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.

Obstructive Sleep Apnea Syndrome as a Potential Cause of Nocturia in Younger Adults.

OBJECTIVES: To investigate the impact of age on the relationship between obstructive sleep apnea syndrome (OSAS), nocturia, and other lower urinary tract symptoms (LUTSs). METHODS: This was a secondary analysis study based on data derived from a previously conducted prospective observational cohort study on OSAS and nocturia. We analyzed 90 subjects who were suspected of having OSAS. Prior to polysomnography, we assessed International Prostate Symptom Score-Quality of Life scores, Overactive Bladder Symptom Scores, and International Consultation on Incontinence Modular Questionnaire-Nocturia Quality of Life scores to evaluate LUTSs. Nocturnal urine volume, night-time frequency, and night-time urine electrolyte content were measured during polysomnography. Patients were divided into groups according to age and OSAS severity determined using apnea-hypopnea index (AHI) scores. Young patients were those aged <65 years and elderly patients, ≥65 years. A multiple linear regression with multiple imputations was performed to examine the association of night-time frequency with demographic, polysomnographic, and clinical characteristics. RESULTS: In young patients, night-time frequency was significantly associated with nocturnal urine volume, AHI score, and total IPSS. However, night-time frequency in elderly subjects was not associated with demographic and polysomnographic characteristics. In order to compare the severity of OSAS, night-time frequency and urinary sodium content significantly increased only in young patients (P = .007 and .004, respectively). CONCLUSION: OSAS is a strong candidate of causative factor for nocturia in younger individuals. When a younger patient complains nocturia without any urological disorders, OSAS should be kept in mind as a potential cause of nocturia.

Diagnosing Nocturnal Polyuria from a Single Nocturnal Urine Sample.

BACKGROUND: Patients with nocturnal polyuria (NP) experience a unique surge in nocturnal diuresis rate during the early hours of sleep. OBJECTIVE: To determine the diagnostic utility of the volume and osmolality of a single early nocturnal urine sample in detecting NP. DESIGN, SETTING, AND PARTICIPANTS: Analysis of 1 am urine samples obtained from two prospective observational studies at Ghent University Hospital involving participants recruited from a urology ambulatory care unit and those who consulted a continence clinic. Nocturic participants (one or more nocturnal void[s]; n=176) were stratified based on the presence (n=87) or absence (n=89) of NP (>90ml/h). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Receiver operating characteristic curves with Youden's Index were used to determine cutoff values for urine volume and urine osmolality (Uosm). RESULTS AND LIMITATIONS: Individuals with NP demonstrated higher 1 am volume (400 [interquartile range 300-515] vs 210 [160-300] ml, area under the curve [AUC]=0.843, p< 0.001, cutoff = 350 ml) and lower Uosm (274 [201-348] vs 430 [320-664] mOsm/kg H2O, AUC=0.774, p<0.001, cutoff=314 mOsm/kg H2O) than those without NP. In combining cutoffs, the criteria of either 1 am volume ≥350ml or Uosm ≤314 mOsm/kg H2O were 85% sensitive and 75% specific for NP, while criteria of both 1 am volume ≥350ml and Uosm ≤314 mOsm/kg H2O were 60% sensitive and 92% specific for NP. Comparable AUC values, sensitivities, and specificities were observed in both men and women. Limitations include post hoc design and a relatively small study sample. CONCLUSIONS: Individuals with NP are more likely than those without NP to produce a higher volume of more dilute urine (ie, "aquaresis") in the early hours of sleep. Analysis of easily measurable parameters of the first nocturnal void (for which 1 am values serve as a surrogate) in men and women with nocturia can predict a diagnosis of NP with a reasonably high degree of sensitivity and specificity. PATIENT SUMMARY: Urologists often try to understand the specific reason why people wake up to urinate at night by asking them to record the amount of urine they make every time they go to the bathroom (also known as a "voiding diary") during the nighttime as well as the daytime-typically for a total of 1-3 days. In this study, we showed that an analysis of the composition of the urine that people produce when they first wake up to urinate at night might be sufficient to determine whether their symptoms are caused by excessive urine production or something else, and some people might find this urine study easier than keeping a voiding diary.

Urinary metabolites identified using metabolomic analysis as potential biomarkers of nocturia in elderly men.

