pretibial myxedema

Rarely, people develop a skin condition known as pretibial myxedema.

Pretibial myxedema seen in Graves' disease is also known as Osler's sign.

Pretibial myxedema (lumpy, reddish skin of the lower legs)

Neurological seizures, neuropathy from nerve entrapment by lesions of pretibial myxedema, and hypokalemic periodic paralysis may occur.

The two signs that are truly 'diagnostic' of Graves' disease (i.e., not seen in other hyperthyroid conditions) are exophthalmos and non-pitting edema (pretibial myxedema).

Other known triggers for ophthalmopathy include thyroid hormone imbalance, and tobacco smoking, but there has been little research attempting to confirm these are also risk factors for pretibial myxedema.

Pretibial myxedema (myxoedema (UK), aka thyroid dermopathy ) is an infiltrative dermopathy, resulting as a rare complication of Graves' disease, with an incidence rate of about 1-5% in patients.

Major clinical signs include weight loss (often accompanied by an increased appetite), anxiety, intolerance to heat, hair loss, muscle aches, weakness, fatigue, hyperactivity, irritability, hypoglycemia, apathy, polyuria, polydipsia, delirium, tremor, pretibial myxedema, and sweating.

Virtually all the symptoms and signs of Graves' disease result from the direct and indirect effects of hyperthyroidism, with exceptions being Graves' ophthalmopathy, goitre and pretibial myxedema (which are caused by the autoimmune processes of Graves' disease).

There are suggestions in the medical literature that treatment with Radioactive Iodine for Graves' hyperthyroidism may be a trigger for pretibial myxedema which would be consistent with radioiodine ablation causing or aggravating Ophthalmopathy, a condition which commonly occurs with pretibial myxedema and is believed to have common underlying features.