The most common reason of acquired hypothyroidism is autoimmune (Hashimoto) thyroiditis. Autoimmune thyroiditis can be atrophic or goitrogenic. Atrophic autoimmune thyroiditis (ATT) related acquired hypothyroidism causes interruption of growth, obesity, and bone age retardation in early ages while goitrogenic thyroiditis has a higher incidence rate and mostly presents with diffuse goiter. We discuss the effects of hypothyroidism on various systems through a case found to have pericardial effusion during the echocardiography performed after cardiac murmur was detected and later diagnosed with ATT related hypothyroidism.