PURPOSE: To investigate the association between nocturia and urinary metabolites in elderly men using metabolomic analysis. METHODS: We recruited 66 men aged 65-80 years. The 3-day frequency volume chart (FCV), International Prostate Symptom Score (IPSS), and quality of life score were used to assess micturition behavior. Participants with the total IPSS > 0 and ≥ 1.5 micturition on an average for three nights were included in the nocturia group. Participants with the total IPSS < 8 and < 1.5 micturition at night were included in the control group. We conducted a comprehensive metabolomic analysis of urine samples. Metabolites were compared between the groups using an unpaired t test. A multivariable logistic regression analysis was used to determine the relationship between nocturia and these metabolites. RESULTS: The nocturia and control groups consisted of 45 and 21 men, respectively. There were no differences in the background factors between the groups except for receiving anticholinergic drug and having life style-related diseases. The FVC revealed that nocturnal urine volume, 24 h micturition frequency, and nocturnal micturition frequency were significantly higher in the nocturia group than in the control group. The metabolomic analysis revealed 16 metabolites, which were differentially expressed between the groups. The multivariate analysis showed that increased serotonin level and decreased 3-hydroxypropionic acid and 3-indoleacetonitrile levels were associated with nocturia. CONCLUSIONS: These findings suggest that abnormal urinary metabolites including serotonin, 3-hydroxypropionic acid, and 3-indoleacetonitrile are involved in the pathogenesis of nocturia in elderly men.

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

OBJECTIVE: To clarify the relationships between daily salt intake and lower urinary tract symptoms. METHODS: A cross-sectional clinical study was carried out with 728 patients. Spot urine samples were collected to evaluate estimated daily salt intake. The patients were divided into two groups based on mean salt intake (9.2 g/day). Their urinary condition was evaluated using the Core Lower Urinary Tract Symptoms score and 3-day frequency volume charts. The influence of salt intake on lower urinary tract symptoms was investigated using multivariate logistic regression analysis. RESULTS: Daytime frequency (Q1) and nocturia (Q2) in the high salt intake group (H-salt group) were higher compared with those in the low salt intake group (L-salt group); P < 0.001). The quality of life scores and nocturnal polyuria index in the H-salt group were worse than those in the L-salt group (P < 0.001). Multivariate analyses showed daily salt intake is an independent worsening factor for high daytime frequency (odds ratio 2.32, 95% confidential interval 1.66-3.25, P < 0.001) and nocturia (odds ratio 3.05, 95% confidential interval 2.08-4.52, P < 0.001). Similarly, hypertension was identified as the independent variable for these symptoms. A limitation of the present study was that we recruited only patients with mild or no comorbidity. CONCLUSIONS: Excessive daily salt intake negatively affects pollakiuria and nocturia. The presence of hypertension can also represent a worsening factor for these symptoms. Although not shown by prospective study, the appropriate control of salt intake and blood pressure might be important for the treatment of pollakiuria and nocturia.

Basic or extended urine sampling to analyse urine production?

BACKGROUND: Frequency volume charts are valuable tools to objectify urine production in patients with nocturia, enuresis or nocturnal incontinence. Analyses of daytime and nighttime urine (=basic collection) or analyses of urine samples collected every 3 h (=extended collection) extend this evaluation by describing circadian patterns of water and solute diuresis (=renal function profiles). AIM: To assess intra-individual correlation and agreement between renal function profiles provided using basic and extended urine collections, and using two extended urine collections. To create a short-form of the extended collection. METHODS: This prospective observational study was executed at Ghent University Hospital, Belgium. Study participation was open for anyone visiting the hospital. Participants collected one basic and two extended 24-h urine collections. Urinary levels of osmolality, sodium and creatinine were determined. RESULTS: There was a moderate to strong correlation between results of basic and extended urinalyses. Comparing both extended urinalyses showed a moderate correlation between the eight individual samples and a weak to strong correlation between the mean daytime and nighttime values of renal functions. Different samples could be considered as most representative for mean daytime values, while all samples collected between 03 and 05am showed the highest agreement with mean nighttime values of renal function. CONCLUSION: Since there is a good correlation and agreement between basic and extended urine collections to study the mechanisms underlying urine production, the choice of urine sampling method to evaluate urine production depends on the purpose. A nighttime-only urine sample collected between 03 and 05am may be the most practical approach.

