Huntington Disease (HD) is a neurodegenerative disease with an autosomal dominant inheritance pattern characterized by late onset, jerking movements, difficulty with reasoning/cognition and change in personality. The exact mechanism of the pathology is not known but current research is focusing on the hypothalamus and the endocrine system. Magnetic resonance spectroscopy (MRS) provided evidence that HD mice had elevated metabolite (esp. sodium) concentrations in their blood, which led Dr. Janet Dubinsky to believe hypernatremia and resulting sodium retention may be the mechanism of brain shrinkage in HD mice. Subsequently, an experiment was designed to observe and analyze the cause and effect of sodium retention in mice with Huntington disease. A change in the metabolic activity of transgenic mice was observed upon the onset of HD, characterized by increased overall water consumption, decrease in urine osmolarity and increase in plasma osmolality.