Background:
Aquaporin 2 (AQP2) is an arginine vasopressin (AVP) sensitive water channel that mediates transmembrane water transport in the collecting ducts and several investigators have examined urinary AQP2 instead of plasma AVP in patients with nocturnal enuresis. We previously reported day-night ratio of urinary aquaporin 2 reflected enuresis severity. To investigate whether morning urinary aquaporin 2 could be used as an early biomarker of predict of desmopressin therapeutic effect in polyuria type nocturnal enuresis.
Methods:
We measured urinary AQP2/creatinine (AQP2/Cr) in polyuria type nocturnal enuresis children treated with desmopressin acetate oral disintegrating tablet (dDAVP ODT).The morning urine AQP2 was measured before and within 8 weeks after desmopressin treatment. Patients were classified into an elevated AQP2/Cr group (elevated group) and a decreased AQP2/Cr group (decreased group) before and after desmopressin treatment.
Results:
53 polyuria type nocturnal enuresis children (28 boys, 23 girls) were included in this study. Median age of starting desmopressin treatment was 8.2 years, and the median observation period was 1.3 years. Among the 47 children obtained more than six months observation period, 38 were classified into the elevated group and 9 were into the decreased group. There was no difference in the age at the start of desmopressin treatment and the observation period between the two groups. The number of patients who could finish enuresis treatment at the time of last follow-up were fifty (39.5%) in the elevated group and two (22.2%) in the decreased group. The rate of patients who could finish desmopressin treatment during observation periods in the elevated group was significantly higher than those of the decreased group (91.9% vs 44.4%; p < 0.01).
Conclusions:
This study suggests that the morning AQP2/Cr is useful biomarker to predict response of desmopressin treatment in enuretic patients with nocturnal polyuria.
