The importance of determining plasma CoQ10 levels during CoQ10 supplementation cannot be overemphasized. Minimum target plasma level must be established for any given condition for therapeutic efficacy. For instance, in the case of in heart patients, we now know that a minimum of 3 mcg per mL plasma must be reached before any clinical benefit can be expected.

Duration of CoQ10 supplementation is another important consideration. In many of the early trials with CoQ10, blood levels were rarely monitored. It is quite likely that in those situations where a beneficial effect was not observed, it may be due to the fact that the blood levels did not reach the therapeutic range.

In healthy adults, normal values for CoQ10 are 0.8 to 1.5 micrograms per milliliter.