Every student learns the mnemonic “MUDPILES” for the diagnosis of anion gap metabolic acidosis (AGMA), but I think the one on that list that is the most misunderstood is lactic acidosis. In and of itself, “lactic acidosis” is more of a problem than a diagnosis. I’ve never yet had a patient who had spontaneous hyperlactatemia, yet we often want to just says that the patient has “lactic acidosis” and leave it at that.
When approaching the patient with an AGMA, if there is an elevated lactate, we can’t just jump to the conclusion that “lactic acidosis” is the cause, and even if it is, we need to dig in to determine WHY the lactate is elevated. and it turns out, that’s a complex question. There are a number of things than can cause an elevated serum lactate, it’s not just tissue ischemia, and despite the idea of “trending lactates” in sepsis, elevated lactate doesn’t always = sepsis.
Obiajulu Anozie (@icuexplained) has a great post over on Instagram that goes over the basics of classifying and further diagnosing a lactic acidosis. Once the cause has been identified, then you can get to work treating the cause, rather than just bolusing IVF until the “lactate clears.”