Is an anion gap of 14 (ref range: 0-12) worth following up on? the only other abnormality was low vitamin b12 (141 pg/ml). blood work was done due to mood changes (anxiety)?

If you feel physically well and healthy dont do anything except lead a normal life with good diet, exercise and anxiety by keeping busy, meditation, music, sports, social work etc.

Would not worry about the anion gap, but would certainly address the B-12 deficiency. Suggest initiating with injections, followed by oral or sublingual supplementation.