title: Effects of dilutional hyponatremia on brain organic osmolytes and water content in patients with cirrhosis.
abstract: In advanced cirrhosis there is a reduction in the brain concentration of many organic osmolytes, particularly myo-inositol (MI). Hyponatremia could theoretically aggravate these changes as a result of hypo-osmolality of the extracellular fluid. The aim of this study was to determine the effects of hyponatremia on brain organic osmolytes and brain water content in cirrhosis. Brain organic osmolytes, measured by (1)H-magnetic resonance spectroscopy, and brain water content, as estimated by magnetization transfer ratio (MTR) and measurement of brain volume were determined in 14 patients with dilutional hyponatremia, 10 patients without hyponatremia, and eight healthy subjects. Patients with hyponatremia had remarkable lower levels of MI compared with values in nonhyponatremic patients and healthy subjects. Brain MI levels correlated directly with serum sodium and osmolality. Serum sodium was the only independent predictor of low brain MI levels. Serum sodium also correlated directly with other brain organic osmolytes, such as choline-containing compounds, creatine/phosphocreatine, and N-acetyl-aspartate. By contrast, brain glutamine/glutamate levels were higher in patients with cirrhosis compared with values in healthy subjects and correlated with plasma ammonia levels but not with serum sodium or osmolality. No significant differences were found in MTR values and cerebral volumes between patients with and without hyponatremia. In conclusion, dilutional hyponatremia in cirrhosis is associated with remarkable reductions in brain organic osmolytes that probably reflect compensatory osmoregulatory mechanisms against cell swelling triggered by a combination of high intracellular glutamine and low extracellular osmolality. These findings may be relevant to the pathogenesis of encephalopathy in hyponatremic patients.
authors.affiliation: Liver Unit, Hospital Clínic, Barcelona, Spain.
authors.forename: Tea
authors.initials: T
authors.lastname: Restuccia
authors.forename: Beatriz
authors.initials: B
authors.lastname: Gómez-Ansón
authors.forename: Mónica
authors.initials: M
authors.lastname: Guevara
authors.forename: Carlo
authors.initials: C
authors.lastname: Alessandria
authors.forename: Aldo
authors.initials: A
authors.lastname: Torre
authors.forename: M Elena
authors.initials: ME
authors.lastname: Alayrach
authors.forename: Carlos
authors.initials: C
authors.lastname: Terra
authors.forename: Marta
authors.initials: M
authors.lastname: Martín
authors.forename: Magda
authors.initials: M
authors.lastname: Castellví
authors.forename: Lorena
authors.initials: L
authors.lastname: Rami
authors.forename: Aitor
authors.initials: A
authors.lastname: Sainz
authors.forename: Pere
authors.initials: P
authors.lastname: Ginès
authors.forename: Vicente
authors.initials: V
authors.lastname: Arroyo
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000378:metabolism*; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000150:complications / Q000378:metabolism*; D008103:Liver Cirrhosis / Q000150:complications / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water