Osmoregulation and desmopressin pharmacokinetics in enuretic children

First-morning urine osmolality and nocturnal enuresis in children: A single-center prospective cohort study

PURPOSE

To investigate the treatment outcome of nocturnal enuresis (NE) according to first-morning urine osmolality (Uosm) before treatment.

MATERIALS AND METHODS

Ninety-nine children (mean age, 7.2±2.1 y) with NE were enrolled in this retrospective study and divided into two groups according to first-morning Uosm results, that is, into a low Uosm group (<800 mOsm/L; 38 cases, 38.4%) or a high Uosm group (≥800 mOsm/L; 61 cases, 61.6%). Baseline parameters were obtained from frequency volume charts of at least 2 days, uroflowmetry, post-void residual volume, and a questionnaire for the presence of frequency, urgency, and urinary incontinence. Standard urotherapy and pharmacological treatment were administered initially in all cases. Enuresis frequency and response rates were analyzed at around 1 month and 3 months after treatment initiation.

RESULTS

The level of first-morning Uosm was 997.1±119.6 mOsm/L in high Uosm group and 600.9±155.9 mOsm/L in low Uosm group (p<0.001), and first-morning voided volume (p=0.021) and total voided volume (p=0.019) were significantly greater in the low Uosm group. Furthermore, a significantly higher percentage of children in the low Uosm group had a response rate of ≥50% (CR or PR) at 1 month (50.0% vs. 24.6%; p=0.010) and 3 months (63.2% vs. 36.1%; p=0.009).

CONCLUSIONS

Treatment response rates are higher for children with NE with a lower first-morning Uosm.

Pretreatment morning urine osmolality and oral desmopressin lyophilisate treatment outcome in patients with primary monosymptomatic enuresis

PURPOSE

To determine the association between urine osmolality (Uosm) in patients with primary monosymptomatic enuresis (PMNE) and response to desmopressin (dDAVP) lyophilisate.

METHODS

This was a prospective cohort study that included 419 children with enuresis seen in outpatient clinic between October 2017 and October 2019. Patient workup included symptom checklist, 48 h frequency/volume chart, kidney and bladder ultrasound, uroflow, urinalysis and culture, spot urine Ca/creatinine, and first-morning Uosm. Patients < 5 years, with secondary enuresis, or loss of follow-up were excluded. Oral dDAVP lyophilisate was recommended to all with PMNE and normal bladder capacity. After 1 month of therapy, initial success was assessed according to ICCS. Significant predictor variables for complete response were identified and analyzed using correlation coefficients and binary logistic regression.

RESULTS

There were 48 patients with PMNE who received dDAVP and were followed for treatment success. Partial and complete responses were achieved for 14 (29.2%) and 20 cases (41.7%), respectively. Older age and lower Uosm were found to be significantly in favor of complete response to dDAVP lyophilisate, P = 0.007 and 0.033, respectively. ROC analysis determined the Uosm of ≤ 814 mOsm/kg as a cut-off value for complete success (sensitivity 65% and specificity 75%, AUC = 68.2%). The odds ratio for complete success for selected cut-off value was 5.57 (95% CI 1.588-19.551, P = 0.007).

CONCLUSION

High pretreatment morning Uosm (> 814 mOsm/kg) might be suggestive of an alternative treatment to dDAVP lyophilisate in PMNE because of the higher risk of treatment failure.

