTS

Six female and six male patients were included (range 30-89 years old; mean age 69 years; SD 18). Three groups based on plasma dDAVP levels were found: (1) high (only women), (2) intermediate (only men) and (3) low plasma levels. For the nighttime samples (3-12 h after intake) men presented with significantly higher variation in PD response, whereas 12-15 h after dDAVP ODT intake women presented with a less predictable outcome, although all patients but one (female) have a prolonged PD effect.

CONCLUSION

This study suggests the need for individualized dose titration rather than fixed dose regimens in NP patients with bothersome symptoms. Gender, body weight and results of nocturnal free water and sodium clearance need to be taken into account for more accurate individualized treatment to result in high response rates and low side effects.