Lactate and lactic acid are not the same. They should be considered as opposite. It is typical for total lactate, acid and base lumped together and considered useful parameter.
When we consider the term oversimplification and the problem it creates, this is a good example. Considering total lactate as an independent value or parameter makes it easy but also obscures the important nature of acid base balance.
Rising total Lactate, acid and base together is considered an independent predictor of the state of metabolism. It is not appropriate to contrive an indicator of disease with two opposites combined together. Simplistically we do not need to consider the ratio of acid to base, only the total. This is a fallacy. Those who think for themselves and understand acid base chemistry consider that lactic acid and lactate base are not the same are maligned as, “not with the guidelines”. There will always be a ratio of lactic acid to lactate as a base. The more lactic acid predominates acid the worse the situation is. The total lactate should always be considered with the pH which determines the ratio of lactate to lactic acid. The more lactate pared with an inert cation such as sodium there is the more pH will go up and the more lactic acid there is the more the pH will go down. The important characteristic is how they affect hydrogen ion concentration, that is pH, each in the opposite direction.