NPPB and pericardial effusion: Diagnostic and monitoring markers for hypothyroidism-related cardiac effects include standard thyroid function tests (TSH, FT4, FT3); electrocardiography to detect bradycardia or conduction abnormalities; echocardiography to evaluate pericardial effusion and ventricular function; advanced echocardiography, such as speckle-tracking, for subtle myocardial dysfunction; and biomarkers of cardiac stress, including troponin and NT-proBNP.