Adrenomedullin (ADM), a 52 amino acid peptide, is a member of the calcitonin peptide family and is widely expressed in many tissues and organs. It has been shown to have a variety of physiological functions, including immune-modulating, direct bactericidal, diuretic and potent vasodilatory activity. In healthy subjects, ADM circulates at low picomolar concentrations. In many pathological states such as hypertension, renal failure, lower respiratory diseases and septic shock, plasma levels of adrenomedulin are significantly up-regulated in proportion to disease severity. These unique properties makes it a potentially useful marker in determination of the patients most at risk of developing complications on admission to the ED, in order to rapidly triage and administer the most effective treatment in the shortest possible time.