CST3 and hydrops fetalis: Additionally, concentrations of troponin, the interleukin receptor family member soluble (s)ST2 [9-11], renal measures such as cystatin C (cys-C) [12], and inflammatory markers such as myeloperoxidase (MPO) [13,14] have all been linked to adverse risk in HF, presumably as they reflect these various deleterious processes in such patients.