NPPB and cardiac hypertrophy: To confirm the hyperthyroid status and cardiac hypertrophy of model rats, serum free T3 and T4 concentrations, hemodynamic parameters heart rate(HR), systolic blood pressure (SBP), and left ventricular systolic pressure (LVSP), and serum levels of the cardiac hypertrophy markers NT-proBNP and FGF-23 were measured (Fig. 1A–J) after the final day of treatment.