Pediatric Pharmacology of Desmopressin in Children with Enuresis: A Comprehensive Review

Desmopressin is a synthetic analogue of the natural antidiuretic hormone arginine vasopressin. Over the years, it has been clinically used to manage nocturnal polyuria in children with enuresis. Various pharmaceutical formulations of desmopressin have been commercialized for this indication-nasal spray, nasal drops, oral tablet and oral lyophilizate. Despite the fact that desmopressin is a frequently prescribed drug in children, its use and posology is based on limited pediatric data. This review provides an overview of the current pediatric pharmacological data related to the different desmopressin formulations, including their pharmacokinetics, pharmacodynamics and adverse events. Regarding the pharmacokinetics, a profound food effect on the oral bioavailability was demonstrated as well as different plasma concentration-time profiles (double absorption peak) of the desmopressin lyophilizate between adults and children. Literature about maturational differences in distribution, metabolism and excretion of desmopressin is rather limited. Regarding the pharmacodynamics, formulation/dose/food effect and predictors of response were evaluated. The lyophilizate is the preferred formulation, but the claimed bioequivalence in adults (200 µg tablet and 120 µg lyophilizate), could not be readily extrapolated to children. Prescribing the standard flat-dose regimen to the entire pediatric population might be insufficient to attain response to desmopressin treatment, whereby dosing schemes based on age and weight were proposed. Moreover, response to desmopressin is variable, whereby complete-, partial- and non-responders are reported. Different reasons were enumerated that might explain the difference in response rate to desmopressin observed: different pathophysiological mechanisms, bladder capacity and other predictive factors (i.e. breast feeding, familial history, compliance, sex, etc.). Also, the relapse rate of desmopressin treatment was high, rendering it necessary to use a pragmatic approach for the treatment of enuresis, whereby careful consideration of the position of desmopressin within this treatment is required. Regarding the safety of the different desmopressin formulations, the use of desmopressin was generally considered safe, but additional measures should be taken to prevent severe hyponatremia. To conclude the review, to date, major knowledge gaps in pediatric pharmacological aspects of the different desmopressin formulations still remain. Additional information should be collected about the clinical relevance of the double absorption peak, the food effect, the bioequivalence/therapeutic equivalence, the pediatric adapted dosing regimens, the study endpoints and the difference between performing studies at daytime or at nighttime. To fill in these gaps, additional well designed pharmacokinetic and pharmacodynamic studies in children should be performed.

Discovery of Potent, Selective, and Short-Acting Peptidic V2 Receptor Agonists

The vasopressin analogue desmopressin (desamino-d-arginine⁸ vasopressin, dDAVP, 1) is a potent vasopressin 2 (V₂) receptor (V₂R) agonist approved in many countries for the treatment of diabetes insipidus, primary nocturnal enuresis, nocturia, and coagulation disorders. Since 1 is primarily excreted via the kidneys, an age-related decline in kidney function leads to slower elimination, prolonged antidiuresis, and hyponatremia. In search of novel, potent, selective, and short-acting peptidic V₂R agonists, we synthesized a series of C-terminally truncated analogues of [Val⁴]dDAVP, 2, modified in positions 2, 3, and 7 and/or at the disulfide bridge. The peptides were evaluated for in vitro potency at the human V₂ receptor, selectivity versus the related receptors (human vasopressin 1a receptor, human vasopressin 1b receptor, and human oxytocin receptor), and pharmacokinetic profiles in rodents and other higher species. The truncated analogues show excellent potency at the V₂R, increased systemic clearance, and shorter half-life in rats. Two compounds 19 (c(Bua-Cpa-Thi-Val-Asn-Cys)-Pro-Agm) and 38 (c(Bua-Cpa-Thi-Val-Asn-Cys)-Pro-d-Arg-NEt₂) have been selected for clinical development for nocturia.

Pharmacokinetics of desmopressin administrated as an oral lyophilisate dosage form in children with primary nocturnal enuresis and healthy adults

The population pharmacokinetics of desmopressin in children with nocturnal enuresis and in healthy adults were compared using a 1-compartment model with first-order absorption and first-order elimination. In addition, the model consisted of a number of transit compartments before absorption to describe a lag-time. The model gave an adequate description of adult as well as children data and provided a statistically significant better fit to data than a standard lag-time model. The main difference in the pharmacokinetics between children and adults was the absorption delay. The pharmacokinetic difference was minor and presumably of no clinical relevance.

