Can elevated vitamin B12 levels cause elevated liver function tests (LFTs)?

Elevated Vitamin B12 as a Cause of Elevated Liver Function Tests

Elevated vitamin B12 levels do not cause elevated liver function tests (LFTs); rather, elevated B12 is often a consequence of liver disease that causes LFT abnormalities. 1, 2

Relationship Between Vitamin B12 and Liver Disease

• Hypervitaminosis B12 (elevated serum B12 levels) has been associated with liver diseases including cirrhosis and acute-phase hepatitis 1
• In alcoholic liver disease, B12 leaks from damaged liver tissue into the circulation, resulting in elevated plasma B12 levels while liver tissue B12 concentration decreases 2
• The elevation of serum B12 occurs due to disruption of B12 binding and storage by transcobalamin in the liver, causing B12 to leak into the bloodstream 2

Diagnostic Implications

• Elevated B12 levels can serve as a marker of liver disease severity rather than a cause of liver dysfunction 2
• When evaluating abnormal liver tests, the American College of Radiology recommends considering various causes based on the pattern of elevation (hepatocellular vs. cholestatic) 3
• Common causes of mild aminotransferase elevations include NAFLD, alcohol-induced liver disease, drug-induced liver injury, and viral hepatitis - not vitamin B12 elevation 3

Clinical Approach to Elevated LFTs

• Initial evaluation of abnormal liver tests should include a detailed history, medication inventory, and physical examination 3
• When assessing elevated liver enzymes, clinicians should determine if the pattern is predominantly hepatocellular (elevated ALT/AST) or cholestatic (elevated ALP) 3
• For mild aminotransferase elevations, ultrasound is recommended as a first-line investigation tool 3

Vitamin B12 as a Biomarker

• Persistently elevated vitamin B12 levels (>1,000 pg/mL on two measurements) have been associated with solid tumors, hematologic malignancy, and increased risk of cardiovascular death 4
• Elevated serum tryptase and/or vitamin B12 levels are commonly observed in myeloproliferative variants of hypereosinophilia, particularly in myeloid neoplasms with PDGFRA fusion gene 3
• In patients receiving parenteral nutrition, elevated B12 levels are common but do not correlate with liver pathology or hepatic chemistries 5

Important Clinical Considerations

• When evaluating abnormal liver tests, the pattern of abnormality (hepatocellular vs. cholestatic) and the magnitude of elevation are more important diagnostic indicators than B12 levels 3
• Elevation of plasma B12 accompanied by a lowering of holotranscobalamin II distribution may serve as an index of liver disease severity 2
• The interpretation of abnormal liver chemistries must always be considered in the clinical context of the individual patient 3

Pitfalls to Avoid

• Don't attribute elevated LFTs to high vitamin B12 levels; instead, consider elevated B12 as a potential marker of underlying liver disease 1, 2
• Avoid focusing solely on B12 levels when evaluating liver dysfunction; a comprehensive approach considering the pattern of liver enzyme elevation is essential 3
• Don't overlook common causes of elevated LFTs such as NAFLD, alcohol-induced liver disease, and medication effects when encountering elevated B12 levels 3