Major clinical weight loss (often accompanied by a ravenous appetite), intolerance to heat, fatigue, weakness, hyperactivity, irritability, apathy, depression, polyuria, polydipsia, and sweating. Additionally, patients may present with a variety of symptoms such as palpitations and arrhythmias (notably atrial flutter or atrial fibrillation), shortness of breath (dyspnea), loss of libido, nausea, vomiting, and diarrhea. In the elderly, these classical symptoms may not be present and they may present only with fatigue and weight loss leading to apathetic hyperthyroidism.

Neurological manifestations are tremor, chorea, myopathy, and periodic paralysis. Stroke of cardioembolic origin due to coexisting atrial fibrillation may be mentioned as one of the most serious complications of hyperthyroidism.

As to other autoimmune disorders related with thyrotoxicosis, an association between thyroid disease and myasthenia gravis has been well recognized. The thyroid disease, in this condition, is often an autoimmune one and approximately 5% of patients with myasthenia gravis also have hyperthyroidism. Myasthenia gravis rarely improves after thyroid treatment and the relationship between the two entities is as yet unknown. Some very rare neurological manifestations that are reported to be dubiously associated with thyrotoxicosis are pseudotumor cerebri, amyotrophic lateral sclerosis and a Guillain-Barré-like syndrome.

Exophthalmos or (protrusion of the eyeball) occurs in Graves’ disease, but it is not caused by the hyperthyroid state in that disease, and is unrelated to it. Exophthalmos, when present, may exacerbate ocular signs, however.^[1]