Differential Diagnosis for Elevated ALT and Low Alk Phos

• Single Most Likely Diagnosis
  • Viral hepatitis (e.g., hepatitis A, B, or C): This is a common cause of elevated alanine transaminase (ALT) levels, and alkaline phosphatase (alk phos) can be normal or low in the acute phase of the illness.
• Other Likely Diagnoses
  • Alcoholic liver disease: While often associated with elevated alk phos, early stages or mild cases might present with isolated ALT elevation and relatively low alk phos.
  • Non-alcoholic fatty liver disease (NAFLD): Similar to alcoholic liver disease, NAFLD can cause elevated ALT levels, and alk phos might be normal or slightly elevated, but not significantly high.
  • Medication-induced liver injury: Certain medications can cause liver damage, leading to elevated ALT levels. Alk phos might not be significantly elevated, especially if the injury is primarily hepatocellular.
• Do Not Miss Diagnoses
  • Acute bile duct obstruction: Although alk phos is often elevated in bile duct obstruction, in the very early stages, it might not be significantly elevated, and ALT can be markedly increased due to hepatocellular injury.
  • Ischemic hepatitis: This condition, caused by reduced blood flow to the liver, can lead to a significant elevation in ALT with minimal elevation in alk phos.
  • Wilson's disease: A genetic disorder leading to copper accumulation in the liver, which can cause liver damage and elevated ALT levels. Alk phos can be normal or low, especially in the early stages.
• Rare Diagnoses
  • Alpha-1 antitrypsin deficiency: A genetic disorder that can cause liver disease and might present with elevated ALT and normal or low alk phos.
  • Autoimmune hepatitis: Although typically associated with a broad range of liver enzyme abnormalities, some cases might present with predominant ALT elevation and relatively low alk phos.
  • Hemochromatosis: A condition of iron overload that can lead to liver damage. While often associated with elevated liver enzymes, the pattern can vary, and ALT might be more significantly elevated than alk phos in some cases.