You need to be tested

[Biblos]

You need to be tested for intrinsic factor to determine if you have a B12 deficiency

[Poppet11]

Nonsense.

[Gambit62 Administrator]

Lack of Intrinsic Factor - generally due to the presence of Intrinsic Factor Antibodies - which is part of the testing for a diagnosis of Pernicious Anaemia - is one cause of B12 deficiency

There are other things that can lead to a B12 deficiency, including a lack of B12 in your diet or gastric surgery, some medicines.

Intrinsic factor is one of the things that is involved in the processes that the body uses to metabolise B12 but it is far from being the only thing and hence far from being the only cause.

B12 deficiency can be detected through whole serum, active B12 tests and by its impact on some other chemicals in the blood. There isn't a test that is really accurate enough to replace diagnosis of B12 deficiency based on symptoms - and how you respond to B12 supplementation.