Enuresis subtypes based on nocturnal hypercalciuria: a multicenter study.
OBJECTIVE
Desmopressin may not be effective for nocturnal enuresis associated with polyuria and hypercalciuria. Nighttime hypercalciuria in an enuretic population from 5 centers and its correlation with nighttime polyuria were verified.


METHODS
A total of 450 enuretic patients (278 males, 172 females, mean age 9.7 years) were evaluated with 72-hour micturition charts, urinalysis, serum creatinine and osmolarity, diurnal and nocturnal electrolytes with fractional Na+ and K+ urinary excretion, and nocturnal (4 a.m.) plasma vasopressin. Creatinine electrolytes and osmolarity were measured in daytime (8 a.m. to 8 p.m.) and nighttime (8 p.m. to 8 a.m.) urine volumes. Patients were divided into group 1 with nocturnal polyuria and group 2 without nocturnal polyuria. Hypercalciuria was defined as urinary calcium-to-urinary creatinine ratio greater than 0.21. Statistic evaluation was performed using chi-square, Pearson correlation and ANOVA tests.


RESULTS
Nighttime polyuria was demonstrated in 292 bedwetters (65% group 1). Nocturnal hypercalciuria was present in 179 of the 450 children (39.7%), including 125 in group 1 (42.8%) and 54 in group 2 (34.2%), which was statistically significant (chi-square p = 0.008, Pearson correlation test r = 0.157). Daytime calciuria was not statistically modified in either group (group 1 p = 0.054, group 2 p = 0.56). Adrenocorticotropic hormone (ADH) was normal in 18.5% and low in 81.5% of enuretics with nocturnal hypercalciuria. ADH levels and nocturnal hypercalciuria significantly correlated (p = 0.003, r = 0.148). Conversely, the group 2 patients had normal ADH levels.


CONCLUSIONS
Nocturnal hypercalciuria has a pivotal role in nocturnal enuresis, as it is significantly associated with low ADH levels and nocturnal polyuria. A new classification of nocturnal enuresis subtypes based on nighttime calciuria levels is mandatory to address treatment properly.
D000293:Adolescent; D000324:Adrenocorticotropic Hormone / Q000097:blood; D002118:Calcium / Q000652:urine*; D002648:Child; D002940:Circadian Rhythm / Q000502:physiology; D003404:Creatinine / Q000097:blood; D003894:Deamino Arginine Vasopressin / Q000627:therapeutic use; D003937:Diagnosis, Differential; D004573:Electrolytes / Q000652:urine; D004775:Enuresis / Q000145:classification* / Q000188:drug therapy / Q000652:urine; D005260:Female; D006801:Humans; D008297:Male; D011141:Polyuria / Q000175:diagnosis* / Q000652:urine; D014667:Vasopressins / Q000097:blood
D004573:Electrolytes; D014667:Vasopressins; D000324:Adrenocorticotropic Hormone; D003404:Creatinine; D003894:Deamino Arginine Vasopressin; D002118:Calcium