HYPERNATRIURIA AND KALIURESIS IN ENURETIC CHILDREN AND THE DIURNAL VARIATION

Combination treatment of nocturnal enuresis with desmopressin and indomethacin

BACKGROUND

We investigated the effect of combining indomethacin and desmopressin in treating children with monosymptomatic nocturnal enuresis (MNE) and desmopressin-resistant nocturnal polyuria.

METHODS

Twenty-three children with MNE, nocturnal polyuria, and partial or no response to desmopressin were recruited from incontinence clinics of our tertiary referral center. We used a randomized single-arm crossover placebo-controlled study design consisting of two 3-week treatment periods with a combination of desmopressin (0.4 mg) and indomethacin (50 mg) or desmopressin and placebo at bedtime. Home recordings at baseline and for the final 2 weeks of each treatment period were performed and included nocturnal urine output measurements. The number of dry nights achieved and reduction in the nocturnal urine output were the main effect parameters. Student's t test and Pearson's correlation coefficient were used for statistical analysis.

RESULTS

The addition of indomethacin to desmopressin significantly reduced nocturnal urine output (from 324 ± 14 ml to 258 ± 13 ml, p < 0.001). This did not lead to more dry nights in all children, and we found no statistically significant reduction in enuresis frequency (from 68 % ± 0.1 to 56 % ± 0.1, p = 0.24).

CONCLUSIONS

Addition of indomethacin to desmopressin can further reduce nocturnal urine output in children with MNE and desmopressin-resistant nocturnal polyuria. The combination treatment does not, however, improve outcome in terms of frequency of nights with enuresis. The dissociation of antidiuretic and antienuretic effect may reflect nocturnal bladder reservoir dysfunction in children who present with normal daytime bladder function.

Effect of indomethacin on desmopressin resistant nocturnal polyuria and nocturnal enuresis

PURPOSE

We evaluated the acute effect of indomethacin on renal water and solute handling in children with coexisting monosymptomatic nocturnal enuresis and desmopressin resistant nocturnal polyuria, and in healthy controls.

MATERIALS AND METHODS

A total of 23 subjects were recruited, consisting of 12 children with monosymptomatic nocturnal enuresis and nocturnal polyuria with partial or no response to desmopressin, and 11 age matched controls. Children completed a 48-hour inpatient study protocol consisting of fractional urine collections and blood samples. Sodium and water intake were standardized. During the second night a dose of 50 mg indomethacin was administered orally before bedtime. Diuresis, urine osmolalities, clearances and fractional excretions were calculated for sodium, potassium, urea, osmoles and solute-free water. Renin, angiotensin II, aldosterone and atrial natriuretic peptide were measured in plasma. Prostaglandin E(2) was measured in urine.

RESULTS

Indomethacin markedly decreased the nocturnal sodium, urea and osmotic excretion in children with enuresis and controls. The overall effect on nocturnal urine output was inconsistent in the group with enuresis. Subjects in whom nocturnal diuresis was decreased following administration of indomethacin remained dry.

CONCLUSIONS

Prostaglandin inhibition leads to antidiuresis, reducing the amount of sodium, urea and osmotic excretion in children with monosymptomatic nocturnal enuresis and desmopressin resistant nocturnal polyuria. The sodium regulating hormones do not seem to mediate these processes. The overall effect in desmopressin nonresponders with nocturnal polyuria is variable. The extent to which indomethacin can be applied in the treatment of enuresis needs further evaluation.

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.

Nitric Oxide Synthase Gene Polymorphisms in Children with Primary Nocturnal Enuresis: A Preliminary Study

AIMS

Recent studies demonstrated some differences in urinary electrolytes of enuretic children. Intrarenal nitric oxide (NO) serves as a major regulator of renal sodium and water excretion like an endogenous diuretic. This study aimed to investigate endothelial (eNOS), and neuronal (nNOS) NO synthase gene polymorphisms in children with primary nocturnal enuresis (PNE).

MATERIALS AND METHODS

The eNOS gene polymorphism was investigated in 171 Turkish children (57 PNE cases and 114 healthy, non-enuretic controls), and nNOS gene polymorphism was determined in 158 Turkish children (83 PNE cases and 75 healthy, non-enuretic controls). The glu298asp (G/T) polymorphism of the eNOS and C276T (C/T) polymorphism of nNOS genes were genotyped using PCR.