Exploring nocturia: gender, age, and causes.

PURPOSE: This study aims to clarify differences in parameters based on frequency volume chart (FVC) and on daytime and nighttime urine according to the nocturia frequency, age, and gender. MATERIALS AND METHODS: This observational study was executed between 2011 and 2013. Participants (>18 years, ≤65 years) with or without nocturia (controls) were included and completed a 72 hr FVC; osmolality and sodium excretion were analyzed on daytime and nighttime urine. RESULTS: (1) Nocturia severity: Compared to controls (N = 38), those with ≥2 nocturia episodes (N = 29) have higher nocturnal voided volume (NVV) (P < 0.001) based on increased sodium excretion (P = 0.003) and lower functional bladder capacity (P < 0.001). Those with one nocturia episode (N = 21) present with lower bladder capacity (P = 0.005). (2) Gender: women with 1 and ≥2 episodes have lower bladder capacity than controls (P = 0.047 and P < 0.001, respectively). Men with ≥2 episodes present with increased NVV (P = 0.001) and decreased bladder capacity (P = 0.049). (3) Age: Younger participants (<44 years) with ≥2 nocturia episodes present with lower functional bladder capacity than controls (P < 0.001). Older participants (45-65 years) present with both increasing NVV and decreasing bladder capacity with increasing nocturia frequency (P < 0.001); sodium excretion is higher in those with ≥2 episodes (P = 0.029). (4) Causes: the percentage of isolated NP decreases (P = 0.005), whereas the combination of both causes increases with increase in number of nocturia episodes (P = 0.020). CONCLUSIONS: The mismatch between functional bladder capacity and NVV with increasing nocturia frequency demands a comprehensive diagnostic approach to subtype the patient, which involves anamnesis, FVC, and analysis of daytime and nighttime urine.

The impact of obstructive sleep apnea syndrome on nocturnal urine production in older men with nocturia.

OBJECTIVE: To investigate the impact of obstructive sleep apnea syndrome (OSAS) on night-time secretion of brain natriuretic peptide (BNP) and antidiuretic hormone (ADH) in older men with nocturia accompanied by nocturnal polyuria. MATERIALS AND METHODS: One hundred six men with nocturia aged ≥ 60 years underwent full-night polysomnography to determine whether they had OSAS. Blood count, standard chemistry panel, BNP, urinary ADH, urinary creatinine (u-Cre), and urinary osmolarity were measured at 6:00 AM, and a frequency volume chart was recorded on the same day that polysomnography was performed. RESULTS: We evaluated 83 patients after excluding 18 with mild OSAS and 5 with nocturnal polyuria index <0.35. Participants with OSAS had higher apnea-hypopnea index (P < .0001) than those without OSAS. Body mass index and systolic blood pressure were higher in OSAS patients than those in the control group. BNP was higher in the OSAS patients than in the control patients (48.6 ± 41.4 vs 30.7 ± 31.5; P = .0006). On urinalysis, OSAS patients showed higher urinary sodium and u-Cre secretion than controls (24.7 ± 11.3 vs 16.2 ± 5.1; P <.0001). Urine osmolarity was also higher in OSAS patients than in the control patients (616 ± 172 vs 516 ± 174; P = .0285). There was no significant difference in urinary ADH and u-Cre (6.7 ± 10.4 vs 6.8 ± 7.8; P = .3617) between the 2 groups. CONCLUSION: Our results indicated that older men with nocturnal polyuria and OSAS did not compensate their fluid imbalance presented with decreased secretion of ADH but increased BNP level.

Evaluation of nocturnal bladder capacity and nocturnal urine volume in nocturnal enuresis.

