MON-449 - Delayed Neuropsychiatric Recovery in Severe Hypothyroidism: A Case of Myxedema Psychosis

Myxedema psychosis arises from severe hypothyroidism, prolonged hypothyroidism and can present with acute psychosis. Recognition may be delayed when neuropsychiatric symptoms do not parallel early biochemical improvement after thyroid hormone replacement. This case illustrates that delayed neuropsychiatric recovery can be seen in cases of severe hypothyroidism and myxedema psychosis even with standardized treatment.

A 44-year-old woman with lifelong hypothyroidism and no prior psychiatric history presented with 7 days of acute altered mental status accompanied by auditory and visual hallucinations. She had discontinued levothyroxine for approximately one year and was found to have laboratory findings consistent with severe untreated hypothyroidism, including a markedly elevated TSH with low thyroid hormone levels. Levothyroxine was re-initiated a week prior to presentation. On admission, thyroid function testing demonstrated partial improvement however her neuropsychiatric symptoms notably worsened. Although the thyroid hormone levels slowly improved with hormone replacement therapy during the course of the hospital admission, the neuropsychiatric symptoms persisted and the patient’s mental status showed delayed and inconsistent improvement. A comprehensive evaluation for alternative etiologies of acute psychosis and delirium, including infection, adrenal insufficiency, metabolic abnormalities, toxic exposure, and structural brain disease, was unremarkable. A short trial of antipsychotic medication was initiated and later discontinued without recurrence of primary psychiatric symptoms. The predominant cause of the psychiatric presentation still supported the initial diagnosis of myxedema psychosis.

This case highlights the importance of using a holistic but systematic approach in rare symptomatic presentations. Myxedema psychosis often occurs with mismanaged hypothyroidism and treatment consists of repleting thyroid hormones with appropriate standardized dosing. This patient's psychosis emerged while receiving adequate treatment for her severe hypothyroidism with improvement of thyroid values. In this scenario, hypothyroidism treatment was unable to manage new-onset psychosis which underscores the complexity of medical decision-making in patient care and demonstrates that standardized treatment may result in unexpected clinical outcomes.

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