The Role of Bladder Capacity in Antidiuretic and Anticholinergic Treatment for Nocturnal Enuresis

PURPOSE

We evaluated combination treatment with desmopressin and oxybutynin in patients with enuresis who did not respond to desmopressin monotherapy. Furthermore, we compared 2 methods of estimating bladder capacity and evaluated the ability of these methods to predict the response to desmopressin and oxybutynin.

MATERIALS AND METHODS

A total of 60 children with a mean age +/- SD of 10.6 +/- 3.0 years who had monosymptomatic nocturnal enuresis completed the study. After a 2-week observation period maximal voided volume during free access to fluid intake was determined by a 2-day frequency-volume chart and maximal voided volume after water load was determined on a separate day. Patients then received 20 mug desmopressin intranasally at bedtime during 2 weeks. In nonresponders to desmopressin with less than a 50% decrease in wet nights 5 mg oxybutynin twice daily was added for another 2 weeks.

RESULTS

Of the patients 41 (68%) showed more than 50% decrease in wet nights during the 2-week desmopressin treatment period (4.6 +/- 1.6 to 0.7 +/- 0.8, p <0.001). In desmopressin nonresponders combined treatment with desmopressin and oxybutynin resulted in a further decrease in wet nights (4.0 +/- 1.2 to 1.7 +/- 1.4, p <0.001). Maximal voided volume during free access to fluid intake was significantly higher in desmopressin responders than in nonresponders (244 +/- 111 vs 160 +/- 65 ml, p <0.001). In contrast, maximal voided volume after water load was not significantly different between desmopressin responders and nonresponders.

CONCLUSIONS

The study indicates a role for oxybutynin in combination with desmopressin in children who are not responding to desmopressin monotherapy. Maximal voided volume during free access to fluid intake is a clinically useful predictor of the response to desmopressin but not to oxybutynin.

Morbidity and mortality associated with vasopressin analogue treatment

DDAVP is a drug that should be used with caution for each patient individually. Particular care is needed to avoid fluid overload and rapid fluctuations in sodium concentration. Not only families but physicians as well should be educated and aware of the adverse effects of DDAVP, especially in high risk patients. Extreme caution is needed in children with severe neurological and developmental problems who cannot control their fluid intake themselves. Similarly, caution is needed in patients with hypodipsia and DI who have difficulty in balancing water intake and DDAVP dose. The treatment of DI is water; however, DDAVP is given to avoid a large fluid intake which can result in medullary washout. Frequent home monitoring of body weight and regular determinations of serum sodium may help to disclose the early phase of over-hydration or dehydration. DDAVP therapy should be temporarily interrupted during acute illness, febrile episodes, hot days and other conditions with increased water intake. It should be used with considerable caution in patients with cystic fibrosis, or renal or cardiovascular diseases. In patients with enuresis, it is recommended that DDAVP medication should not be continued for longer than 3 months without stopping for 1 week for full reassessment. Fluid intake should be limited 1 hour before and 8 hours after the dose. Generally, undertreatment with vasopressin analogue is safer than overtreatment. A simple measure to avoid overtreatment is to miss one dose once a week; a rapid onset diuresis ('washout' effect) provides considerable reassurance.

The pharmacokinetics of 400 microg of oral desmopressin in elderly patients with nocturia, and the correlation between the absorption of desmopressin and clinical effect

OBJECTIVE

To investigate the pharmacokinetic profile of oral desmopressin in elderly patients with nocturia, and to analyse any possible correlation between the absorption and clinical effect.

PATIENTS AND METHODS

In all, 32 patients were screened to determine the baseline number of nocturnal voids and the nocturia index; of these, 24 fulfilled the inclusion criteria and were enrolled for a pharmacokinetic evaluation of oral desmopressin 400 microg. A double-blind, randomized, placebo-controlled, crossover-effect evaluation period was then used to test the association between the absorption of desmopressin and pharmacodynamic effect. Serial plasma samples were collected for 8 h for a pharmacokinetic analysis of desmopressin. The pharmacodynamics after an equivalent oral dose before bedtime were assessed by measuring changes in the number of nocturnal voids, time to first nocturnal void and nocturnal diuresis, from placebo to active treatment.

