The cardiorenal syndrome is not well understood, and a uniform definition is lacking. Worsening renal function as determined by a decline in creatinine clearance in patients with decompensated heart failure is an identifier of patients with this syndrome. Treatment is a challenge. Diuretic therapy is valuable in treating congestion but may worsen renal function. Patients with decompensated heart failure are often refractory to diuretics, in which case higher doses must be used or alternate methods explored to reduce salt and water.