Nocturnal polyuria is related to 24-hour diuresis and osmotic excretion in an enuresis population referred to a tertiary center

PURPOSE

Primary nocturnal enuresis is a heterogeneous disorder, causing a mismatch between overnight diuresis volume and functional bladder capacity. Despite increasing insights in pathogenesis, lack of efficacy of the available treatments is a major problem. We evaluated characteristics of bladder volume and diuresis rate in patients with nocturnal enuresis referred to a tertiary enuresis center.

MATERIALS AND METHODS

Noninvasive screening including maximal voided volume, 24-hour circadian rhythm of diuresis and osmotic excretion from 1,000 consecutive patients.

RESULTS

Of the patients referred as having monosymptomatic nocturnal enuresis 32% were subsequently classified as having nonmonosymptomatic nocturnal enuresis. Differences in bladder volume and nocturnal diuresis characteristics between the monosymptomatic nocturnal enuresis and nonmonosymptomatic nocturnal enuresis groups were minimal.

CONCLUSIONS

The most common observation is a nocturnal diuresis volume greater than maximal voided volume, which in both groups can be caused by nocturnal polyuria or small bladder volume for patient age. The most striking observation is that the positive correlation between nocturnal diuresis volume rate and nocturnal osmotic excretion and 24-hour fluid intake is significantly higher than with the inversed urinary osmolality overnight, which is not only unexpected based on the theory of the primary suppression of vasopressin levels overnight, but also points to a more important role for nutritional and fluid intake than accepted, if not in the primary pathogenesis, then at least in therapy resistance.

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.