Lactate. The measurement of this is fundamental. It forms part of the sepsis six. It can also act as a tool to help predict mortality. Essentially, the crux of this is, the higher the lactate, the greater the mortality. However, more important than that it can help class how severe someone’s sepsis is but it can also reveal a cryptic septic shock in a patient who is apparently unwell, normotensive and not tachycardic. [RCEM 2015, Dellinger et al 2013, NCEPOD 2015] At the end of the day, you cannot go far wrong if you follow the sepsis six care bundle. So ultimately this initially boils down to giving three things and taking three things. Give oxygen, give broad spectrum antibiotics and fluids. Take blood cultures, measure lactate and monitor urine output. [Dellinger 2013] Footnote I need not reiterate the haste with which sepsis needs to be recognised and managed. Mortality equates to more than forty percent. You are seven times more likely to die as a result of sepsis than you are of an acute coronary syndrome. We have improved a lot of sepsis care, however as NCEPOD shows, we still have a way to go. [Leach 2014, NCEPOD 2015, RCEM 2015] Sepsis is a condition where you can make a palpable difference and a meaningful intervention within a very short space of time.