Cobalamin-binding capacity of haptocorrin and transcobalamin: age-correlated reference intervals and values from patients.
Unsaturated cobalamin-binding capacity in plasma (P-UBBC) is determined by use of a silica gel (QUSO G32) to separate haptocorrin (P-ApoHC) and transcobalamin (P-ApoTC). The method is sensitive and precise: detection limit 13 pmol/L, interassay coefficients of variation 3% for P-UBBC (mean = 1080 pmol/L), 4% for P-ApoTC (mean = 700 pmol/L) (n = 30). Values for P-UBBC, P-ApoHC, P-ApoTC, and P-TBBC (P-UBBC plus P-cobalamin) determined in a population study of 228 individuals, ages 21-87 years, did not differ by sex. These values increased with age, whereas the cobalamin saturation (P-cobalamin as percentage of P-TBBC) decreased with age. However, these changes were statistically significant but marginal and thus not clinically important. We therefore suggest using combined reference intervals (central 95 percentiles) for all age groups: 500-1200 pmol/L for P-UBBC, 90-275 pmol/L for P-ApoHC, 400-930 pmol/L for P-ApoTC, 850-1600 pmol/L for P-TBBC, and 20-50% for cobalamin saturation. Results for 277 inpatients show high P-ApoHC in myeloproliferative disorders or acute nonlymphatic leukemia, whereas P-ApoTC concentrations are high in some patients with lymphoproliferative disorders or autoimmune diseases.
Department of Internal Medicine and Hematology, Gentofte Hospital, Hillerød, Denmark.
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Nexø
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D014155:Transcobalamins / Q000032:analysis* / Q000502:physiology
D014155:Transcobalamins