Soluble Transferrin Receptor during infancy and reference intervals for the Roche Cobas platform

INTRODUCTION: Infant iron status assessments may be difficult to interpret due to infections. The soluble transferrin receptor (sTfR) has been suggested as a biomarker mainly unaffected by the acute phase response. Reference intervals reflecting dynamics of infant growth first year in life are not well established. METHODS: The sTfR and CRP concentrations were measured in samples from 451 term infants with the Roche Cobas platform in umbilical cord, at 48‐96 hours, 4 and 12 months. Reference values were constructed as the 2.5th and 97.5th percentiles. The relationship between CRP concentrations >1 mg/L and sTfR was tested by Kendall correlation. RESULTS: Reference intervals for girls and boys were 2.4‐9.5 mg/L at birth, 2.9‐8.4 mg/L at 48‐96 hours, 2.6‐5.7 mg/L at 4 months and 3.0‐6.3 mg/L at 12 months. No differences between sexes were observed except for at 4 months. sTfR did not covariate with CRP concentrations >1 mg/L except in 48‐96 hours samples. CONCLUSION: This study reports reference intervals for sTfR from birth to 12 months of age in a large group of infants in a low‐risk area for iron deficiency. sTfR might add value to infant iron status diagnostics since no covariation with CRP was found at birth, at 4 months or at 12 months.