RESULTS

There was a linear relationship between plasma desmopressin at 2 h after dosing and the area under the plasma concentration curve from 0 to infinity (Pearson's rho 0.923, P < 0.001). Women had a significantly higher plasma desmopressin concentration than men (P = 0.0012) and more adverse events. There was no correlation between plasma desmopressin at 2 h after dosing and the within-patient response in any of the effect variables. Generally, the number of nocturnal voids and nocturnal diuresis were half that with placebo. The time to the first nocturnal void was almost doubled compared with placebo.

CONCLUSIONS

There seems to be a relationship between gender, plasma level of desmopressin and the incidence of adverse events. Plasma desmopressin at 2 h after dosing cannot be used to predict the pharmacodynamic response, although desmopressin lowers the nocturnal diuresis and the number of nocturnal voids.

Pharmacokinetics and pharmacodynamics of desmopressin administered orally versus intravenously at daytime versus night-time in healthy men aged 55-70 years

OBJECTIVE

To investigate (1) the pharmacokinetic and pharmacodynamic profiles of desmopressin in men from an age group with a high incidence of nocturia; and (2) circadian variation in the pharmacokinetic parameters.

METHODS

The study had an open, randomised, four-way cross-over design. Desmopressin was administered orally (0.2 mg) and intravenously (2 microg), daytime and night-time, yielding four in-hospital sessions, separated by at least 2 days. Blood samples were taken before and at predetermined time points up to 12 h after dosing. Pharmacokinetic parameters were derived using a two-compartmental model except for AUC(0-->t), which was derived using non-compartmental analysis. Bioavailability was estimated using AUC(0-->t) for the oral and the intravenous periods. Urine, for measurements of volume and osmolality, was collected in predetermined intervals before and until 12 h after dosing.

RESULTS

Fifteen healthy men aged 55-70 years were included in the analysis. The concentration-time curve after 2 microg intravenous desmopressin was best described using a biexponential term. The mean (95% CI) AUC at night was 302 (272-335) pg x h/ml and in the day was 281 (253-312) pg x h/ml. No statistically significant differences were detected between night and day except for terminal half-life, which was 3.1 h at night and 2.8 h in the daytime (P=0.02). After oral desmopressin, concentrations above the limit of quantification (2.5 pg/ml) were only detected in 51% of the samples. Peak plasma concentration (Cmax) was 6.2 (5.1-7.5) pg/ml at night and 6.6 (5.5-7.9) pg/ml in the daytime. Median time to reach Cmax (tmax) was 1.5 (range 1.0-4.1) h at night and 1.5 (range 0.5-3.0) h in the day. The bioavailability was 0.08%. The pharmacodynamic effects of oral and intravenous desmopressin given in the daytime were similar during the first 6 h after dosing. The night-time dosing and daytime intravenous dose resulted in antidiuresis throughout the measuring period, while the effect of the daytime peroral dose receded after 6 h.

CONCLUSION

The pharmacokinetic profile of desmopressin is biexponential. Terminal half-life was longer at night than in the daytime, but the difference is considered too small to be of clinical importance. The plasma levels given by the intravenous dose resulted in a duration of action of 12 h or more. Despite low bioavailability, the pharmacodynamic effects of oral desmopressin were similar in magnitude to those after intravenous dose at night and during the first 6 h after daytime administration.

DIURETIC TREATMENT OF NOCTURNAL ENURESIS: PRELIMINARY RESULTS OF AN OPEN PILOT STUDY

PURPOSE

Since antidiuretic treatment with desmopressin in the evening has proven effective against enuresis, it would not be surprising if diuretic treatment in the afternoon would have similar effects. We are currently testing this in an open pilot investigation.

