Low holotranscobalamin II is the earliest serum marker for subnormal vitamin B12 (cobalamin) absorption in patients with AIDS
✍ Scribed by Victor Herbert; Warren Fong; Veronica Gulle; Tracy Stopler
- Book ID
- 102698290
- Publisher
- John Wiley and Sons
- Year
- 1990
- Tongue
- English
- Weight
- 721 KB
- Volume
- 34
- Category
- Article
- ISSN
- 0361-8609
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✦ Synopsis
In AIDS, as previously found in pernicious anemia (PA), the earliest serum marker of subnormal vitamin B, , (cobalamin) absorption, and therefore of negative B, , balance, is low serum holotranscobalamin II (holo-TC II; B,,-TC II) despite normal total serum B, , level, normal serum homocysteine, and normal classic (oral free radio-B,,) Schilling test. This may be accompanied by subtle and insidious damage to hematopoietic, immunologic, neuropsychiatric, nutritional and alimentary systems, confirmed by correction on therapeutic trial with B, , therapy. Our studies suggest such selective B,, deficiency occurs in about half of the HIV-1 infected, in part due to frequent depression of B, , absorption by HIV-1 attack on the gastric mucosa and/or opportunistic infection attack on the small bowel, and in part due to a telescoping of the continuum of the stages of negative B, , balance in relation to damage to B, , delivery by the infective and/or systemic disease process. In AIDS, when total serum B, , is normal despite tissue depletion of B,,, if the classic Schilling test does not reveal subnormal food B, , absorption, the food Schilling test does. We hypothesize that DNA-synthesizing cells of the hematopoietic, immunologic, neurologic and other systems which have surface receptors solely for holo-TC II, and which have low B, , stores, rapidly become dysfunctional due to B, , deficiency when holo-TC II is low, while cells (such as liver cells) which also have surface receptors for holohaptocorrin (B,,-haptocorrin) remain &,-replete. We believe this to be another example of the concept of selective nutrient deficiency in one cell line but not another.