Serum activin A and inhibin A. New clinical markers for hydatidiform mole

Although human placenta is a well established, rich source of proteins, hCG is the only measurement available to date in diagnosing the occurrence of the hydatidiform mole. Serum levels of a new placental protein, immunoreactive inhibin, were high in molar pregnancy, but the inhibin assay never became of clinical use, due to its low specificity and reliability. Since specific assays are now available for inhibin A, inhibin B, and activin A, the current study evaluated whether and which of these placental proteins is increased in presence of a molar pregnancy.

Serum inhibin A, inhibin B, activin A, and hCG levels were assayed in: A) 6 women with molar pregnancies, before and after evacuation; B) 37 healthy pregnant women; and C) 22 healthy nonpregnant women.

Women with partial hydatidiform moles had significantly higher serum levels of inhibin A (P < 0.001) and activin A (P < 0.001) than healthy pregnant women, several fold higher than the 95% confidence interval of control values. After evacuation, the levels of both inhibin A (P < 0.001) and activin A (P < 0.05) declined significantly to the levels of nonpregnant controls. Molar hCG concentrations were significantly higher than in normal pregnancy (P < 0.001), but some values within the 95% confidence interval of normal values. Despite a significant decrease (P < 0.05) after evacuation, hCG levels were still higher than in nonpregnant women.

The present data strongly suggest that serum inhibin A and activin A measurement may be of value in diagnosis and short-term follow-up of molar pregnancy.