RESULTS

The distribution of GG, TG, and TT genotypes for eNOS gene was 48%, 33%, and 19% in PNE, compared with 61%, 26%, and 13% in the controls (p > 0.05). The distribution of CC, TC, TT and genotypes for nNOS gene was 31%, 29%, and 40% in PNE compared with 10%, 43%, and 47% in the controls. CC genotype was found higher in enuretic children (p = 0.002). The eNOS and nNOS gene polymorphisms were not associated with positive family history, frequency of enuresis, and clinical response to desmopressin.

CONCLUSIONS

This study is the first to search the NOS gene polymorphisms in children with PNE. It was determined that eNOS gene polymorphism may not be associated with PNE, while nNOS gene polymorphism, a predominantly CC genotype, may be associated with PNE in Turkish children. Further studies with larger samples together with the detection of enuresis gene may help determine the exact role of nNOS gene polymorphism in enuresis.

Partial Response to Intranasal Desmopressin in Children With Monosymptomatic Nocturnal Enuresis is Related to Persistent Nocturnal Polyuria on Wet Nights

PURPOSE

The anti-incontinence effect of desmopressin resides in its concentrating capacity and antidiuretic properties. We compared nighttime urine production on wet and dry nights in a highly selected study population of children with monosymptomatic nocturnal enuresis associated with proved nocturnal polyuria who responded only partially to intranasal desmopressin.

MATERIALS AND METHODS

We retrospectively analyzed 39 home recordings of nocturnal urine production and maximum voided volume in children 7 to 19 years old (median 8.9) with monosymptomatic nocturnal enuresis with nocturnal polyuria who had a partial response to desmopressin. Nocturnal diuresis volume and maximum voided volume were documented at baseline (14 days) and during 3 months of followup.

RESULTS

Baseline nocturnal urine output (439 +/- 39 ml) was significantly higher than the maximum voided volume (346 +/- 93 ml, p <0.01). During desmopressin treatment nocturnal urine output on wet nights (405 +/- 113 ml) differed significantly from that on dry nights (241 +/- 45 ml). During treatment nocturnal urine output on wet nights did not differ from baseline values.

CONCLUSIONS

Persistence of nocturnal polyuria on wet nights in partial desmopressin responders may be related to an insufficient antidiuretic effect. In addition to poor compliance and suboptimal dosing, the poor bioavailability of intranasal desmopressin may be a pathogenic factor. Further prospective studies are needed.

Characteristics of a Tertiary Center Enuresis Population, With Special Emphasis on the Relation Among Nocturnal Diuresis, Functional Bladder Capacity and Desmopressin Response

PURPOSE

We evaluated pretreatment values of circadian rhythm of urine production and urine osmolality in children with different subtypes of monosymptomatic nocturnal enuresis, and investigated their predictive value for desmopressin response.

MATERIALS AND METHODS

We assessed 125 consecutive patients with monosymptomatic nocturnal enuresis, nocturnal polyuria and normal functional bladder capacity who were treated with desmopressin for a median of 17 months (range 3 to 100). Patients were characterized according to the desmopressin response as full responders or nonfull responders. Baseline parameters were obtained from a 2-week home recording diary. Results were compared with 125 consecutive children with monosymptomatic nocturnal enuresis and reduced functional bladder capacity.

RESULTS

No differences in pretreatment values of functional bladder capacity, circadian rhythm of urine production or urine osmolality were found between desmopressin full responders and nonfull responders. Patients with nocturnal polyuria had a significantly higher 24-hour diuresis volume compared to children with reduced functional bladder capacity. Some children with reduced functional bladder capacity also had nocturnal polyuria.

CONCLUSIONS

Our findings show that the characteristics of nocturnal polyuria in patients with monosymptomatic nocturnal enuresis and normal functional bladder capacity do not predict desmopressin response. The wide overlap among the different subgroups suggests that dividing patients with monosymptomatic nocturnal enuresis into those with reduced functional bladder capacity and those with desmopressin responsive nocturnal polyuria might be insufficient. Patients with nocturnal polyuria and normal functional bladder capacity have a significantly higher daytime and nighttime diuresis volume compared to children with reduced functional bladder capacity, suggesting a direct correlation between daytime fluid intake and nocturnal diuresis rate. Some children with reduced functional bladder capacity also have nocturnal polyuria.

Urinary calcium excretion in healthy children and children with primary monosymptomatic nocturnal enuresis

PURPOSE

We investigated the role of urinary Ca excretion in monosymptomatic nocturnal enuresis, and defined normality and intra-individual variability in Ca excretion in healthy children.

