Decreases lipoic acid serum levels of vitamin B-12?

Tetra-hydrolipoic acid is a metabolite of lipoic acid which may cause vitam in B-12 hypovitaminosis by formation of chelates. It was demonstrated in a 45-year old healthy subject that abnormally low serum levels of vitamin B-1 2 may result from long-term treatment with lipoic acid. Therefore serum con centrations of vitamin B-12 should be measured in patients with polyneuropa thy before and at four to six-week intervals after the initiation of medica tion with lipoic acid.