Night-time polyuria and urine hypo-osmolality in enuretics identified by nocturnal sequential urine sampling--do they
A Pomeranz1, G Abu-Kheat, Z Korzets
1Clinic of Nocturnal Enuresis, Pediatric Nephrology Outpatient Clinic and the Department of Pediatrics, Meir General Hospital, Kfar-Saba, Israel.
Insights
A subgroup of children with nocturnal enuresis may have a relative deficiency in antidiuretic hormone (ADH) at night, leading to increased urine production. Early morning urine osmolality testing can identify these children for targeted treatment.
Area of Science:
- Pediatric Nephrology
- Endocrinology
- Urology
Background:
- Nocturnal enuresis affects many children, with varying underlying causes.
- Understanding the pathophysiology is crucial for effective treatment strategies.
Purpose of the Study:
- To investigate potential differences in urine osmolality and production in enuretic children compared to non-enuretic controls.
- To identify a subgroup of enuretics with possible nocturnal antidiuretic hormone (ADH) deficiency.
- To evaluate the efficacy of DDAVP treatment in identified subgroups.
Main Methods:
- Sequential measurement of urine osmolality and volume at 3-hour intervals overnight in enuretic and non-enuretic children.
- Comparison of urinary parameters between groups.
- Treatment of enuretic children with intranasal DDAVP for 6 months.
Main Results:
- A subgroup of 17 enuretic children (ADH-negative) showed significantly lower urine osmolality and increased urine production between 01:00 and 04:00 compared to ADH-positive enuretics and controls.
- DDAVP treatment showed similar response rates in both ADH-negative and ADH-positive enuretics.
- ADH-negative enuretics achieved a response to DDAVP more quickly.
Conclusions:
- Nocturnal polyuria, potentially due to relative nocturnal ADH deficiency, may underlie enuresis in a specific subgroup of children.
- Sequential overnight urine monitoring can identify this subgroup.
- Early identification may lead to faster treatment response with DDAVP.
Abstract:
Early morning urine osmolality was tested in two urinary specimens, one taken immediately upon awakening and the other approximately 30 min thereafter, in 52 enuretic and 15 non-enuretic children. In a follow-up study, using the same study population, urine osmolality and volume were measured sequentially at 3-h intervals at 19.00, 22.00, 01.00, 04.00 and 07.00 h. Thereafter, all enuretics were treated by intranasal DDAVP for a 6-month period. There were no differences in urinary osmolality between enuretic and non-enuretic children when comparing the two early morning specimens. Nor were there any differences between groups in urine osmolalities at 19.00, 01.00 and 07.00 h. In contrast, at 04.00 h, urine osmolality was significantly lower in 17 of 52 enuretics [designated as ADH-negative (ADH-)] compared to the remaining enuretics [designated as ADH-positive (ADH+)] and non-enuretic children (610 +/- 251 vs 995 +/- 195 and 1089 +/- 195 mosmol/kg H2O, respectively, p < 0.05). This decreased osmolality was paralleled by an increase in urine production during the time period 01.00-04.00 (83 +/- 24 vs 52 +/- 18 and 45 +/- 22 ml, respectively, p < 0.05). At the end of the 6-month period of DDAVP treatment, the percentage response was similar between the ADH- and ADH+ enuretics (79% vs 75%). However, the time taken to achieve a response was quicker in the ADH- subjects. These data suggest the existence of a subgroup of enuretics whose underlying pathophysiology is the development of nocturnal polyuria probably due to a relative night-time ADH deficiency. Nocturnal sequential monitoring of urinary osmolality, as described above, allows identification of this subgroup.
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