Non-alcoholic fatty liver disease (NAFLD) is a name that is given to a range of liver disorders associated with the presence of too much fat in the liver. Steatosis is a mild form of fatty liver. In some patients with steatosis, inflammation of the liver may occur with resultant hepatitis called non-alcoholic steatohepatitis (NASH).
Risk Factors
Risk factors for NAFLD include obesity, diabetes, insulin resistance and hyperlipidemia.
How Common is NAFLD:
NAFLD is considered the most common liver disease in the western world affecting 20-30% of the population, rising to 70-90% of the obese population and approximately 50% of the diabetic population. In 2012 nearly 70% of US adults were overweight, with 35% of adults in the obese category. In the UK, according to the 2012 Health Survey for England, approximately one quarter of adults are obese.
NAFLD is estimated to occur in approximately 30% of adults in the United States. NASH is present in 2-5% of individuals. With the current obesity epidemic, these percentages continue to increase.
Patients with NAFLD, especially those with mild steatosis, rarely have symptoms. Patients may present in one of three ways:
- A mild increase in liver size may be noted on physical exam, warranting further testing.
- An elevation of liver enzymes may be noted on routine laboratory testing.
- The presence of fat in the liver may be an incidental finding on an imaging study such as an ultrasound or CT scan which is obtained for an unrelated reason.
The amount of liver fat can now be quantified with HepaFat-Scan. Early detection of steatosis (liver fat) facilitates the early diagnosis and intervention before liver damage may become irreversible.
NAFLD Linked to Diabetes and Liver Cancer:
Steatosis has also been linked to reduced effectiveness of antiviral treatments and has been implicated in the development of type 2 diabetes. Non-alcoholic fatty liver disease (NAFLD) is an independent predictor of type 2 diabetes according to a study presented at the European Association for the Study of the Liver International Liver Congress 2014.
In a retrospective study (3074 subjects) conducted in Japan, people with NAFLD had nearly three times the risk of developing diabetes than people without the condition, according to Hajime Yamazaki, MD, of Teine Keijinkai Hospital in Sapporo, Japan, and colleagues. At the > 10 year follow up, he found that 16.1% of the 728 patients with NAFLD had developed type 2 diabetes, versus only 3.1% of the remaining 2346 NAFLD negative patients. The odds ratio for the NAFLD association was 6.05 (P<0.001). A multivariate analysis adjusted for confounders such as age, sex, BMI, family history of diabetes and dyslipidemia and the odds ratio remained significant at 2.82 (P<0.001). Moreover, improvements in NAFLD reduced the risk of diabetes over about an 11-year follow-up, Yamazaki told an oral session. Ultrasound follow up analysis at >10 years showed that 110 of the 728 subjects with NAFLD had an improvement in their NAFLD and the incidence of type 2 diabetes in this group was 6.4% vs 17.8% in the group with no improvement in NAFLD. Dr Yamazaki stated that “The clinical message is that it is important to reduce fatty liver to prevent diabetes”.
Recent research suggests a strong association between hepatic steatosis and hepatocellular carcinoma (HCC) in the absence of cirrhosis, indicating that steatosis may be a causative factor for HCC.
A French study (5671 subjects) also presented at the European Association for the Study of the Liver International Liver Congress 2014 found that NAFLD is an independent predictor of carotid atherosclerosis. C-IMT, carotid plaques and Framingham risk scores were all significantly higher in the 1871 subjects with NAFLD vs the 3800 without the disease. All were independent of age, sex, BMI, hypertension and tobacco use. Dr Raluca Pais, MD, PhD from of Pitié-Salpêtrière Hospital in Paris stated that “Patients at risk for CVD should probably be screened for fatty liver, regardless of the transaminase levels, because NAFLD is an independent predictor of cardiovascular risk, beyond traditional risk factors like metabolic syndrome”.
As the evidence against fatty liver mounts, researchers and clinicians are embarking on studies that require the measurement of liver fat content so that it can be correlated with health risks and other clinical parameters such as age and overall weight gain or loss. Biopsy is often unacceptable for such studies and hence non-invasive methods are required. HepaFat-Scan® provides such a solution.