Abstract
BACKGROUND: TGF-β superfamily members are important biomarkers of reproductive health in women desiring fertility and during pregnancy. TGF-β proteins derived from the ovary and/or placenta have been detected in serum in women, but there have been very few attempts to measure them non-invasively, such as in urinary samples, and to compare them to serum concentrations. METHODS: We measured inhibin A, inhibin B, total inhibin, AMH, activin A, activin B, activin AB, follistatin, the GDF-9/BMP-15 complex, and GDF-15 in paired serum and urine samples from healthy reproductive aged women and in pregnant (second trimester) women. RESULTS: We detected all hormones in serum in both pregnant and non-pregnant women. Inhibin A, total inhibin, activin A, activin AB, follistatin, and GDF-15 were significantly higher in pregnant than in non-pregnant women. GDF-15 was the only hormone consistently detected in urine. We also measured, for the first time, the GDF-9/BMP-15 functional heterodimer and the GDF-15 protein harboring the H202D polymorphism. CONCLUSIONS: We report the successful measurement of the GDF-9/BMP-15 heterodimer (its native form) in serum and the ability to measure GDF-15 non-invasively, in urinary samples. This novel GDF-15 assay also captures the antigen in the presence of a common genetic variant.