Clinical implications of high cobalamin blood levels for internal medecine

Purpose. - The high incidence of cobalamin (vitamin B12) deficiency results in frequent dosages of this vitamin in a department of internal medicine may reveal paradoxically high blood levels of cobalamin. The objective of the study was to estimate underlying diseases and potential diagnostic relevance of high cobalamin blood levels in internal medicine. Methods. - A retrospective study was conducted, including in-patients from December 2005 to July 2006 presenting high cobalamin blood levels, as determined with our laboratory normal values (200-950 pg/mL). Results. - High cobalamin blood level is not unusual (18.5% of all dosages) and, most of time, it is associated with one or several diseases, among which acute and chronic liver diseases (often of alcoholic origin), various neoplasias, malignant hemopathies (myelodysplasia, myeloproliferative diseases, multiple myeloma), renal insufficiency and transient hematologic abnormalities (neutrophilic hyperleucocytosis, hypereosinophilia). Vitamin B12 supplementation and chronic myeloid leukemia represent less than 5% of all hypervitaminemia. There is no correlation between the level of cobalamin blood level and the number of underlying diseases for each patients. However, very high cobalamin blood levels (>1275 pg/mL) are significantly associated to malignant hemopathies (p<0.05). It is noteworthy that most of diagnosed neoplasia were unknown and at a non-metastatic stage. Conclusion. - Very high cobalamin blood levels are significantly associated to malignant hemopathies among the population of a department of internal medecine. Referent laboratory should actively advertise the numerous diseases involved with high cobalamin blood levels. (C) 2007 Elsevier Masson SAS. Tous droits reserves.