Jeg har B12 på rundt 300 pmol/L. Legen sier det er fint, men har så mange symptomer.... Har jeg ikke mangel da?

30.07.2019

Jeg har B12 på rundt 300 pmol/L. Legen sier det er fint, men har så mange symptomer.... Har jeg ikke mangel da?

Jeg har B12 på rundt 300 pmol/L. legen sier det er fint, men har så mange symptomer.... Har jeg ikke mangel da?

Referanseområdet for vitamin B12er 170 - 650 pmol/L

Svar; Med B12 på rundt 300 uten tilskudd kan du ha symptomatisk mangel. Dvs at verdien er «bra» men symptomene på mangel er til stede. Flere av de norske pasientene som har vært i Amsterdam har blitt betydelig bedre med hyppige injeksjoner.

Hvorfor er det slik?

There are several reasons serum B12 is not low in all patients with B12 deficiency.

 In part, this relates to the distribution of B12 on the 2 major plasma B12 binding proteins. Normally, the major fraction (70% to 90%) of circulating B12 is bound to HC, which is unavailable for immediate delivery to cells.

 The other 10% to 30% is bound to transcobalamin (TC), the functional B12 transport protein. Consequently, if levels of the HC-bound fraction are conserved, the total serum B12 level may lie within the normal reference range, despite lowered levels of the important TC-bound fraction.

 An extreme example of this is seen in a B12-deficient patient with normal serum B12 levels who has an underlying myeloproliferative disease with high HC levels. 

In almost 50% of patients with low vitamin B12 levels, levels of the biochemical markers, MMA and Hcy, were found to be normal, and these patients had no hematologic or neurologic response to B12 replacement therapy, suggesting that thelow B12 values were false positive results.

Serum B12 levels are usually normal in functional B12 deficiency, resulting from exposure to nitrous oxide, which chemically inactivates the methylcobalamin at the active site of the methionine synthase during its catalytic cycle.

Serum B12 levels are also usually normal in TC deficiency, and inborn errors of cobalamin metabolism.

 Conversely, serum B12 levels may be low in the presence of normal tissue B12 in vegetarians, in subjects taking megadoses of ascorbic acid, in inherited "benign" HC deficiency,and in a substantial propor- tion of patients with megaloblastic anemia resulting from folate deficiency (30%).

https://incan-mexico.org/wp_hematologia/wp-content/uploads/deficiencia-de-B12.pdf?fbclid=IwAR0Y6CCba5e1mvQ076fMaxjbxbUovLzOYGZEasviKsu7U_S4cXLDr-MK14Y