MATERIALS AND METHODS

A total of 33 children including 12 girls with a mean age +/-SD of 7.6 +/- 2.3 years with monosymptomatic enuresis were recruited from an outpatient primary care setting. Wet and dry nights were recorded for 2 weeks without medication, 2 weeks with 0.4 mg desmopressin orally at night and 2 weeks with 1 mg/kg furosemide 4 to 5 hours before bedtime.

RESULTS

The mean number of wet nights +/-SD during the 3 periods was 10.2 +/- 3.0, 6.7 +/- 4.7 and 7.8 +/- 4.5, respectively. The effects of desmopressin and of furosemide were statistically significant (p <0.0001 and p = 0.001), although the 2 treatments did not differ (p = 0.08). Only 6 children had a complete response (ie greater than 90% reduction in wet nights) to desmopressin and 5 responded to furosemide. Interestingly, 2 children had a clearly better response on furosemide than on desmopressin.

CONCLUSIONS

The treatment of enuresis with diuretic medication in the afternoon may be beneficial but needs to be tested in randomized controlled trials.

Sleep problems in children with common medical disorders

Sleep problems are common in many pediatric medical disorders and complicate management and patient outcomes. A wide range of conditions, including asthma, cystic fibrosis, sickle cell disease, gastroesophageal reflux, neuromuscular diseases, scoliosis, craniofacial abnormalities, obesity, and chromosomal disorders, have various sleep disturbances, including sleep-disordered breathing, ventilatory dysfunction, sleep-onset and sleep maintenance problems, and circadian rhythm disturbances. Given the adverse neurocognitive and physiologic outcomes associated with a deranged night's sleep, it is important for pediatricians to be able to anticipate, recognize, and appropriately manage these problems. This article reviews the known sleep-related problems of a few relatively common pediatric disorders.

Nocturnal enuresis

Nocturnal enuresis is a benign condition, yet needs treatment to relieve the child and parents of the accompanying anxiety and the stigma attached to it. It is defined as normal nearly complete evacuation of the bladder at a wrong place and time at least twice a month after the fifth year of life. The underlying cause of enuresis is functional and various proposed pathophysiological mechanisms like maturational delay, genetics, role of sleep, antidiuretic hormone, and bladder capacity are discussed. These factors have a bearing on the management. As no treatment plan is ideal, various treatment modalities currently available including good supportive care are elaborated and a plan of management discussed.

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.

Evaluation of high concentration intranasal and intravenous desmopressin in pediatric patients with mild hemophilia A or mild-to-moderate type 1 von Willebrand disease

OBJECTIVES

The objective of the study was to evaluate the safety and efficacy of high-concentration intranasal desmopressin (HCIN-DDAVP) 1.5 mg/mL, in patients weighing < or = 50 kg with mild hemophilia A or mild type 1 von Willebrand disease (VWD).

STUDY DESIGN

This was a single-center, nonrandomized, open-label, single-dose trial of HCIN-DDAVP. Nine boys with hemophilia A, 8 girls with mild VWD, and 8 boys with mild VWD were evaluated. HCIN-DDAVP responses were compared with historic IV-DDAVP responses in 13 of the patients.

RESULTS

HCIN-DDAVP administration resulted in statistically significant mean increases in factor VIII procoagulant activity, ristocetin cofactor, and von Willebrand factor antigen levels in each of the 3 study groups. Mean (+/- 1 SD) increase in factor VIII procoagulant activity was 25.7 +/- 11.9 U/dL in mild hemophilia A. Ristocetin cofactor increased 108.5 +/- 53.8 U/dL in girls and 95.8 +/- 36.0 U/dL in boys with mild VWD. Intravenous desmopressin acetate responses were comparable to HCIN-DDAVP responses in patients who received both preparations. Adverse events were mild and resolved without intervention.

CONCLUSION

We conclude that administration of 150 microg of high concentration intranasal desmopressin is safe and effective in patients weighing < or = 50 kg with mild hemophilia A or mild type 1 VWD.

