Nonalcoholic Fatty Liver Disease

Implications for Clinical Practice and Health Promotion

Bethany Croke, FNP-BC; Deborah Sampson, FNP-BC

Disclosures

Journal for Nurse Practitioners. 2012;8(1):45-50. 

In This Article

Diagnosis

Many differential diagnoses cause elevated liver enzymes and must be ruled out. Alcoholic fatty liver disease (AFLD) usually presents with hepatomegaly and right upper quadrant tenderness; history reveals alcohol intake that exceeds 20 g/day (1.5 standard alcoholic drinks/day) for women and 30 g/day (2 standard alcoholic drinks/day) for men. The laboratory AST/ALT ratio is typically > 2, as well.

An autoimmune cause should be considered if the patient presents with symptoms of type 1 diabetes, Graves disease, ulcerative colitis, vasculitis, or Sjorgen's disease. Risk factors for viral hepatitis, such as illicit injection drug use, high-risk sexual behavior, and transfusions, should lead to evaluation for these diseases. Evidence of viral hepatitis usually can be identified from serology test results. Medications and toxins can also cause elevated liver enzymes, and symptoms vary based on the particular agent. Therefore, initial diagnostic tests to rule out other diseases and to assess the liver include a complete blood count, antinuclear antibody, erythrocyte sedimentation rate, liver function tests, viral hepatitis serology, and ultrasound of the liver.

Diagnosis of NAFLD has historically been made based on 3 criteria: abnormal hepatic histology, minimal alcohol consumption, and absence of viral hepatitis. If NAFLD is suspected in the presence of elevated liver enzymes, an imaging study should be ordered to detect the presence of fatty infiltrates. Ultrasound is typically used because of its lack of radiation exposure and its cost effectiveness compared to computed tomography scan and magnetic resonance imaging (MRI), respectively. MRI may be preferred despite its cost because of its superior sensitivity in detecting fat, especially since central obesity may result in poor ultrasound findings.

Finally, a liver biopsy is performed to confirm the findings and to assess disease status and potential progression to NASH. Liver biopsy is the only modality that accurately differentiates between fatty liver and NASH. Liver biopsy can also differentiate between NAFLD and alcoholic liver disease because histology findings in AFLD usually show greater cellular inflammation and hepatocellular injury.

In children, waist circumference typically correlates with the severity of NAFLD. Pediatric cases also have a different histological presentation compared to adults. Children show increased inflammation and fibrosis in the portal area, rather than in the lobules, and more severe fatty infiltration. Efforts are made to avoid invasive and risky procedures (liver biopsy) in children, but even the most highly-sensitive MRIs cannot accurately differentiate between fatty liver and NASH.

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