In many people, low vitamin B12 levels reflect reduced dietary intake, and supplementation is a common way deficiencies related to diet are addressed. In other cases, low B12 arises from absorption problems, such as pernicious anaemia or other gastrointestinal conditions, where increasing oral intake alone does not reliably correct levels and deficiency is managed differently.
Because different mechanisms can lead to low B12, the underlying cause is often considered rather than interpreting the result in isolation. Persistently low levels, or results seen alongside abnormalities in other markers, are often reviewed in more detail to clarify the reason for deficiency.
Vitamin B12 and folate are closely linked in red blood cell production and DNA synthesis, and abnormalities in one can influence interpretation of the other. For this reason, folate status and full blood count indices are commonly reviewed alongside B12 results, particularly where deficiency is suspected. In some situations, changes in folate can partially mask underlying B12 deficiency, which is why these markers are often considered together.
Low vitamin B12 is commonly flagged for review by a GP.
Adjusted Calcium 
