Dynamics of serum C-type natriuretic peptide as predictor for preeclampsia.

OBJECTIVE: To evaluate serum levels of the amino-terminal propeptide of C-type natriuretic peptide (NTproCNP) in uneventful pregnancies and pregnancies complicated by preeclampsia (PE) and NTproCNP's accuracy for prediction of PE.

STUDY DESIGN: Nested case control pilot study including women with uneventful pregnancy (Control, n = 100) and asymptomatic women who later developed PE (PE_long, n = 12). NTproCNP levels were measured in a maximum of ten sequential blood samples per patient (seven visits during pregnancy, three afterwards), which had been collected prospectively.

RESULTS: In controls, NTproCNP decreased from weeks 11-13 on, reaching a nadir at the end of the second trimester (weeks 23-27), and subsequently reached the highest levels at the end of pregnancy. In comparison, the PE_long group showed a significantly different NTproCNP course (p = .042), including significantly elevated levels in weeks 18-22 (p = .034) and 23-27 (p = .016). Significant predictive power of single time point measurements of NTproCNP for predicting short-term occurrence of preeclampsia in asymptomatic women was found in weeks 28-32 (p = .023) and 33-36 (p = .014). Furthermore, an increase > -0.038 pmol/l per week between weeks 11-13 and 14-17 was also predictive for PE (area under the curve, AUC: 0.75; p < .001; sensitivity: 90%; specificity: 60%), as was an increase of > 0.084 pmol/l per week between weeks 11-13 and 18-22 (AUC: 0.69, p = .048; sensitivity: 55%; specificity: 88%).

CONCLUSIONS: Measurement of NTproCNP in pregnancy might be useful to increase diagnostic awareness in women who will develop PE.