Relationships between low serum cobalamin concentrations and methlymalonic acidemia in cats

J Vet Intern Med. 2009 May-Jun;23(3):472-5. doi: 10.1111/j.1939-1676.2009.0308.x. Epub 2009 Apr 21.


Background: Serum cobalamin concentrations below reference range are a common consequence of gastrointestinal disease in cats. Serum cobalamin <or= 100 ng/L is associated with methylmalonic acidemia.

Objectives: To determine the prevalence of cobalamin deficiency, defined by elevated serum methylmalonic acid (MMA), in cats with serum cobalamin <or= 290 ng/L, and the optimum serum cobalamin concentration to predict cobalamin deficiency in cats. SAMPLE SET: Residual serum samples (n = 206) from cats with serum cobalamin <or= 290 ng/L.

Methods: Retrospective, observational study. Serum cobalamin and folate were measured with automated assays. Serum MMA was determined by gas chromatography-mass spectrometry. Cobalamin deficiency was defined as serum MMA > 867 nmol/L. Sensitivity and specificity of serum cobalamin concentrations <or=290 ng/L for detecting MMA > 867 nmol/L were analyzed using a receiver-operator characteristic curve.

Results: There was a negative correlation between serum cobalamin and MMA concentrations (Spearman's r=-0.74, P < 0.0001). The prevalence of MMA >or= 867 nmol/L in cats with serum cobalamin <or= 290 ng/L was 68.4%. Serum cobalamin <or= 160 ng/L had a 74% sensitivity and 80% specificity for detecting MMA > 867 nmol/L. No significant difference in serum folate concentrations was detected between affected and unaffected cats.

Conclusions and clinical importance: Elevated MMA concentrations, suggesting cobalamin deficiency, are common in cats with serum cobalamin <or= 290 ng/L. Cobalamin deficiency is clinically significant, and supplementation with parenteral cobalamin is recommended for cats with gastrointestinal disease and low serum cobalamin concentrations.

MeSH terms

  • Animals
  • Cat Diseases / blood*
  • Cats
  • Methylmalonic Acid / blood*
  • Retrospective Studies
  • Sensitivity and Specificity
  • Vitamin B 12 / blood*
  • Vitamin B 12 Deficiency / blood
  • Vitamin B 12 Deficiency / veterinary


  • Methylmalonic Acid
  • Vitamin B 12