Abstract
Background: Previous studies reported that C-reactive protein (CRP), an acute phase protein, is present in amniotic fluid (AF) and fetal urine. Elevated AF-CRP levels have been associated with adverse pregnancy outcome such as preterm delivery and neonatal infection. Although it is known that adult kidneys normally do not excrete CRP, it has not been investigated whether there is CRP urine excretion immediately after birth. Therefore, we have conducted a study to explore if early neonatal urine contains CRP.
Methods: Consecutive newborns admitted to the neonatal intensive care unit were included in the study. Urine samples were obtained in the first week of life using sterile cotton flock. After centrifugation of the flock, CRP was collected in sterile tubes and sent immediately to the laboratory. Urinary CRP was measured with a commercially available ELISA kit. The sensitivity of the assay was 0.39 ng/mL (Inter-assay coefficient of variation: 6.5%). The urinary CRP values were normalized for the urinary creatinin content of every single probe. Spearman correlation was used for statistical purposes.
Results: Urinary CRP was measured in 83 infants. Mean gestational age at delivery and birth weight was 33±4.3 weeks and 1907±945 grams, respectively. A total of 66 (78.6%) neonates were delivered preterm (<37 weeks gestation). Neonatal urine was collected at a median (range) day of life of 2 days (1–7). CRP was found in all samples. The median (range) concentration was 8.07 ng/ml (0.08–929) ng/ml. A significant correlation was found between urinary CRP concentration and both gestational age at delivery (r=−0.60, p<0.0001) and the days of life (r=−0.51, p<0.0001).
Conclusion: CRP is detectable in the neonatal urine at delivery and decreases during the early neonatal period. This could be explained by the progressive maturation of the neonatal kidneys. It remains to be explored whether urinary CRP measurements in neonates at high risk for an adverse outcome has a prognostic value.
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Tandoi, F., Agosti, M., Nelle, M. et al. 252 C-Reactive Protein in The Neonatal Urine at Birth. Pediatr Res 56, 506 (2004). https://doi.org/10.1203/00006450-200409000-00275
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DOI: https://doi.org/10.1203/00006450-200409000-00275
