MRI changes during water loading in patients with polydipsia and intermittent hyponatremia.
OBJECTIVE
Patients with polydipsia and intermittent hyponatremia have greater ventricle-brain ratios (VBRs) than matched patients without polydipsia and intermittent hyponatremia and normal subjects. Unlike previous studies, this study controlled for the impact of water loading when examining the volume of intracranial structures.


METHODS
Under controlled conditions, eight male schizophrenic patients with polydipsia and intermittent hyponatremia were first assigned to either normal fluid intake or oral water loading and then the alternative condition the following day. Magnetic resonance imaging (MRI) volumetric measurements were made with the use of a standardized protocol.


RESULTS
During water loading, total VBR and lateral ventricle volume significantly decreased by 13.1% and 12.6%, respectively. A strong association between change in serum sodium concentration and change in VBR was noted across conditions.


CONCLUSIONS
These findings indicate that 1) water loading does not account for the diminished brain volume observed in patients with polydipsia and intermittent hyponatremia in previous studies, and 2) hyponatremia can significantly alter brain morphology on MRI.
Leadbetter
R A
RA
Clinical Studies Unit, Western State Hospital, Staunton, Va., USA. robert.leadbetter@wl.com
Shutty
M S
MS
Elkashef
A M
AM
Kirch
D G
DG
Spraggins
T
T
Cail
W S
WS
Wu
H
H
Bilder
R M
RM
Lieberman
J A
JA
Wyatt
R J
RJ
D000328:Adult; D001921:Brain / Q000033:anatomy & histology*; D002552:Cerebral Ventricles / Q000033:anatomy & histology; D004326:Drinking / Q000502:physiology*; D006801:Humans; D007010:Hyponatremia / Q000097:blood / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D008297:Male; D009994:Osmolar Concentration; D012559:Schizophrenia / Q000097:blood / Q000175:diagnosis; D012565:Schizophrenic Psychology; D012964:Sodium / Q000097:blood; D014869:Water Intoxication / Q000097:blood / Q000175:diagnosis*; D014882:Water-Electrolyte Balance / Q000502:physiology
D012964:Sodium