OBJECTIVE: To investigate the diagnostic accuracies of maximum voided volume (MVV) and first morning urine osmolality and compare these with accuracies of nocturnal bladder capacity (NBC) and nocturnal urine volume, respectively, in children with nocturnal enuresis. MATERIALS AND METHODS: A total of 70 children with nocturnal enuresis were assessed (mean age 7.1 ± 2.2 years). Baseline parameters were obtained by measuring MVV using a voiding diary, first morning urine osmolality on a wetting day, diaper weight by checking twice per night and first morning urine volume. RESULTS: The proportions of small NBC and small MVV were 34.3% (24 cases) and 55.7% (39 cases), respectively. The proportions of low osmolality of first morning urine and nocturnal polyuria (NP) were 45.7% (32 cases) and 25.7% (18 cases), respectively. The sensitivity and specificity of small MVV for small NBC were 53.8% and 90.3%, respectively; the sensitivity and specificity of first morning urine osmolality for NP were 33.3% and 50.0%, respectively. CONCLUSIONS: The diagnostic accuracies of MVV and urine osmolality for small NBC and NP were only modest to low.

Association between melatonin secretion and nocturia in elderly individuals: a cross-sectional study of the HEIJO-KYO cohort.

PURPOSE: Nocturnal voids are regulated by circadian biological rhythms, including decreased urine production and increased bladder storage capacity at night. A previous experimental study suggested that exogenous melatonin decreases urine production and increases bladder capacity in rats. However, little is known about whether melatonin secretion, which is considerably lower than exogenous melatonin, is associated with nocturia in humans. We evaluated the association between melatonin secretion and nocturia. MATERIALS AND METHODS: In this cross-sectional study we examined 861 community based elderly individuals with a mean age of 72.1 years. We measured nocturnal void frequency and overnight urinary 6-sulfatoxymelatonin excretion as an index of melatonin secretion. Nocturia was defined as 2 or more nocturnal voids. RESULTS: Univariate comparisons between the 261 and 600 study participants with and without nocturia, respectively, showed marginal to significant associations of nocturia with age, gender, body mass index, estimated glomerular filtration rate, calcium channel blockers, benign prostatic hyperplasia, total voided urine volume, urinary 6-sulfatoxymelatonin, duration in bed, day length, and daytime and nighttime physical activity. The multivariate logistic regression model adjusted for the former confounding factors revealed that higher urinary 6-sulfatoxymelatonin was significantly associated with a lower nocturia OR (adjusted OR 0.73, 95% CI 0.56-0.96, p=0.023). After adjustment for age, gender and duration in bed the mean volume of a single voided urine significantly increased with tertiles of increasing urinary 6-sulfatoxymelatonin (p for trend=0.022). CONCLUSIONS: Melatonin secretion is significantly and inversely associated with nocturia in a general elderly population.

Prevalence, incidence, and resolution of nocturnal polyuria in a longitudinal community-based study in older men: the Krimpen study.

BACKGROUND: Nocturnal polyuria (NP) is common in older men and can lead to nocturia. However, no longitudinal data are available on the natural history of NP. OBJECTIVE: To determine prevalence, incidence, and resolution rates of NP. DESIGN, SETTING, AND PARTICIPANTS: A longitudinal, community-based study was conducted among 1688 men aged 50-78 yr in Krimpen aan den IJssel, The Netherlands (reference date: 1995), with planned follow-up rounds at 2, 4, and 6 yr. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: NP was determined with frequency-volume charts. Two definitions of NP were used: (1) a nocturnal urine production (NUP) of >90 ml/h (NUP90) and (2) the nocturnal voided volume plus first morning void being >33% of the 24-h voided volume (NUV33). Nocturia was defined as two or more voids per night. We determined the prevalence of NP at each study round. At first follow-up, we determined the incidence in men without baseline NP and the resolution in men with baseline NP. Prevalence of NP in men with or without nocturia was also determined. RESULTS AND LIMITATIONS: At baseline, the prevalence of NUP90 was 15.0% and increased to 21.7% after 6.5 yr, whereas the prevalence of NUV33 was 77.8% at baseline and 80.5% after 6.5 yr. At 2.1 yr of follow-up, the incidences of NUP90 and NUV33 were 13.6% and 60.3%, respectively, and the resolution rates were 57.0% and 17.8%, respectively. Because of this fluctuation in NP, no reliable long-term incidences could be calculated. At baseline, NUP90 was prevalent in 27.7% of men with nocturia and in 8.0% of those without nocturia. At baseline, NUV33 was prevalent in 91.9% of men with nocturia and in 70.1% of men without nocturia. CONCLUSIONS: Due to the fluctuation of NP, it is advisable to first determine its chronicity and cause before starting treatment. Because of the high prevalence of NP in men without nocturia, NUV33 should be reconsidered as a discriminative definition of NP.

