Influence of cobalamin deficiency compared with that of cobalamin absorption on serum holo-transcobalamin II
| Autor: | Angel F. Remacha, M. Pilar Sardà, Ralph Carmel, Xinke Chen |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Male
medicine.medical_specialty Malabsorption Homocysteine Radioimmunoassay Medicine (miscellaneous) Ileum macromolecular substances Absorption (skin) Cobalamin chemistry.chemical_compound Transcobalamin Schilling test Internal medicine Anemia Pernicious polycyclic compounds medicine Humans pernicious anemia Transcobalamins Nutrition and Dietetics medicine.diagnostic_test Chemistry Vitamin B 12 Deficiency Middle Aged medicine.disease Vitamin B 12 Endocrinology medicine.anatomical_structure Case-Control Studies Female |
| Zdroj: | The American Journal of Clinical Nutrition. 81:110-114 |
| ISSN: | 0002-9165 |
| DOI: | 10.1093/ajcn/81.1.110 |
| Popis: | BACKGROUND Cobalamin attached to transcobalamin II (TC II), known as holo-TC II, is the active cobalamin fraction taken up by tissues. Holo-TC II is also the form in which absorbed cobalamin enters the circulation from the ileum. Therefore, holo-TC II has been proposed variously as a marker of cobalamin adequacy, cobalamin absorption, or both, including even its advocacy as a surrogate Schilling test. Such claims carry conflicting diagnostic implications because metabolic adequacy and absorption are not identical. OBJECTIVE The objective was to examine metabolic and absorptive influences on holo-TC II. DESIGN Treated patients with pernicious anemia (PA), who have abnormal absorption but a normal metabolic status, were chosen as the model to differentiate between the effects of the 2 cobalamin-related characteristics. Serum holo-TC II and indexes of cobalamin metabolism in 23 treated patients were compared with those of 6 untreated PA patients (abnormal absorption and metabolic status) and 33 control subjects (normal absorption and metabolic status). RESULTS Holo-TC II, which correlated directly with cobalamin and inversely with homocysteine, was significantly higher in treated PA patients in metabolic remission than in untreated PA patients (74 +/- 59 compared with 9 +/- 6 pmol/L) and was significantly lower than in control subjects (105 +/- 58 pmol/L), although the latter difference was small and the values overlapped greatly. CONCLUSIONS Metabolic cobalamin status is a major determinant of serum holo-TC II. Absorption status may have mild influence as well, although other explanations remain possible. Serum holo-TC II cannot be used clinically to diagnose cobalamin malabsorption because of overlap with normal values. The influences on holo-TC II are complex and require careful analysis. |
| Databáze: | OpenAIRE |
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