GDF15 and hydrops fetalis: Increased plasma concentrations of biomarkers such as TNF-alpha, ST2, IL-1, interleukin-6 (IL-6), interleukin-8 (IL-8), Gal-3 (Gal-3) or growth differentiation factor 15 (GDF15) are considered as characteristic for HF [2, 19, 21].