Relationships among nocturnal urinary volume, bladder capacity, and nocturia with and without water load in nonenuretic children

OBJECTIVES

To evaluate the relationships among nocturnal urinary volume (NUV), bladder capacity, and nocturia in nonenuretic children with and without water load.

METHODS

We evaluated 72 healthy nonenuretic volunteers. The NUV and bladder capacity were measured for 2 nights at volunteers' homes with and without water load.

RESULTS

Of the 72 nonenuretic children, 45 (63%) were classified into the large NUV group in which the NUV with water load was more than the upper limit of the 95% confidence interval of NUV in Japanese nonenuretic children, and the other 27 (37%) were classified into the small NUV group. In the large NUV group, 33 (73%) had one or two episodes of nocturia because of water intake, and 12 (27%) did not. The nocturnal bladder capacity in the latter 12 children was significantly larger than that in the former 33, although no significant differences were found in functional bladder capacity and NUV with water intake.

CONCLUSIONS

Most nonenuretic children were able to cope with the physiologic loading of water that would cause bedwetting in enuretic children. After water loading, three quarters of the nonenuretic children were able to awake easily because of the need to urinate with a certain volume of urine in the bladder, and the one quarter who did not awake were able to hold more urine in their bladder in the sleep state.

Oxybutynin, desmopressin and enuresis

PURPOSE

A review of the scarce literature concerning oxybutynin treatment for nocturnal enuresis reveals that its success is greatest when enuresis is combined with daytime incontinence. The renal and bladder related characteristics of children with monosymptomatic enuresis responsive to oxybutynin were evaluated.

MATERIALS AND METHODS

Renal concentrating capacity and functional bladder capacity were compared between 55 dry children who served as controls, and children with monosymptomatic enuresis who responded to desmopressin only (group 1, 27), oxybutynin only (group 2, 11), combination desmopressin and oxybutynin (group 3, 7) or were resistant to all treatment alternatives (group 4, 23).

RESULTS

Renal concentrating capacity was lowest in groups 1 and 3 (939 +/- 147 mOsm./kg. controls, 856 +/- 158 group 1, 1,073 +/- 71 group 2, 762 +/- 119 group 3 and 970 +/- 146 group 4; p <0.01), whereas they had high urinary output (15.4 +/- 73.4 ml./kg. per hour controls, 22.2 +/- 10.2 group 1, 13.5 +/- 4.3 group 2, 21.5 +/- 11.2 group 3 and 15.0 +/- 6.9 group 4; p <0.01). Forced functional bladder capacity of that expected for age was lowest in groups 2 to 4 (107 +/- 43% controls, 88 +/- 43 group 1, 71 +/- 25 group 2, 68 +/- 22 group 3 and 59 +/- 22 group 4; p <0.01).

CONCLUSIONS

Children responding to oxybutynin have small bladders and probably hyperactive detrusors, whereas those responding to desmopressin or who need both drugs to achieve dryness have polyuria.

Enuresis and encopresis: ten years of progress

OBJECTIVE

To review the progress made over the past decade with regard to the treatment of enuresis and encopresis, as well as advances in the understanding of etiological mechanisms.

METHOD

Separate computerized literature (English language only) searches of Medline and PsycINFO databases were conducted under the parameter of enuresis and children-adolescents, as well as encopresis and children-adolescents.

RESULTS

There has been a substantial decrease in published research concerning the use of imipramine to treat enuresis compared with the prior two decades, accompanied by a corresponding increase in the number of papers concerning desmopressin acetate (DDAVP), which has become the primary pharmacological treatment. Genetic studies of large pedigrees have further confirmed the importance of heritable factors. With regard to encopresis, the research has focused primarily on pathophysiological factors related to the colon and anal sphincter.

