Medical Professionals FAQ
Are there any problems with the current test to determine B12 status in patients with suspected deficiency ?
The competitive-binding luminescence assay (CBLA) has replaced microbiologic and radioisotope-dilution assays in the past decade. A recent report showed that the current test produces false normal results in 26%, 22% and 35% of the serum samples tested. See also here.
How effective is the current test to diagnose Pernicious Anaemia – the Anti-Intrinsic Factor Antibody ?
If positive, the test has a high positive predictive value (>95%) for the presence of pernicious anaemia, with a concurrent low false positive rate (1–2%) i.e. a high specificity.
However, IFAB is positive in 40–60% of cases, i.e., low sensitivity, and the finding of a negative IFAB assay does not therefore rule out pernicious anaemia (hereafter referred to as AbNegPA).
Once a patient receives replacement therapy injections to correct any cobalamin deficiency patients make a complete recovery don’t they ?
Nobody is able to explain this or the fact that some patients will have extremely low serum B12 status and yet experience none of the symptoms associated with B12 deficiency. More importantly some patients will need more frequent replacement therapy injections than others – though nobody is able to explain why this is so.
Testing B12 during treatment
Control of the vitamin B12 status during treatment is considered to be of little use. During vitamin B12 injections, transcobalamin en haptocorrin are fully saturated with vitamin B12. Therefore, serum and Active B12 values cannot be used to ascertain the effect of treatment. The patient’s symptoms should be the guideline for basing treatment. After the loading dose, a maintenance dose can be determined based on the symptoms.
What evidence is there that there are serious problems with the way in which B12 deficiency is being diagnosed ?
Two recent papers show that the current test used to determine B12 status in patients is flawed.
See the paper in the library – Problems with Diagnosing and Treating Vitamin B12 Deficiency and Pernicious Anaemia – the paper is fully referenced.
Are the current markers used to investigate Pernicious Anaemia reliable ?
No – In a study of 70 consecutive patients with pernicious anaemia only 45 (64%) had very low cobalamin levels (i.e. under 100pg/ml). Anaemia was absent in 13 (19%) and macrocytosis was absent in 23 (33%)
What is the problem with the current treatment regime used to treat Pernicious Anaemia ?
Some members manage perfectly well on an injection every three months, but a great many more need more frequent injections. If their doctor refuses then patients will source alternative treatment including purchasing injections from internet pharmacies. 10% of our members use Methylcobalamin which isn’t licensed in the UK or North America.
What is wrong with the current test to determine whether the patient’s deficiency is due to Pernicious Anaemia ?
Why does the society believe there are problems with the way in which B12 deficiency is diagnosed ?
Around 14% of our members waited over ten years for a diagnosis. Around 20% waited over two years – and that’s a long time when you are ill.
What is the society doing about this ?
We are also working with clinical researchers to explain how these problems can be solved.