This discordance suggests the need to study underlying factors in these patients, such as variations in inflammatory response, variability in mesothelial response, genetic variability in genes regulating CA-125 synthesis or release, differences in the activation of the autonomic nervous system and the renin–angiotensin–aldosterone system, other comorbidities and/or medications, and, of course, the clinical presentation of HF [40]. Here, REN is linked to hydrops fetalis.