CONCLUSIONS

The widespread use of DDAVP has been the primary addition to treatment strategies over the past decade. The bell-and-pad method of conditioning, the only major treatment that has enduring benefit after being withdrawn, is the most cost-effective and appears to be underutilized. Research into etiological mechanisms has focused primarily on the mechanism of action of DDAVP and advances in the understanding of genetic factors. Advances in the treatment and etiological understanding of encopresis have been less impressive.

Bladder capacity and renal concentrating ability in enuresis: pathogenic implications

PURPOSE

We compared bladder volume and renal concentrating capacity in dry children and 2 distinct groups of children with enuresis to hypothesize about the pathogenesis of various types of enuresis.

MATERIALS AND METHODS

A total of 55 dry children and 100 with enuresis underwent an overnight thirst provocation test to assess renal concentrating capacity and completed a 2-day voiding chart to assess functional bladder capacity. The enuretic children were subdivided into 27 desmopressin responders and 73 desmopressin nonresponders before study inclusion.

RESULTS

The desmopressin responder group had lower average renal concentrating capacity +/-1 standard deviation than dry children and desmopressin responders (856 +/- 158 mOsm./kg. versus 939 +/- 147 and 962 +/- 151, respectively, p <0.05). Analogously average daytime urine production in the desmopressin responder group was greater than in dry children and desmopressin responders (22.2 +/- 10.2 ml./kg. body weight versus 15.4 +/- 7.3 and 15.3 +/- 7.2, respectively, p <0.01). Average functional bladder capacity expected for age was less in desmopressin nonresponders than in dry children and responders (52.2% +/- 19.9% versus 79.2% +/- 30.4% and 69.5% +/- 25.7%, respectively, p <0.001).

CONCLUSIONS

Desmopressin responders produced larger amounts of less concentrated urine than the other children, while desmopressin nonresponders had smaller bladder capacity than the other groups. These results support the idea that enuretic children who respond favorably to desmopressin treatment have polyuria, whereas children with therapy resistant enuresis have detrusor hyperactivity.

The three systems: a conceptual way of understanding nocturnal enuresis

Childhood nocturnal enuresis has traditionally been regarded as a multifaceted problem with a variety of treatment interventions. This paper proposes a model based on the notion that nocturnal enuresis arises through the ill functioning of one or more of the following three systems - a lack of vasopressin release during sleep; bladder instability; and/or an inability to arouse from sleep to bladder sensations. Clinical signs of each system are outlined and the appropriate treatment intervention for each is discussed. It is argued that addressing nocturnal enuresis in this way will enhance overall treatment effectiveness.

Desmopressin resistant enuresis: pathogenetic and therapeutic considerations

PURPOSE

We tested the role of the bladder in the pathogenesis of desmopressin resistant enuresis by evaluating the influence of urine production on the timing of the enuretic event and the response to anticholinergic medication.

MATERIALS AND METHODS

We gave 33 children with monosymptomatic nocturnal enuresis resistant to the standard 0.4 mg. oral dose of desmopressin 0.4 and 0.8 mg. desmopressin and placebo tablets for 5 nights each in a double-blind crossover fashion. The time of enuresis or nocturia was documented. All 9 children who had at least 1 dry treatment period during the randomized portion of the study then received open label treatment with 0.8 mg. desmopressin. Nonresponders to this regimen and the remainder of the children were offered anticholinergic treatment.

RESULTS

Average time between bedtime and voiding was 5.0, 5.6 and 5.0 hours during the nights with placebo, and 0.4 and 0.8 mg. desmopressin, respectively (p = 0.12). Of the 9 children subsequently treated with 0.8 mg. desmopressin 5 became completely dry. Of the remaining 28 children given anticholinergic treatment 20 responded.

CONCLUSIONS

Antidiuresis does not delay the enuretic event in children with desmopressin resistant enuresis. This finding and the favorable response to anticholinergic medication favor the hypothesis that these children have nocturnal bladder instability. A subgroup of enuretic children responds to high but not normal doses of desmopressin.