A method for diagnosing and monitoring pulmonary hypertension using free hemoglobin, as well as surrogates for free hemoglobin, as markers for pulmonary hypertension. Bodily fluids, such as blood, serum, plasma, urine and/or breathe condensate may be collected and analyzed to determine the concentration of free hemoglobin or surrogates of free hemoglobin. The concentration indicates the presence or absence of pulmonary hypertension
