BackgroundQuantitative methods have shown clinically significant heterogeneity in blood volume (BV) profiles in patients with chronic heart failure (HF). How patient sex might impact this volume heterogeneity and relationship to cardiac hemodynamics remains to be defined. MethodsRetrospective analysis of clinical and quantitative BV, plasma volume (PV) and red blood cell (RBC) mass data was undertaken across three medical centers. BV was quantitated using nuclear medicine I-131-labelled plasma albumin indicator-dilution methodology with cardiac hemodynamics obtained within 24 hours. ResultsIn an analysis of 149 males and 106 females absolute BV was greater on average in males (6.9±1.7 vs. 5.0±1.2 liters, p<0.001) however, a wide range in BVs was demonstrated in both sexes (2.9 to 14.5 liters). Male sex was associated with higher prevalence of large (>+25% of normal) BV and PV expansions (36% vs. 15% and 51% vs. 21%, respectively, both p<0.001). In contrast, female sex was associated with higher prevalence of normal total BV (44% vs. 27%, p=0.005), PV (54% vs. 27%, p<0.001), hypovolemia (23% vs. 11%, p=0.005) and true anemia (42% vs. 26%, p<0.001). Cardiac hemodynamics differed by sex but only modest associations were demonstrated between volume profiles and cardiac filling pressures. ConclusionsFindings support unique intravascular volume profiles reflecting sex-specific differences in the prevalence and distributions of total BV, PV and RBC mass profiles in chronic HF patients. This underscores the importance of recognizing patient sex as a significant factor influencing volume homeostasis which needs to be taken into account to effectively individualize volume management strategies.