Hepatology is a branch of medicine that studies the liver and its various disorders. Hepatologists, or doctors that specialize in hepatology, today feel that there is a growing problem that is on the horizon. This entity is called NAFLD or non-alcoholic fatty liver disease. This is a spectrum of disorders of the liver that ranges from a fatty liver (also called steatohepatitis) to a more severe form called NASH or non-alcoholic steatohepatitis. The difference between the two is the amount of injury sustained by the liver cells that ultimately causes liver failure and the need for a liver transplant.
This entire spectrum of NAFLD is the manifestation in the liver of the so called “metabolic syndrome”. Underlying common cause of the metabolic syndrome is insulin resistance seen as obesity, type 2 diabetes and lipid abnormalities. Obesity is a growing problem in the Western Hemisphere with approximately 30 to 40 percent of adults and 17 percent of children in the obese category (BMI > 30. Normal BMI is below 25) in the US. It is estimated that NASH will be the number one reason for liver transplantation worldwide in the next 10 to 20 years, with an estimated 20 % of all NAFLD patients with NASH. Today, there are more than 2 million patients with NASH in the US, all potentially requiring a liver transplant in the next few years. It is currently the third most common reason to require a liver transplant, only after hepatitis C and alcohol related cirrhosis.
What this also means is that all potential liver donors, whether deceased or live, are also vulnerable to having fatty liver. It is a well established fact that fatty livers do not do well if used for transplantation. There is a higher incidence of these livers not working at all, a phenomenon called primary graft non-function or that they have poor long term function. One way to avoid this problem is to be selective when assessing a potential donor. A liver biopsy to assess for the amount of fat in the liver cells is sometimes required. If there is more than 30 % steatosis or amount of fat in the liver, it is generally not used for transplantation. This puts an additional burden on the already critical shortage of livers that are available out there for transplantation.
Studies have shown overall good results after liver transplantation for NASH. Compared to hepatitis C or alcoholic cirrhosis, patients with NASH tend to have a higher incidence of death from cardiovascular causes and infections. The same studies also show recurrence of NASH in a third of the recipients of the new liver after transplantation, but very few will progress to requiring another transplant. Interestingly, about a third of recipients in the non-NASH category also have been shown to develop NAFLD in 1 to 3 years after transplantation.