THE VITAMIN B12 AND FOLATE PATHOLOGY INVESTIGATION
THE INVESTIGATION OF ERRORS IN PATHOLOGY TESTS
FOR VITAMIN B12 AND FOLATE DEFICIENCY
BY MEANS OF MEDICAL EXPERIMENTS
B12 AND FOLATE INFORMATION
B12 EXPERT OPINION
B12 Expert Opinion
Diagnosis
Oh and Brown, reference DA01:

The diagnosis of vitamin B12 deficiency has traditionally been based on low serum vitamin B12 levels, usually less than 200 pg per mL (150 pmol per L), along with clinical evidence of disease. However, studies indicate that older patients tend to present with neuropsychiatric disease in the absence of hematologic findings.5,6 Furthermore, measurements of metabolites such as methylmalonic acid and homocysteine have been shown to be more sensitive in the diagnosis of vitamin B12 deficiency than measurement of serum B12 levels alone.3,10-14

 

Snow, reference DA02:
At one time, the diagnosis of a deficiency of vitamin B12 or folate was considered to be relatively straightforward. As knowledge has accumulated, the limitations of such tests as serum vitamin level measurements and the Schilling test have become apparent. With the development of newer tests, atypical and subclinical deficiency states have been recognized. In this review, available tests used in the diagnosis of vitamin B12 and folate deficiency are discussed, and a rational approach to the diagnosis of these deficiency states is presented.

 

Nexo et al, reference DA03:
The assays aimed to answer the question: does this patient suffer from cobalamin deficiency, include analysis of P--cobalamins and analyses of the metabolites that accumulate upon cellular cobalamin deficiency, P--methylmalonate and P--homocysteine. P--cobalamins or especially a fraction of P--cobalamins, P--TC cobalamins are markers for latent cobalamin deficiency. An increased concentration of P--methylmalonate that decreases upon injection of cobalamin indicates overt metabolic cobalamin deficiency. The same holds for P--homocysteine but this analysis is less specific than P--methylmalonate.

 

Clarke et al, reference DA04:

 

Herbert, reference EA08:

 

Klee, reference DA06:

 

Holleland et al, reference DA07:

 

Bolann et al, reference DA08:

 

Elin and Winter, reference DA09:

 

Walsh reference BA01:

 

Norris, reference BA02:

Blood B12 Level: Not a Reliable Measure of B12 Adequacy

A sB12 level below the normal range indicates that B12 levels are becoming depleted. However, as described below, a sB12 level in the normal range does not ensure that B12 levels are healthy. Unfortunately, medical practitioners still use serum B12 to evaluate function, even of vegans.

 

Virology Down Under, reference BB01:

Diagnosis

  • Many cases are seen that have a decreased serum B12 with a normal haematological profile and possibly normal clinical findings
  • Test for methylmalonic acid in the serum as an indicator of vitB12 deficiency
  • Test for homocysteine to check folate levels

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