Unexpected high plasma cobalamin : proposal for a diagnostic strategy.

Area of Science:

• Clinical Biochemistry
• Internal Medicine
• Oncology

Background:

• Over 8% of patients tested for vitamin B12 deficiency present with unexpectedly high plasma cobalamin levels.
• Clinical guidelines for interpreting elevated vitamin B12 are lacking.
• High plasma cobalamin is an unspecific but significant marker for underlying diseases.

Purpose of the Study:

• To review known disease associations with high plasma cobalamin.
• To propose a clinical interpretation strategy for elevated vitamin B12.
• To emphasize the importance of considering critical diagnoses first.

Main Methods:

• Literature review of studies associating high plasma cobalamin with various diseases.
• Analysis of potential pathogenic mechanisms, including binding protein concentrations.
• Development of a clinical interpretation strategy based on current evidence.

Main Results:

• Significant associations found between high plasma cobalamin and cancer, liver diseases, and kidney diseases.
• Other diagnostic entities also show associations with elevated vitamin B12.
• Pathogenesis is multifactorial, potentially involving transcobalamin and haptocorrin.

Conclusions:

• A clinical strategy for interpreting high plasma cobalamin is proposed, prioritizing life-threatening conditions.
• High cobalamin should prompt consideration of cancer, followed by liver and kidney diseases.
• Further research into the pathogenic mechanisms of elevated vitamin B12 is warranted.