Paediatric age-dependent serum transferrin isoform distribution studied by HPLC.

Background: Human serum transferrin shows different transferrin isoforms with e.g. a varying amount of glycosylation, resulting in asialo-, mono-, di-, up to octasialotransferrin. We wanted to examine whether there are age-dependent differences in this transferrin isoform distribution.

Methods: Serum samples from a total of 126 paediatric patients (mean/median/minimum/maximum: 6.8/6.0/0.5/14 years) grouped in seven age groups (<2 years, 3-4 years, up to 13-14 years) were analyzed on an HPLC (Recipe Chemicals & Instruments GmbH, Munich, Germany). Means, medians and percentiles were computed for each transferrin isoform and tested for statistically significant differences between the age groups.

Results: CDT corresponded to disialotransferrin (since asialo- and monosialotransferrins were not detectable) and did not show statistically significant differences between the 7 age groups. The latter is also true for trisialo- and tetrasialotransferrin whereas pentasialotransferrin shows a statistically significant decrease with age.

Conclusions: We suggest that age-independent decision limits, e.g. the 95% percentiles for disialotransferrin (1.1%) and trisialotransferrin (5.3%), can be used for the differentiation between normal and increased fractions of these isoforms until paediatric reference ranges have been established. The presence of asialo- and monosialotransferrin in paediatric serum should be considered as abnormal.