MATERIALS AND METHODS

We included 46 Danish children with desmopressin resistant nocturnal enuresis and 96 healthy controls. We performed fractional urine collections at home during 2 days in controls or during hospitalization in children with enuresis. Urine volume, osmolality, and Ca and creatinine measurements were performed and Ca-to-creatinine ratios were calculated and compared between groups. Based on nocturnal urine output children with enuresis were characterized as having polyuria (nocturnal urine volume greater than 130% of expected bladder capacity) or not having polyuria.

RESULTS

We did not find any differences in controls compared with children with enuresis who did not and did have nocturnal polyuria in daytime Ca excretion (mean +/- SE 0.121 +/- 0.012, 0.078 +/- 0.014 and 0.095 +/- 0.020 mg/mg creatinine), nighttime Ca excretion (0.115 +/- 0.011, 0.092 +/- 0.019 and 0.139 +/- 0.029 mg/mg creatinine) or 24-hour Ca excretion (0.118 +/- 0.011, 0.083 +/- 0.014 and 0.106 +/- 0.020 mg/mg creatinine, respectively). Urinary Ca excretion was not influenced by patient age, sex or body weight and, furthermore, we did not find evidence of diurnal variation. However, we observed considerable intra-individual variability in diurnal, nocturnal and total 24-hour urinary Ca-to-creatinine ratios.

CONCLUSIONS

These observations contradict several previous reports and speculations on a role of Ca in the pathogenesis of nocturnal enuresis.

Nocturnal polyuria in monosymptomatic nocturnal enuresis refractory to desmopressin treatment

The transition from day to night is associated with a pronounced decline in diuresis with reductions in the amount of excreted water, electrolytes, and other end products of our metabolism. Failure to do so leads to a large urine output at night, a condition known as nocturnal polyuria, encountered in a large proportion of children with nocturnal enuresis. The aim of this study was to clarify the mechanisms responsible for the nocturnal polyuria seen in enuretics with inadequate response to desmopressin (dDAVP). Forty-six enuretics (7-14 yr of age) and fifteen age-matched controls were admitted for a 24-h protocol with standardized fluid and sodium intake, comprising urine collections, blood sampling, and blood pressure monitoring. We included patients with severe enuresis (5 +/- 1 wet nights/wk) showing <50% reduction in wet nights on dDAVP. We characterized the patients on the basis of their nocturnal urine production. The children with nocturnal polyuria excreted larger amounts of sodium and urea at night than nonpolyurics and controls. Solute-free water reabsorption as well as urinary arginine vasopressin and aquaporin-2 excretion were normal in polyurics, and no differences were found in atrial natriuretic peptide, angiotensin II, aldosterone, and renin levels. Urinary prostaglandin E2 (PGE2) excretion was significantly higher in polyurics. The nocturnal polyuria in children with dDAVP-resistant nocturnal enuresis seems to be the result of augmented sodium and urea excretion. The high urinary PGE2 levels found in these children point toward a role for increased prostaglandin synthesis in the pathogenesis of enuresis-related polyuria.

SODIUM FRACTION EXCRETION RATE IN NOCTURNAL ENURESIS CORRELATES WITH NOCTURNAL POLYURIA AND OSMOLALITY

PURPOSE

We verify the sodium fraction excretion rate (FE Na) and potassium fraction excretion (FE K) rates in monosymptomatic nocturnal enuresis. We also correlate FE Na and FE K to urinary osmolality, nocturnal polyuria and vasopressin in the same population.

MATERIALS AND METHODS

A total of 438 children 6 to 15 years old (mean age 9.7) presenting with monosymptomatic nocturnal enuresis were recruited from different centers. Inclusion criteria were 3 or greater wet nights a week, no daytime incontinence and no treatment in the previous 2 months. Exclusion criteria were cardiopathy, endocrinopathy, psychiatric problems and urinary tract abnormalities. Micturition chart, diurnal (8 am to 8 pm) and nocturnal (8 pm to 8 am) urine collection, including separate diuresis volumes, (Na, K and Ca) electrolytes and osmolality were evaluated, as well as serum electrolytes, creatinine and nocturnal (4 am) vasopressin. Diurnal and nocturnal FE K and FE Na were calculated. ANOVA test, chi-square test, Student's t test and Pearson correlation test were used for statistical analysis.

