REN and hydrops fetalis: ADM is a circulating peptide hormone synthesized by endothelial and vascular smooth muscle cells, the biologically active form of which has been proposed as a marker and inhibitor of tissue fluid congestion, a hallmark feature of HF.55 Consistent with our results, it has been hypothesized that ADM may play a protective role in HF development and progression by maintaining vascular integrity, inducing vasodilatation, and inhibiting the renin-angiotensin-aldosterone system.55