Inhibin-A and superimposed preeclampsia in women with chronic hypertension

OBJECTIVE: To determine if maternal serum inhibin-A can be used as a marker for subsequent development of superimposed preeclampsia in women with chronic hypertension. METHODS: Serum for measurement of inhibin-A was obtained at monthly intervals in women with chronic hypertension requiring antihypertensive medications. Superimposed preeclampsia, the primary outcome of interest, was diagnosed when hypertensive women developed proteinuria (at least 300 mg per 24-hour urine specimen). Serum inhibin-A was considered abnormally elevated when the value exceeded the mean plus two standard deviations of the log for chronically hypertensive women who did not develop preeclampsia. RESULTS: A total of 61 women were enrolled in this study, and 21 (34%) developed superimposed preeclampsia. Inhibin-A levels increased with advancing gestational age. Ten women had abnormally increased inhibin-A levels; eight (80%) developed superimposed preeclampsia, compared with 13 of 51 (26%) women with normal inhibin-A levels (P <.001). Sensitivity and specificity were 38% and 95%, respectively, whereas the positive and negative predictive values were 80% and 75%, respectively. CONCLUSION: Although inhibin-A was abnormally increased an average of 3 weeks before the clinical onset of superimposed preeclampsia, the sensitivity of the test as a screen was too limited to be clinically useful.