Evaluation of kisspeptin levels in obese pregnancy as a biomarker for pre-eclampsia.

Objectives: Circulating concentrations of the peptide kisspeptin have been proposed as a novel biomarker for early detection of pre-eclampsia. Our aims were to assess analytical and clinical performance characteristics of a commercial kisspeptin assay and to determine sensitivity and specificity of the test for pre-eclampsia.

Design: Prospective, longitudinal study in a United Kingdom tertiary referral Antenatal Metabolic Clinic.

Patients: Severely obese (body mass index, BMI > 40 kg/m(2), n = 194) and lean (BMI < 25 kg/m(2), n = 78) pregnant women.

Measurements: A commercial kisspeptin ELISA (Phoenix Pharmaceuticals) was assessed for analytical sensitivity, specificity, precision, linearity, recovery and stability in maternal plasma samples at 16, 28 and 36 weeks gestation. Pre-eclampsia, defined using International Society for the Study of Hypertension in Pregnancy guidelines; blood pressure; delivery gestation; birthweight.

Results: Kisspeptin concentrations were lower in early pregnancy in obese women (P < 0.001), and in women who later developed pre-eclampsia (P < 0.05), compared with women with uncomplicated pregnancies. For 16-week plasma kisspeptin in prediction of pre-eclampsia, area under the receiver-operator characteristic curve was 0.80 (P < 0.01), positive and negative likelihood ratios were 3.0 and 0.2, and test sensitivity and specificity were 85.7 and 71.4%, respectively. In regression analyses, kisspeptin (16 weeks) associated positively with delivery gestation (P < 0.05) and birthweight (P < 0.0001), and negatively with 28- and 36-week blood pressure (P < 0.0001).

Conclusions: Kisspeptin concentration in early pregnancy is a promising biomarker for pre-eclampsia and low birthweight but cannot be recommended, in isolation, for universal screening because of inadequate test sensitivity and specificity. Large-scale studies are required to assess its potential in a panel of biomarkers.