A system and method of detecting decompensation of heart failure for a patient includes urinalysis to determine the change in physical and/or chemical composition of a patient's urine over time. The change in chemical and/or physical composition of the patient's urine is used to infer the onset of decompensation. Optionally, the inference is verified with other data, such as with baseline transthoracic impedance data, patient weight data, and/or blood composition data.