Inclusion Criteria:

• 1. A clinical diagnosis of ADHF with at least one objective sign of volume overload (rales, edema, elevated JVP, or preadmission weight gain)
• 2. As judged by the treating physician, a projected need and ability to tolerate treatment with an extended need for IV diuretics with the goal of significant fluid removal (i.e., goal \>1L/day net fluid loss)
• 3. Chronic daily oral loop diuretic dose \> or equal to 20mg furosemide equivalents for at least one month prior to admission
• 4. eGFR 30 mL/min/1.73 m2
• 5. Signed informed consent

Exclusion Criteria:

• 1. Current use or plan to initiate renal replacement therapy or ultrafiltration this hospital admission
• 2. Significant bladder dysfunction or urinary incontinence
• 3. Inability to comply with the serial urine collection procedures
• 4. Current use of a thiazide or thiazide like diuretics or use within 5 half-lives of the drug, including metolazone
• 5. Prior heart transplant, critical stenotic valvular disease or complex congenital heart
• 6. History of type 1 diabetes, diabetic ketoacidosis, "brittle" diabetes or frequent hypoglycemia or severe hypoglycemic episodes requiring emergent intervention (ER visit or EMS response, glucagon administration or forced oral carbs) in the last 3 months
• 7. History of or current urosepsis or frequent urinary tract infections
• 8. Anemia with hemoglobin \<8g/dL (due to required phlebotomy for the study)
• 9. Pregnancy or breastfeeding