Aim:
To determine the association between urine osmolality in patients with primary monosymptomatic enuresis (PME) and their response to desmopressin. We hypothesized that pretreatment morning urine osmolality is higher in PME patients with desmopressin treatment failure compared to cases with partial or complete initial success.
Methods:
This was a prospective case-controlled study which included 332 patients with enuresis seen in our outpatient clinic between October 2017 and February 2019. Patient workup included symptom checklist, frequency voiding diary, kidney and bladder ultrasound scan, uroflow, urine analysis and culture, urine Ca/creatinine, and first-morning urine osmolality. Patients <5 years of age, with secondary enuresis, and those who did not show at the follow-up visit were excluded. Oral desmopressin lyophilisate was recommended to all patients with PME and normal bladder capacity. After one month of therapy, initial success was assessed according to ICCS. After tests for normality of distribution, the difference of mean urine osmolality between patients with treatment failure and success was analyzed using the unpaired two-sample t-test.
Results:
There were 38 patients with PME who received desmopressin and were followed for treatment success. There were 8 patients with initial success categorized as none and all were boys. A partial or complete response to desmopressin was seen in 30 patients of whom 17 were boys (57%). There was no difference in mean age between groups, with 6.0±1.1 and 7.0±1.8 years for failure and desmopressin response, respectively. Mean urine osmolality was statistically significantly higher in patients with treatment failure (916±150 mOsm/kg) compared to patients with partial or complete initial success (790±184 mOsm/kg), with p=0.042.
Conclusion:
For PME patients with high pretreatment morning urine osmolality, an alternative treatment to desmopressin should be considered because of the significantly higher risk of treatment failure.
