localized (pretibial) myxedema
• | found in 1-4% of patients with Grave’s disease, especially those with exophthalmos |
• | may not develop until after the correction of hyperthyroidism (e.g. after thyroidectomy) |
• | treatment of hyperthyroid does not improve lesion and, often, pretibial myxedema develops after it |
• | pathogenesis: a circulating factor which stimulates increases synthesis of glycosaminoglycans (but not LATS – long acting thyroid stimulator) |
generalized myxedema
• | manifestation of severe hypothyroidism |
• | does not occur in secondary hypothyroidism (i.e. low TSH) |
• | most pronounced around eyes, nose, and cheeks, often giving characteristic facies |
• | suggested that pathogenesis is impaired degradation |
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