Correction of hyperthyroidism was also associated with a decrease in FGF21 from 58 (55-64) to 52 (47-58) pg/mL ( P < 0.001) and in leptin levels from 17 (7-36) to 11 (4.6-28) ng/mL ( P = 0.03). Here, LEP is linked to hyperthyroidism.