Differential Diagnosis for Elevated ALT with Otherwise Normal Liver Function Studies

• Single most likely diagnosis
  • Fatty liver disease: This is the most common cause of elevated ALT in the absence of other liver function abnormalities, often associated with obesity, diabetes, and metabolic syndrome.
• Other Likely diagnoses
  • Muscle injury: Elevated ALT can also be seen in conditions that cause muscle damage, such as muscle dystrophy or recent intense exercise, due to the presence of ALT in muscle tissue.
  • Medication-induced liver injury: Certain medications, like statins, can cause an elevation in ALT without affecting other liver function tests.
  • Viral hepatitis (acute or chronic): Although other liver function tests might be expected to be abnormal, early or mild cases of viral hepatitis can present with isolated ALT elevation.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Wilson's disease: A genetic disorder leading to copper accumulation in the liver, which can cause liver damage and elevated ALT. Early diagnosis is crucial for treatment.
  • Alpha-1 antitrypsin deficiency: A genetic disorder that can lead to liver disease and elevated liver enzymes, including ALT.
  • Autoimmune hepatitis: Although it often presents with other abnormal liver function tests, early or mild cases might only show elevated ALT.
• Rare diagnoses
  • Celiac disease: Can cause elevated liver enzymes, including ALT, due to malabsorption and liver injury.
  • Thyroid dysfunction: Both hypothyroidism and hyperthyroidism can lead to elevated ALT, although this is less common.
  • Hemochromatosis: A genetic disorder causing iron overload, which can lead to liver damage and elevated ALT, typically in conjunction with other signs of iron overload.