Vitamin B12 deficiency is not uncommon and is a significant public health concern. Vitamin B12 deficiency should be suspected in all patients with unexplained anaemia and/or neurological symptoms. The elderly, neuropsychiatric and psychiatric patients, and those adhering to a vegetarian diet are amongst the groups at risk.

Accurate diagnosis is not trivial. Symptoms can be diffuse, haematological markers alone (blood count, cell morphology) may under-diagnose. The total serum B12 assay, for long the mainstay of clinical diagnosis, is known to give misleading results. Other recently introduced or suggested laboratory markers have recognised limitations.

Currently there is no consensus, nor generally applicable guidelines, for the definition and diagnosis of vitamin B12 deficiency. There exists a need for improvement in current approaches.

This web-site is for those who wish to find out more about this field and in particular the use of Active-B12 (holotranscobalamin) as an indicator of vitamin B12 status.