Follicular fluid and serum levels of inhibin A and pregnancy-associated plasma protein A in patients undergoing IVF.

Objective: To elucidate transport of intrafollicular proteins Inhibin A and pregnancy-associated plasma protein A (PAPP-A) across the follicular fluid (FF)/blood barrier.

Design: A retrospective study.

Setting: IVF lab at a university hospital, academic, and industrial research labs.

Patient(s): Fifty-five women undertook the IVF program.

Intervention(s): Follicular fluid aspirations and analysis, blood sample drawing, and serum analysis.

Main Outcome Measure(s): Concentrations of Inhibin A, PAPP-A, and major serum proteins in FF and serum, total amount of PAPP-A, and Inhibin A in FF.

Result(s): The FF/blood barrier permeability was calibrated using major serum proteins. The FF/serum ratio decreased with the molecular mass of proteins, and their FF and serum concentrations were well correlated. In contrast, concentrations of Inhibin A in paired serum and FF samples showed a weak correlation (r = 0.563), whereas serum and FF concentrations of PAPP-A were independent of each other. The total amount of Inhibin A in FF correlated well with concentrations of Inhibin A in paired serum samples (r = 0.858), whereas the correlation between the total amount of FF PAPP-A and PAPP-A serum concentrations remains poor (r = 0.215).

Conclusion(s): These observations suggest that at the day of oocyte retrieval, FF is a major source of serum Inhibin A but not of serum PAPP-A.