Do high vitamin B12 levels in children matter?

Abstract:

Vitamin B12 levels are often recommended for children. Locally, we note many children have B12 levels above the upper limit of normal (771 ng/L1). We receive frequent advice requests from GPs regarding high B12 and have found a paucity of evidence to guide our response.

A Turkish retrospective study of 40 children with B12>1000 pg/mL concluded that high levels are usually benign, but some may develop leukaemia later.2 This was based on a leukaemia diagnosis in 2 out of 40 children within 3 years. They stated that in children with high B12 ‘all known disease should be excluded first by haematological, biochemical and radiological investigation’.

These children were recruited from a specialist haematology service and had mostly been referred from other paediatric clinics. The pre-test probability of haematological malignancy was likely to be higher than in our local population and might not be related to …