[Urodynamic changes in patients with obstructive sleep apnea-hypopnea syndrome and nocturnal polyuria].

OBJECTIVE: To investigate the urodynamic changes in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) and nocturnal polyuria. METHODS: From Sept. 2002 to Jun. 2008, 23 patients with nocturnal polyuria were diagnosed as having OSAHS by polysomnography (PSG). The number and output of nocturia, the osmotic pressure and the excretion of Na(+) were recorded during both the PSG night and CPAP titrating night. Plasma levels of brain natriuretic peptide (BNP) and atrial natriuretic peptides (ANP) were also measured at 11PM in the 2 nights and 7AM in the next mornings. Urodynamic studies including urine flow, bladder pressure during filling, pressure-flow study during voiding and urethral pressure were carried out in these patients. Urodynamic studies were performed again after treatment with CPAP for 3 months. RESULTS: PSG showed that the patients with nocturnal polyuria had moderate to severe OSAHS, in which the apnea-hypopnea index (AHI) being 48 ± 15 events per hour. The number of nocturnal voiding during the PSG night was more than that during the CPAP titrating night. During the PSG night, the output of nocturia, the nocturia excretion of Na(+), ANP levels (at 7am in the next morning after PSG night) increased and the osmotic pressure of nocturia decreased. CPAP therapy could reverse these abnormalities. The main characteristics of urodynamics in these patients included weak detrusor contraction, hypoesthesia in filling cystometry, and decreased bladder compliance, and detrusor external sphincter dyssynergia. After 3 months of CPAP treatment, both the motility of the detrusor of bladder and the bladder compliance improved. CONCLUSIONS: CPAP therapy can effectively reverse the nocturnal polyuria in OSAHS patients. In OSAHS patients, the features of nocturia, including the changes of output, osmotic pressure and the excretion of Na(+), may be related to the secretion of high-level of ANP. During the course of chronic progressively OSAHS pathophysiology, detrusor function of bladder may be damaged. CPAP therapy could decrease the nocturnal excretion of ANP, and improve the motility of the detrusor of bladder.

Gender difference in antidiuretic response to desmopressin.

Increased age and female gender are well-known risk factors for the development of desmopressin-induced hyponatremia. However, little focus has been on exploring gender differences in the antidiuretic response to desmopressin. Based on an exploratory analysis from three clinical trials, we report a significant gender difference in the effects of desmopressin on nocturnal urine volume that could not be explained by pharmacokinetic differences. Mean desmopressin concentration profiles were tested for covariates, and age and gender were not statistically significant and only weight was significant for log(C(max)) (P = 0.0183) and borderline significant for log(AUC) (P = 0.0571). The decrease in nocturnal urine volume in nocturia patients treated with desmopressin over 28 days was significantly larger for women at the lower desmopressin melt doses of 10 and 25 µg than for men. The ED(50) for men was modeled to be 43.2 µg and 16.1 µg for women, with the ED(50) men/women estimated to be 2.7 (1.3-8.1 95% CI), corresponding to significantly higher sensitivity to desmopressin in women. An increasing incidence of hyponatremia with increasing dose was found, and at the highest dose level of 100 µg decreases in serum sodium were approximately twofold greater in women over 50 yr of age than in men. A new dose recommendation stratified by gender is suggested in the treatment of nocturia: for men, 50- to 100-µg melt is an efficacious and safe dose, while for women a dose of 25 µg melt is recommended as efficacious with no observed incidences of hyponatremia. Areas for further research are proposed to uncover pathophysiological mechanism(s) behind these gender differences.

Relationship between nocturnal urine volume, leg edema, and urinary antidiuretic hormone in older men.

