Biomaterial Database

Detection of vitamin B12 deficiency in older people by measuring vitamin B12 or the active fraction of vitamin B12, holotranscobalamin. 2007

Robert Clarke, and Paul Sherliker, and Harold Hin, and Ebba Nexo, and Anne Mette Hvas, and Joern Schneede, and Jacqueline Birks, and Per M Ueland, and Kathleen Emmens, and John M Scott, and Anne M Molloy, and John Grimley Evans

Clinical Trial Service Unit, University of Oxford, Oxford, United Kingdom. robert.clarke@ctsu.ox.ac.uk

BACKGROUND Impaired vitamin B(12) function and decreased vitamin B(12) status have been associated with neurological and cognitive impairment. Current assays analyze total vitamin B(12) concentration, only a small percentage of which is metabolically active. Concentrations of this active component, carried on holotranscobalamin (holoTC), may be of greater relevance than total vitamin B(12). METHODS We compared the utility of serum holoTC with conventional vitamin B(12) for detection of vitamin B(12) deficiency in a population-based study of older people, using increased methylmalonic acid (MMA) concentrations as a marker of metabolic vitamin B(12) deficiency in the overall population (n = 2403) and in subsets with normal (n = 1651) and abnormal (n = 752) renal function. RESULTS Among all participants, 6% had definite (MMA >0.75 micromol/L) and 16% had probable (MMA >0.45 micromol/L) metabolic vitamin B(12) deficiency. In receiver operating characteristic curves for detection of definite vitamin B(12) deficiency, holoTC had a greater area under the curve (AUC) compared with vitamin B(12) in all participants (0.85 vs 0.76; P <0.001) and in subsets with normal (AUC: 0.87 vs 0.79; P <0.001) and abnormal (AUC: 0.85 vs 0.74; P = 0.002) renal function. Similar findings were observed for detection of moderate vitamin B(12) deficiency. Whereas the positive predictive value for both holoTC and vitamin B(12) was greater for detection of probable than definite vitamin B(12) deficiency, both tests were associated with more false-positive than true-positive test results. CONCLUSIONS HoloTC has a modestly superior diagnostic accuracy compared with conventional vitamin B(12) for the detection of vitamin B(12) deficiency, but neither test can be recommended to screen asymptomatic populations.

UI	MeSH Term	Description	Entries
D008875	Middle Aged	An adult aged 45 - 64 years.	Middle Age
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000368	Aged	A person 65 years of age or older. For a person older than 79 years, AGED, 80 AND OVER is available.	Elderly
D014155	Transcobalamins	A group of carrier proteins which bind with VITAMIN B12 in the BLOOD and aid in its transport. Transcobalamin I migrates electrophoretically as a beta-globulin, while transcobalamins II and III migrate as alpha-globulins.	Cobalamin-Binding Protein,Transcobalamin,Transcobalamin II,Vitamin B 12-Binding Protein,Vitamin B 12-Binding Proteins,Vitamin B12-Binding Protein,Cobalamin-Binding Proteins,Cobalophilin,Haptocorrin,Holo-Transcobalamin II,R-Binder,Transcobalamin (I),Transcobalamin I,Transcobalamin III,Vitamin B 12 Binder,Vitamin B12-Binding Proteins,B12-Binding Protein, Vitamin,Cobalamin Binding Protein,Cobalamin Binding Proteins,Holo Transcobalamin II,Protein, Cobalamin-Binding,Protein, Vitamin B12-Binding,Proteins, Cobalamin-Binding,Proteins, Vitamin B12-Binding,R Binder,Vitamin B 12 Binding Protein,Vitamin B 12 Binding Proteins,Vitamin B12 Binding Protein,Vitamin B12 Binding Proteins
D014805	Vitamin B 12	A cobalt-containing coordination compound produced by intestinal micro-organisms and found also in soil and water. Higher plants do not concentrate vitamin B 12 from the soil and so are a poor source of the substance as compared with animal tissues. INTRINSIC FACTOR is important for the assimilation of vitamin B 12.	Cobalamin,Cyanocobalamin,Cobalamins,Eritron,Vitamin B12,B 12, Vitamin,B12, Vitamin
D014806	Vitamin B 12 Deficiency	A nutritional condition produced by a deficiency of VITAMIN B 12 in the diet, characterized by megaloblastic anemia. Since vitamin B 12 is not present in plants, humans have obtained their supply from animal products, from multivitamin supplements in the form of pills, and as additives to food preparations. A wide variety of neuropsychiatric abnormalities is also seen in vitamin B 12 deficiency and appears to be due to an undefined defect involving myelin synthesis. (From Cecil Textbook of Medicine, 19th ed, p848)	Deficiency, Vitamin B 12,Deficiency, Vitamin B12,Vitamin B12 Deficiency,Deficiencies, Vitamin B12,Vitamin B12 Deficiencies
D015203	Reproducibility of Results	The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.	Reliability and Validity,Reliability of Result,Reproducibility Of Result,Reproducibility of Finding,Validity of Result,Validity of Results,Face Validity,Reliability (Epidemiology),Reliability of Results,Reproducibility of Findings,Test-Retest Reliability,Validity (Epidemiology),Finding Reproducibilities,Finding Reproducibility,Of Result, Reproducibility,Of Results, Reproducibility,Reliabilities, Test-Retest,Reliability, Test-Retest,Result Reliabilities,Result Reliability,Result Validities,Result Validity,Result, Reproducibility Of,Results, Reproducibility Of,Test Retest Reliability,Validity and Reliability,Validity, Face