Persistent polyuria after posterior urethral valves.
OBJECTIVE
To assess urinary concentrating ability, urine production and glomerular filtration rates in a cohort of boys with previously treated posterior urethral valves.


METHODS
Urinary concentrating capacity was assessed in 51 boys aged 5.4-9.9 years with previously treated posterior urethral valves. They all completed urinary frequency/volume charts, permitting calculation of 24 h urine volumes. The osmolality of an overnight urine collection was measured and, if < 800 mOsm/kg (n = 40), an intramuscular injection of desamino-cys-1-8-D-arginine vasopressin was given to determine the maximum concentrating ability. The glomerular filtration rate (GFR) was estimated from the plasma clearance of 51Cr-ethylenediamine tetra-acetic acid following a single intravenous injection.


RESULTS
The mean 24 h urine volume was 1025 +/- 448 (SD) mL. The mean overnight urine flow rate was 28.4 +/- 17.9 mL/h. Urinary concentrating capacity was impaired (< 800 mOsm/kg) in 30 (59%) of the boys and < 300 mOsm/kg in eight (16%). The mean GFR was 81 +/- 38 mL/min/1.73 m2SA. Significant correlations were noted between the GFR, the maximum urine concentration and the 24 h urine volume.


CONCLUSIONS
Persistent polyuria after valve ablation occurs in boys with posterior urethral valves. This has implications both in terms of urinary continence and on-going renal impairment.
Department of Urology, Hospitals for Sick Children, London, UK.
M D
MD
Dinneen
P G
PG
Duffy
T M
TM
Barratt
P G
PG
Ransley
D017115:Catheter Ablation; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D007671:Kidney Concentrating Ability; D008297:Male; D009994:Osmolar Concentration; D011141:Polyuria / Q000209:etiology* / Q000503:physiopathology; D014521:Urethra / Q000002:abnormalities*; D014554:Urination