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Therefore, serum B 12 values above the cut-off point of deficiency do not necessarily confirm adequate B 12 status. [2] For this reason, elevated serum homocysteine over 15 micromol/L and methylmalonic acid (MMA) over 0.271 micromol/L are considered better indicators of B 12 deficiency, rather than relying only on the concentration of B 12 in ...
Serum vitamin B 12 is a medical laboratory test that measure vitamin B 12 only in the blood binding to both transcobalamins. [1] Most of the time, 80–94% of vitamin B 12 in the blood binds to haptocorrin , while only 6–20% is binds to transcobalamin ll. [ 2 ] Only transcobalamin ll is "active" and can be used by the body. [ 1 ]
Deficiencies of vitamins B 6, B 9 and B 12 can lead to high homocysteine levels. [2] Vitamin B 12 acts as a cofactor for the enzyme methionine synthase (which forms part of the S-adenosylmethionine (SAM) biosynthesis and regeneration cycle). Vitamin B 12 deficiency prevents the 5-methyltetrahydrofolate (5-MTHF) form of folate from being ...
Homocysteine levels typically are higher in men than women, and increase with age. [ 15 ] [ 16 ] Common levels in Western populations are 10 to 12 μmol/L, and levels of 20 μmol/L are found in populations with low B-vitamin intakes or in the elderly (e.g., Rotterdam, Framingham).
Over time, a deficiency of B12 can cause problems with balance, confusion, depression, poor memory and possibly dementia, and it can even cause permanent damage to the nervous system, Somers says.
References range may vary with age, sex, race, pregnancy, [10] diet, use of prescribed or herbal drugs and stress. Reference ranges often depend on the analytical method used, for reasons such as inaccuracy, lack of standardisation, lack of certified reference material and differing antibody reactivity. [11]
In women aged between 19 and 64 years, the mean serum vitamin B 12 concentration was slightly lower than men (298 pmol/L), with 3.3% having low vitamin B 12 concentrations < 150 pmol/L. [162] In Germany, a national survey in 1998 was conducted in 1,266 women of childbearing age.
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