SAT-480 Myxedema Madness: A Rare Case of Severe Hypothyroidism Presenting as Psychosis

Myxedema coma is a rare, life-threatening medical emergency resulting from uncontrolled hypothyroidism. Myxedema coma refers to the neurological sequelae of severe hypothyroidism, which classically manifests as depressed mental status. Rarely, myxedema coma can present with a hyperactive mental state and psychosis. We present an unusual case of a drug overdose secondary to myxedema coma-induced psychosis. Clinical Case A 48 year old woman with a history of seizure disorder and hypothyroidism presented to the hospital after lamotrigine overdose. The patient’s spouse witnessed her ingest forty-five tablets of lamotrigine after an argument. The patient had no previous psychiatric diagnoses or suicide attempts. On examination, the patient was hemodynamically stable but was agitated, disoriented, and uncooperative. She had a normal neurologic exam and no peripheral edema. Her lamotrigine level was 25.4 ug/ml (2.5-15.0 ug/ml). The patient’s mental status did not improve with lamotrigine cessation. Psychiatry determined that the patient’s psychosis was not consistent with lamotrigine overdose. Given these recommendations, alternative causes of psychosis were considered. The patient’s husband stated she had not taken levothyroxine for over one year. Thyroid function tests revealed a thyroid stimulating hormone (TSH) of 299 mcIU/ml (0.35-5.50 mcIU/ml) with a free thyroxine (T4) level of 0.27 ng/dl (0.89-1.76 ng/gl). The patient was started on levothyroxine intravenously. After five doses of intravenous levothyroxine, her mental status improved to baseline and she was transitioned to oral levothyroxine. She denied that the lamotrigine ingestion was a suicide attempt. Based on the patient’s presentation and clinical course, we concluded that her overdose was due to severe hypothyroidism leading to myxedema madness. Conclusion Severe hypothyroidism with myxedema coma often presents with depressed mental status, which can manifest as progressive confusion, lethargy, and eventually coma. However, in the case of our patient, severe hypothyroidism presented as psychosis, a rare manifestation. Remarkably, the patient had no other obvious physical manifestations of severe hypothyroidism. Psychosis, though rare, has been seen in cases typically after thyroidectomy or in patients with previously undiagnosed Hashimoto’s thyroiditis. In this patient’s case, it is likely that her myxedema madness was precipitated by long-term nonadherence with her thyroid replacement therapy, as the patient had no prior psychiatric history. Additionally, her rapid reversal of symptoms after the administration of levothyroxine supports the diagnosis of hypothyroid-induced myxedema madness.