BACKGROUND: Recent studies showing an improved diagnosis of iron deficiency (ID) with soluble transferrin receptor (sTfR) and sTfR-ferritin index did not take into account the age-dependency of sTfR and ferritin. Moreover, there is a paucity of data on pediatric reference intervals for sTfR and sTfR-ferritin index.

METHODS: A study cohort of 436 apparently healthy children was analyzed to establish reference intervals for ferritin, transferrin, sTfR and sTfR-ferritin index. To account for age-dependency, standard deviation scores (Z-scores) for these markers were calculated. The association between these parameters and C-reactive protein (CRP) was analyzed.

RESULTS: The Z-scores of ferritin, transferrin and sTfR had a significant association with CRP, whereas the Z-score of sTfR-ferritin did not correlate with CRP. The reference intervals of these parameters were reported.

CONCLUSION: Among the different markers of ID, the Z-scores of sTfR, transferrin and ferritin, but not sTfR-ferritin index, associate with the inflammatory status.