Treatment of the polydipsia-hyponatremia syndrome with urea.
OBJECTIVE
The polydipsiahyponatremia syndrome is difficult to control in patients with severe mental illness, and there is no established effective therapeutic approach. We investigate the effect of oral daily intake of large amounts of urea to prevent hyponatremic episodes.


METHODS
Seven patients were treated during 4 to 18 months with urea (0.3-0.9 g/kg/day). Five of these patients had schizophrenia. Body weight variation between morning and evening was determined before and during the course of therapy in 5 patients. The dose of urea was increased if morning serum sodium level (SNa) was lower than 132 mmol/L.


RESULTS
Urea therapy increased mean +/- SD morning SNa (from 127.5 +/- 3.4 mmol/L before initiation of urea treatment to 136.5 +/- 2.4 mmol/L during the second month of urea treatment; p < .01) and mean +/- SD urine osmolality (from 86 +/- 39 mOsm/kg H(2)O to 159 +/- 58 mOsm/kg H(2)O; p < .05), probably without changes in water intake or urine volume excretion as attested by the level of urinary creatinine concentration. Mean +/- SD body weight variation decreased from 4.5% +/- 1.0% before initiation of urea treatment to 2.8% +/- 1.0% during the second month of urea treatment (p < .05). Two patients stopped urea treatment after 1 year and subsequently developed symptomatic hyponatremia.


CONCLUSIONS
These preliminary data show that urea appears to be an effective therapeutic approach for the polydipsiahyponatremia syndrome.
Verhoeven
Anne
A
Department of Psychiatry, Titeca Hospital, Brussels, Belgium.
Musch
Wim
W
Decaux
Guy
G
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D001835:Body Weight / Q000187:drug effects; D002940:Circadian Rhythm / Q000187:drug effects; D015897:Comorbidity; D003401:Creatine / Q000652:urine; D004326:Drinking / Q000187:drug effects*; D004334:Drug Administration Schedule; D006801:Humans; D007010:Hyponatremia / Q000188:drug therapy* / Q000453:epidemiology / Q000652:urine; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012559:Schizophrenia / Q000188:drug therapy / Q000453:epidemiology; D012565:Schizophrenic Psychology; D013577:Syndrome; D016896:Treatment Outcome; D014508:Urea / Q000494:pharmacology / Q000627:therapeutic use*; D014556:Urine / Q000502:physiology; D014869:Water Intoxication / Q000517:prevention & control
D014508:Urea; D003401:Creatine