The evaluation of inflammatory markers in umbilical cord blood

We have read with great interest the article by Lausten-Thomsen et al. entitled "Inflammatory Markers in Umbilical Cord Blood from Small-For-Gestational-Age Newborns" in which they report Interleukin 6 (IL-6), Tumor necrosis factor-α (TNF-α) and C-reactive protein (CRP) levels in umbilical cord blood from small-for-gestational-age (SGA) and healthy newborns. In this regard, we would like to make some additions to paper in respect to interpretations of biochemical markers. Normal CRP concentration in healthy human serum is usually lower than 10 mg/L, slightly increasing with aging. Acute inflammatory response causes release of IL-6 and other cytokines that trigger the synthesis of CRP by the liver. In this article, IL-6 levels reported as elevated but CRP levels have remained in normal range. In this situation, increasing in IL-6 levels should be approached suspiciously. Although decreased TNF-α level was compatible with IL-6 levels, increased IL-6 levels did not cause CRP elevation in this study.