Background The non-invasive assessment of volume status in left ventricular systolic dysfunction (LVSD) is challenging. The main thesis objective was to establish the feasibility and potential clinical utility of repeated measures assessment of non-invasive biomarkers in defining changes in volume status within individual volunteers. Methods Differential volume manipulation protocols were achieved in a three-staged plan of investigation[…] Results Summary I demonstrated the smallest variance for bioimpedance measures, and the largest variance for urine biomarkers […] Conclusion The repeated measures of biomarkers studied in response to different volume manipulations were interpreted in the context of their within-subject normal variance. None of the biomarkers studied appeared to have the ideal characteristics clinically for the monitoring of subclinical changes in volume status in stable LVSD or in response to acute diuresis in decompensated heart failure. The significant increases in urine biomarkers following diuretic withdrawal in stable LVSD suggested potentially beneficial renal effects of furosemide in stable LVSD.