: Myxoedema) is a term used synonymously with severe hypothyroidism
. It is also to describe a dermatological
change that can occur in hypothyroidism, and some forms of hyperthyroidism. This article discusses the dermatological changes.
In this context, myxoedema refers to deposition in the dermis. This results in swelling of the affected area. One manifestation of myxoedema occurring in the lower limb is pretibial myxedema, a hallmark of Graves disease. Myxoedema can occur in Hashimoto's thyroiditis and other long-standing forms of hypothyroidism, as well as Graves disease, an autoimmune form of hyperthyroidism.
The word myxoedema originates from μύξα, taken from ancient Greek to convey 'mucus' or 'slimy substance' and ὁίδημα for swelling.
Signs and symptoms
Myxoedema can occur in the lower leg (pretibial myxedema
) and behind the eyes (exophthalmos
Myxoedema is known to occur in various forms of hypothyroidism
, and also in Graves' disease
. One of the hallmarks of Grave's disease is pretibial myxedema, myxoedema of the lower limb.
[ ξ1 ]
Myxoedema is more common in women than in men.
[ ξ2 ]
Myxedema can occur in:
Myxedema describes a specific form of cutaneous
and dermal edema
secondary to increased deposition of connective tissue
components. These can include
, hyaluronic acid
, and other
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The increased deposition of glycosaminoglycan is not fully understood, however two mechanisms predominate:
Fibroblast stimulation. It is thought that fibroblast stimulation by the thyroid stimulating hormone (TSH) receptor increases the deposition of glycosaminoglycan. This results in an osmotic edema and fluid retention. It is thought that many cells responsible for forming connective tissue react to increases in TSH levels.
Lymphocyte stimulation. In Basedow-Graves' thyroid disease, lymphocytes react against the TSH receptor. Lymphocytes react not only against thyroid receptors, but also any tissue with cells expressing the receptor. This can lead to tissue damage and scar tissue formation, explaining the deposition of glycosaminoglycans.
^ William D. James, Dirk M. Elston, Timothy G. Berger9781437703146
, Saunders/ Elsevier. ISBN 9781437703146
^ Arthur S. Schneider (2019
, Wolters Kluwer Health/Lippincott Williams & Wilkins. ISBN 9781451109061