Thyroid hormones, including total T3, total T4, free T3, free T4 and inverse T3, are now described as the diseases that cause them to increase. T4emia; sixth, medications, including amiodarone, iodine-containing contrast agents, estrogens, birth control pills, fenadine and thyroxine tablets, can increase T4; seventh, altitude sickness can have transient total T4 elevation. Common diseases with elevated serum free T3 and free T4 include: first, primary hyperthyroidism; second, thyroid hormone resistance syndrome; third, thyroiditis; and fourth, drugs, such as heparin and amiodarone can cause elevated free T4. Common diseases with elevated anti-T3 include: first, primary hyperthyroidism; second, non-thyroidal diseases, such as acute myocardial infarction, cirrhosis, diabetes, uremia, cerebrovascular accident, tumors of the gastrointestinal tract, acidosis, heart failure, endocarditis, and other infectious diseases, can elevate anti-T3; and third, certain drugs can elevate anti-T3.