Hyperthyroidism may lead to high anxiety status, emotional lability, irritability, overactivity, exaggerated sensitivity to noise, and fluctuating mood, insomnia and hyporexia. In extreme cases, they may appear delusions and hallucinations as psychiatric symptoms.

We report the case of a 53-year-old female who was diagnosed of hyperthyroidism and generalized anxiety disorder. The patient went to emergency department because of high levels of anxiety, with heart palpitations, trembling, shortness of breath and nausea. She was presenting auditory hallucinations and delusions as psychiatric symptoms. An urgent thyroid profile was made and it was observed the next results: TSH<0.005; T4:4; T3:21. Due to a severe thyroid malfunction, the patient was admitted and treated with antithyroid agent, improving the psychiatric and somatic symptoms.

In this case, a patient diagnosed of hyperthyroidism and generalized anxiety disorder presented very severe psychiatric symptoms, with hallucinations and delusions. These symptoms may be produced by primary psychiatric disorders, but is very important to look for thyroid alterations, because if they are the cause, the acute treatment of thyroid malfunction is the correct management of the patient.

Hyperthyroidism is very common in general population, being infradiagnosed most of times. In patient with anxiety or other psychiatric symptoms, it is very important to make a thyroid function tests before the diagnosis of a psychiatric disorder. In extreme cases, hyperthyroidism status may lead to severe psychiatric and somatic complications.