OBJECTIVE: To evaluate the relationship between leg edema, nocturnal urine volume (NUV), and the secretion of antidiuretic hormone (ADH) during the night, and to investigate the principal factors affecting nocturnal polyuria in older men. METHOD: A total of 74 male inpatients more than 50 years of age were enrolled in this study. Blood count, standard chemistry panel, brain natriuretic peptide (BNP), urinary ADH (u-ADH), urinary creatinine (u-Cre), and urinary osmolarity were measured at 6:00 am. Keeping a frequency volume chart, bioelectric impedance analysis was performed at 5 pm. Leg edema was measured as an edema ratio, using the following formula: extracellular water [L)/(extracellular water [L) + intracellular water [L)) in legs. RESULTS: A total of 66 patients were evaluated. NUV had a significant positive correlation with leg edema (r = 0.32, P = .008), negative correlation with u-ADH/u-Cre (r = -0.37, P = .003) but not BNP. Leg edema had a significant positive correlation with the level of BNP (r = 0.33, P = .012) and negative correlation with u-ADH/u-Cre (r = -0.4, P = .001). However a partial correlation showed that there was no significant correlation between NUV and leg edema. A multivariate logistic model showed that only u-ADH/u-Cre was an independent predictive variable of nocturnal polyuria. CONCLUSIONS: This study suggested that leg edema influenced nocturnal urine volume with an associated decrease in ADH secretion but not directly. ADH secretion during the night was the principal factor affecting NP in older men.

[Treatment of chronic cystitis in postmenopausal women].

A randomized double blind controlled trial of intravaginal cream ovestin (estriol) was conducted in 102 postmenopausal females with chronic cystitis. The patients were divided into two groups. Group 1 (n = 52) received standard therapy, group 2 (n = 50) received standard therapy plus ovestin (daily intravaginal administration for 2 weeks, then twice a week). Final results were evaluated 1 year after therapy. Before the treatment 94% patients had subnormal levels of blood estradiol. One year after the treatment positive results were achieved in 91.3% patients of group 2 and 65.8% of group 1 (p < 0.001). In group 2 patients ovestin significantly reduced pollakiuria, nocturia, episodes of urgent urinary incontinence, painful voiding. Percentage of patients with leukocyturia diminished from 100 to 8%, bacteriuria--from 74 to 4%, with vaginal lactobacilli increased from 0 to 56%, enterobacterial contamination of the vagina fell from 66 to 12%. Vaginal pH decreased from 6.0 to 3.6. Addition of ovestin to standard therapy reduced the number of cystitis recurrences 11-fold, days of antibacterial therapy--12.4-fold. Side effects of ovestin (vaginal pruritus) were seen in 4% patients.

Short-term effects of desmopressin on water and electrolyte excretion in adults with nocturnal polyuria.

PURPOSE: Increased calcium excretion due to desmopressin has been reported in children with nocturnal enuresis. Desmopressin is often used to treat adult patients with nocturnal polyuria. However, data on the effect of desmopressin on water/electrolyte excretion in adults are scarce. We present the short-term effects of desmopressin on water and electrolyte excretion in adult patients with nocturnal polyuria. MATERIALS AND METHODS: A total of 16 male patients with nocturnal polyuria, mean age 76.3 years, received 0.1 or 0.2 mg desmopressin before sleep. Frequency volume chart was recorded, and daytime and nighttime urine samples were collected separately before and after desmopressin administration. Urinary excretions of sodium, potassium and calcium were determined, and compared before and after treatment with desmopressin. RESULTS: Desmopressin significantly increased urine osmolality, decreased nocturnal total urine volume, reduced the ratio of nocturnal urine volume-to-whole day urine volume and decreased nocturnal voiding frequency. Nocturnal urinary excretion of calcium (mean 0.137 vs 0.169 mg/kg body weight per hour, p = 0.004) and whole day excretion of calcium (mean 165.9 vs 200.0 mg per day, p = 0.012) were increased after desmopressin treatment. Nocturnal urinary potassium excretion (mean 0.030 vs 0.025 mEq/kg body weight per hour, p = 0.030) and whole day potassium excretion (mean 40.7 vs 36.1 mEq per day, p = 0.017) were decreased by desmopressin treatment. However, desmopressin treatment did not significantly change urinary secretion of sodium and chloride at nighttime or for the whole day. CONCLUSIONS: Desmopressin reduces nocturnal urine volume and nocturnal voiding frequency in male patients with nocturnal polyuria. However, increased calcium and decreased potassium excretion following desmopressin treatment deserve attention particularly when it is used on a long-term basis.