Hyperthyroidism and thyrotoxicosis occur when the thyroid gland overproduces thyroid hormones. Thyroid storm is a life-threatening exacerbation of thyrotoxicosis caused by factors like infection, surgery, or medication changes. It involves fever, sweating, tachycardia, anxiety, and heart failure. Treatment focuses on cooling the patient, blocking further hormone production with antithyroid drugs and iodine, and supporting heart and brain function with beta-blockers and glucocorticoids. Thyroidectomy may be required for severe cases not responding to medical management.