Activin A and inhibin A as possible endocrine markers for pre-eclampsia

Inhibin A and activin A are produced by the placenta during human pregnancy. This study aimed to measure circulating concentrations of inhibin A, pro alpha C-containing inhibins, and activin A in the serum of women with pre-eclampsia and of healthy matched control pregnant women, and to establish the molecular-weight forms of circulating inhibin A and activin A in pre-eclampsia.

In a retrospective cross-sectional study, blood samples were taken from 20 women in hospital with established pre-eclampsia, and from 20 control pregnant women attending antenatal clinics, who were matched for duration of gestation (pre-eclampsia mean 29.15 [SD 3.75] weeks; controls 29.30 [3.93] weeks), parity, and maternal age. Serum samples were analysed for inhibin A, inhibin B, pro alpha C, and activin A. Pooled samples of control (n = 3) and pre-eclampsia serum (n = 3) subsequently underwent fast protein liquid chromatographic analysis to assess the molecular-weight forms of inhibin A and activin A. Results are expressed as mean and SD for all variables measured.

Serum concentrations of inhibin A, activin A, and pro alpha C were significantly higher in pre-eclampsia than in control normal pregnancy (inhibin A 3.05 [1.8] vs 0.36 [0.14] ng/mL, p < 0.001; activin A 38.08 [25.88] vs 3.95 [2.32] ng/mL, p < 0.001; pro alpha C-containing inhibins 2.2 [0.81] vs 0.71 [0.33] ng/mL, p < 0.001). Inhibin B concentrations in maternal serum were not increased. Molecular-weight forms of inhibin A (32 kDa) and activin A (> 100 kDa) were similar in pre-eclampsia and normal pregnancy. The mean concentrations of hCG were 59.05 [43.98] and 16.3 [8.72] ng/mL, respectively.

Higher maternal serum concentrations of inhibin A, pro alpha C, and total activin A in pre-eclampsia than in control pregnancies could be helpful in the diagnosis of pre-eclampsia. These changes are interpreted as further evidence for trophoblast dysfunction in pre-eclampsia.