Detection and potential utility of C-reactive protein in saliva of neonates.

Objective: We aimed to detect C-reactive protein (CRP) in neonatal saliva and evaluate its diagnostic utility.
Study Design: Salivary and serum samples (n = 89) were collected from 40 neonates. Salivary CRP levels were determined using an enzyme-linked immunosorbent assay; serum CRP was measured per hospital protocol. Correlation coefficients with 95% confidence intervals and robust linear regression measured association while receiver-operator characteristic curves described the accuracy of salivary CRP in discriminating abnormal serum CRP thresholds of ≥10 and 5 mg/L. Corresponding sensitivities and specificities were calculated for these salivary cutpoints.
Results: The area under the curve for salivary CRP in predicting serum CRP levels of ≥10 and 5 mg/L were 0.81 and 0.76, respectively. The corresponding sensitivity and specificity for raw salivary CRP to discriminate a serum CRP of ≥5 mg/L was 0.54 and 0.95, respectively. The corresponding sensitivity and specificity for raw salivary CRP to discriminate a serum CRP of ≥10 mg/L was 0.64 and 0.94, respectively. A statistically significant correlation was observed between serum and salivary CRP (r = 0.62, p < 0.001).
Conclusion: C-reactive protein is detectable in neonatal saliva and can predict abnormal serum CRP thresholds. Salivary CRP analysis represents a feasible screening tool for detecting abnormal serum CRP levels.