Hi and welcome to Healthcaremagic. Thank you for your query. I am Dr. Rommstein and I will try to help you as much as I can. Liver transplantation is extensive surgical procedure and electrolyte imbalance is common complication. Liver is organ that excretes hormones and enzymes required for sodium absorption and here some imbalance may occur after transplantation. Second cause may be kidney insufficiency and third too low salt intake. In every case,sodium can be replaced intravenously and extensive tests are required to identify exact cause. I am sure doctors will find it. In general, this is not big deal. I hope I have answered you query. If you have any further questions you can contact us. Kindly regards. Wish you a good health.