Current laboratory monitoring may not be optimal.A retrospective chart review was performed on thelaboratory results of 246 patients who were treatedwith isotretinoin for acne over a 9-year period. Testsobtained were CBC, lipid panel, AST, ALT, CK, GGT,and C-reactive protein. Thirty-five patients had anelevated AST and 35 of these had an elevated CK; 32had an elevated ALT and 11 of these had an elevatedCK. Thirteen patients had an elevated GGT; in 5 thiswas the only abnormality, whereas 8 had a GGTelevation accompanied by an elevated AST or ALT.Two had an elevated GGT and an elevated CK withnormal AST and ALT. Fifty-two patients had a singleepisode of elevated CK, of which 22 were female.However, 57 had multiple CK elevations and only onewas female. Thirty-five patients had CK elevations <2 times normal; 38 had levels between 2 and 3 timesnormal, 18 had levels between 3 and 4 times normal,and 18 had levels greater than 4 times normal. Wesuggest that ALT and AST are not useful for monitoringisotretinoin therapy and that GGT and CK may be ofgreater value in managing patients.