Lactic acid is the normal byproduct of a normal physiological process designed to obtain energy for the body. Ordinarily, lactic acid is then sent to the liver where it is broken down to glucose, a form of sugar. During times of stress or low oxygen, the lactic acid isn’t effectively processed and begins building up in the blood. This can cause changes in the acid/base balance in the body and is an emergent condition.
Why is this relevant for women with PCOS? Some early studies and many clinicians believe that taking metformin, a drug commonly prescribed for women who have PCOS and insulin resistance, can slightly increase their chances for developing lactic acidosis, especially in women with impaired kidney function. More recent studies, however, have shown that this correlation may not actually exist.
Nevertheless, women taking metformin are usually advised to have a blood test to check their kidney function before starting and periodically throughout treatment. They should also watch out for signs of lactic acidosis, which include muscle weakness, nausea and fatigue, and report them promptly to their physician.
Salpeter SR, Greyber E, Pasternak GA, Salpeter EE. Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus. Cochrane Database of Systematic Reviews 2010, Issue 4. Art. No.: CD002967. DOI: 10.1002/14651858.CD002967.pub4