What is Myxedema

Myxedema also known as Myxoedema is the characteristic reaction to thyroid hormone deficiency in the adult. it may result form radioiodine therapy, surgical excision, or primary atrophy or the thyroid or may develop secondary to hypofunction of the anterior pituitary or the hypothalamus.

Myxedema Symptoms and Signs

There is a gradual change in patients personality, coupled with the characteristic myxedematous facies, large tongue, slow and deep toned speech, thickened edomatous skin, puffiness of the hands and face, especially about the eyelids, drowsiness. In several cases, depressive psychosis or dementia may be stimulated. In prepuberal cases, menarche may be delayed, after puberty, menorrhagia is a frequent symptom. Deafness is observed occasionally. Cardiac enlargement and abnormal heart sounds may represent pericardial myxedema. The deep tendon reflexes oftern have a slow relaxation phase. The laggard achilles tendon reflex may be helpful in diagnosis.

Myxedema Diagnosis

The puffy facies is sometimes mistaken for the facial edema of acute nephritis Menorrhagia and anemia may lead to a false diagnosis of uterine tumor. serum T4, T3 resin uptak and thyroidal radioactive iodine uptake are low, while serum TSH is elevated. Serum cholesterol, carotene and total protein in blood and CSF are often elevated.

Myxedema Treatment

Recovery following administration of thyroid hormon is usually excelent, but therapy must be continued for life. In older patients with heart disease, the level of any thyroid hormon should be increased very slowly. In panhypopituitarism, Thyroid hormone therapy should be started after adrenocortical replacement therapy has begun.

What Causes Myxedema

Exophthalmos in particular results from TSH receptor stimulation on fibroblasts behind the eyes which leads to increased glycosaminoglycan deposition. It is thought that many cells responsible for forming connective tissue react to increases in TSH levels.
Secondarily, in autoimmune thyroid diseases lymphocytes react to the TSH receptor. Thus, in addition to the inflammation within the thyroid, any cell that expresses the TSH receptor will likely experience lymphocytic infiltrates as well. The inflammation can cause tissue damage and scar tissue formation, explaining the deposition of glycosaminoglycans.

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.


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