Myxedema describes a specific form of cutaneous and dermal edema secondary to increased deposition of connective tissue components (like glycosaminoglycans, hyaluronic acid, and other mucopolysaccharides) in subcutaneous tissue as seen in various forms of hypothyroidism and Graves' disease. It is more common in women than in men. The word originates from , taken from ancient Greek to convey 'mucus' or 'slimy substance' and for swelling. The increased deposition of glycosaminoglycan is not fully understood, however two mechanisms predominate. The increased deposition of glycosaminoglycans causes an osmotic edema and fluid collection. Hashimoto's thyroiditis is the most common cause of myxedema in the United States.