RESULTS

: Nocturnal polyuria (diurnal to nocturnal diuresis ratio less than 1) was found in 273 children (62.3%, group 1 and nocturnal urine volumes were normal in 165 with enuresis (37.7%, group 2). Nocturnal FE Na was abnormal in 179 children (40.8%), including 118 in group 1 (43.2%) and 61 in group 2 (36.9%) (chi-square not significant). FE Na was also increased in nocturnal versus daytime diuresis (Student's t test p <0.001). In group 1 nocturnal FE Na correlated with nocturnal diuresis (Pearson correlation p = 0.003, r = +0.175), while daytime FE Na and nocturnal FE Na correlated with diurnal diuresis (Pearson correlation p = 0.001, r = +0.225 and Pearson correlation p = 0.001, r = +0.209, respectively). In group 2 nocturnal FE Na did not correlate with diuresis (Pearson correlation p = 0.103, r = +0.128) but correlated with vasopressin values (Pearson correlation p = 0.042, r = -0.205). Urine osmolality was reduced in 140 children (31.9%) and correlated with nocturnal diuresis (Pearson correlation p = 0.003, r = -0.321). Vasopressin was decreased in 332 children (75.8%, 62.6% in group 1 and 13.2% in group 2). No significant difference was found between sexes and age of enuretic subgroups.

CONCLUSIONS

Nocturnal FE Na correlates with nocturnal diuresis, whereas daytime FE Na does not. FE K in daytime and nighttime diuresis does not statistically differ in nocturnal polyuric and nonpolyuric enuretic groups. Osmolality correlates with nocturnal diuresis, and vasopressin at 4 am was lower in the nocturnal polyuric group. The hypothesis of a subset of enuretic patients presenting with nocturnal polyuria associated with high nocturnal natriuria and low vasopressin values has been confirmed.

Vasopressin and hypercalciuria in enuresis: a reappraisal

OBJECTIVE

To test the hypotheses that vasopressin deficiency or hypercalciuria are important in polyuric and non-polyuric bedwetting, as nocturnal polyuria is a pathogenetic factor in enuresis responsive to antidiuretic therapy with desmopressin.

SUBJECTS AND METHODS

Vasopressin deficiency has been implicated as a cause of nocturnal polyuria, but measurements of vasopressin in plasma have given contradictory results, because the hormone is released in pulses. Urinary levels reflect the secretion over longer periods. Hypercalciuria has also been proposed as a pathogenetic factor. Twenty-eight enuretic children who responded to desmopressin therapy with or without added anticholinergic agents (diuresis-dependent enuresis, DE), 15 children with therapy-resistant enuresis (not diuresis-dependent, NDE) and 51 continent controls were assessed. Urinary vasopressin, calcium and osmolality were measured in the morning after a 12-h thirst provocation. Urine production was recorded for 2 days.

RESULTS

Because most data were not normally distributed, the values are expressed as the median (range). There were no differences in urine osmolality; i.e. con-trols 919 (636-1232), DE 849 (462-1149), NDE 968 (664-1191) mOsml/kg); vasopressin, controls 34 (8-983), DE 26 (9-295), NDE 50 (9-116) pmol/L; or calcium excretion (expressed as the calcium/creatinine ratio), controls 0.16 (0.01-0.71), DE 0.14 (0.04-0.67), and NDE 0.23 (0.03-0.69). The DE group produced more urine, at 18.4 (9.2-52.5) mL/kg/day, than the other groups, i.e. control 12.7 (8.3-42.8) and NDE 12.1 (6.3-36.8) mL/kg/day (P = 0.008).

CONCLUSION

All enuretic children with nocturnal polyuria do not have vasopressin deficiency. The urinary calcium excretion does not differ between enuretic and dry children.

Enuresis: A maturational lag

ENURESIS IS NOT A DISEASE, BUT A DISORDER CAUSED BY DELAYS IN THE MATURATION OF THREE PHYSIOLOGICAL PROCESSES: persistence of spontaneous bladder contractions, bladder volume exceeding the nocturnal functional bladder capacity and persistence of elevated sleep/arousal thresholds. Enuresis has been subtyped into two different groups, depending on whether the predominant feature is frequent small voidings (excessive bladder contractions) or large urinary volume (volume-dependent). The clinical pattern demonstrated by the enuretic child depends on the severity of the maturational lag. In practice, a mix of these types is most common.