FGF21 and External ophthalmoplegia: Elevated serum levels of alanine, lactate, creatine kinase, and fibroblast growth factor 21, and abnormal urine organic acid profiles are other findings in CPEO.[1,5] Besides, CPEO in Kearns-Sayre syndrome is associated with pigmentary retinopathy and cardiac conduction abnormalities which typically present before the age of 20.[7]