Carbohydrate-deficient transferrin is not affected by serum separators

We studied the possible effects on serum carbohydrate-deficient transferrin (CDT) determination by a CDTect (Pharmacia) method of serum isolation in four different types of blood-collection tubes, namely: (1) glass tubes (glass Vacutainer tubes with no additive); (2) S-Monovette Neutral tubes (plastic tubes with no additive); (3) S-Monovette Serum tubes (plastic tubes with kaolin-coated plastic granulate coagulation accelerator); and (4) S-Monovette Serum/Gel tubes (plastic tubes with kaolin-coated plastic granulate and a polymerized acrylamide resin). Using Passing and Bablok regression analysis, we did not observe significant differences in CDT concentrations determined in 58 serum samples using any of these four blood-collection systems.