diagnosis of non-alcoholic fatty liver disease
Patients with nonalcoholic fatty liver disease are often asymptomatic and commonly discovered as an incidental biochemical abnormality (elevate liver AST:ALT) or during thoracic and abdominal imaging for reasons other than liver symptoms.
- patients usually have increased levels of transaminases, with alanine aminotransferase (ALT) levels exceeding those of aspartate aminotransferase (AST) (AST:ALT ratio <0.8)
- this is useful to differentiate hepatic steatosis from NAFLD and alcoholic liver injury (high AST:ALT ratio)
- this change tend to reverse (alanine aminotransferase levels fall) as hepatic fibrosis progresses. Hence steatohepatitis patients with advanced disease may present with relatively normal alanine aminotransferase levels
- some patients may complain of right upper quadrant pain, jaundice, and pruritus (1,2)
A careful history should be obtained in order to help in the diagnosis of NAFLD:
- alcohol intake to rule out alcohol induced fatty liver disease
- previous lipid profiles
- type 2 diabetes in patients and their families, past results for fasting glucose or HbA1c
- to identify competing aetiologies for hepatic steatosis (e.g. - medication, parenteral nutrition, Wilson's disease, severe malnutrition etc) (1,2)
Explore diet, physical activity, and change in weight (usually an increase, such as 40 lb [18 kg] over two to three years.
Assessment for associated conditions (e.g., diabetes, hypertension, hyperlipidemia, obesity, sleep apnoea) should be carried out (1).
Enquire about any family history of cardiovascular and metabolic disorders, and chronic liver disease (1).
Physical examination is typically normal (some patients may have elevated blood pressure, central obesity, and hepatosplenomegaly) (1).
Note:
- it is important to point out that majority of NAFLD patients will be overweight or obese, asymptomatic, and have normal liver function test results
- NICE note that (3):
- identifying NAFLD in higher-risk groups
- be aware that non-alcoholic fatty liver disease (NAFLD) is more common in people who have:
- type 2 diabetes or
- metabolic syndrome
- take an alcohol history to rule out alcohol-related liver disease
- do not use routine liver blood tests to rule out NAFLD
- be aware that NAFLD is a risk factor for type 2 diabetes, hypertension and chronic kidney disease
- be aware that in people with type 2 diabetes, NAFLD is a risk factor for atrial fibrillation, myocardial infarction, ischaemic stroke and death from cardiovascular causes
- diagnosing NAFLD in children and young people
- offer a liver ultrasound to test children and young people for NAFLD if they:
- have type 2 diabetes or
- metabolic syndrome and do not misuse alcohol
- refer children with suspected NAFLD to a relevant paediatric specialist in hepatology in tertiary care
- diagnose children and young people with NAFLD if: ultrasound shows they have fatty liver and other suspected causes of fatty liver have been ruled out
- offer liver ultrasound to retest children and young people for NAFLD every 3 years if they:
- have a normal ultrasound and
- have type 2 diabetes or metabolic syndrome and
- do not misuse alcohol
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