Nocturnal polyuria is related to absent circadian rhythm of glomerular filtration rate.
OBJECTIVE
Monosymptomatic nocturnal enuresis is frequently associated with nocturnal polyuria and low urinary osmolality during the night. Initial studies found decreased vasopressin levels associated with low urinary osmolality overnight. Together with the documented desmopressin response, this was suggestive of a primary role for vasopressin in the pathogenesis of enuresis in the absence of bladder dysfunction. Recent studies no longer confirm this primary role of vasopressin. Other pathogenetic factors such as disordered renal sodium handling, hypercalciuria, increased prostaglandins and/or osmotic excretion might have a role. So far, little attention has been given to abnormalities in the circadian rhythm of glomerular filtration rate. We evaluated the circadian rhythm of glomerular filtration rate and diuresis in children with desmopressin resistant monosymptomatic nocturnal enuresis and nocturnal polyuria.


METHODS
We evaluated 15 children (9 boys) 9 to 14 years old with monosymptomatic nocturnal enuresis and nocturnal polyuria resistant to desmopressin treatment. The control group consisted of 25 children (12 boys) 9 to 16 years old with monosymptomatic nocturnal enuresis without nocturnal polyuria.


RESULTS
Compared to the control population, children with nocturnal polyuria lost their circadian rhythm not only for diuresis and sodium excretion but also for glomerular filtration rate.


CONCLUSIONS
Patients with monosymptomatic nocturnal enuresis and nocturnal polyuria lack a normal circadian rhythm for diuresis and sodium excretion, and the circadian rhythm of glomerular filtration rate is absent. This absence of circadian rhythm of glomerular filtration rate and/or sodium handling cannot be explained by a primary role of vasopressin, but rather by a disorder in circadian rhythm of renal glomerular and/or tubular functions.
De Guchtenaere
A
A
Paediatric Uro-nephrological Center, University Hospital Gent, Gent, Belgium.
Vande Walle
C
C
Van Sintjan
P
P
Raes
A
A
Donckerwolcke
R
R
Van Laecke
E
E
Hoebeke
P
P
Vande Walle
J
J
D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D002940:Circadian Rhythm / Q000502:physiology*; D003894:Deamino Arginine Vasopressin / Q000627:therapeutic use; D004231:Diuresis / Q000502:physiology*; D004351:Drug Resistance; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D053206:Nocturnal Enuresis / Q000150:complications / Q000503:physiopathology*; D009994:Osmolar Concentration; D011141:Polyuria / Q000150:complications / Q000188:drug therapy / Q000503:physiopathology*; D011446:Prospective Studies; D012016:Reference Values; D012720:Severity of Illness Index; D012964:Sodium / Q000378:metabolism; D018709:Statistics, Nonparametric; D014563:Urodynamics / Q000502:physiology; D014667:Vasopressins / Q000652:urine
D014667:Vasopressins; D012964:Sodium; D003894:Deamino Arginine Vasopressin