<prompt> Which of the following is associated AV block?HypothyroidismHyperthyroidismPheochromocytomaCushing syndrome  <response>: Ans. a. HypothyroidismRef: Harrisons Principle of Internal Medicine 19th Ed; Page No-1471ETIOLOGY OF AV BLOCKAutonomic Carotid sinus hypersensitivityVasovagalMetabolicEndocrine HyperkalemiaHypermagnesemiaHypothyroidism Adrenal insufficiencyDrug-related Beta blockersCalcium channel blockersDigitalisAdenosineAntiarrhythmics class 1 and III LithiumInfectious Endocarditis Lyme disease Chagas disease SyphilisTuberculosisDiphtheriaToxoplasmosisInflammatorySLERheumatoid arthritis InfiltrativeAmyloidosisSarcoidosisMCTDSclerodermaHemochromatosisNeoplasticTraumaticLymphomaMesotheliomaMelanomaDegenerativeLevs diseaseRadiation Catheter ablationLenegres diseaseCoronary artery diseaseAcute Ml Abbreviations: MCTD, mixed connective tissue disease; Ml myocardial infarction; OMIM, Online mendelian Inheritance in Man database; designations: , phenotypic description, molecular basis known; phenotypic description; SLE, systemic lupus erythematosus 