Uncontrolled Hypothyroidism with Antiphospholipid Syndrome Resulting in Myxedema Psychosis

We describe a female patient with a history of antiphospholipid syndrome, hypothyroidism, and bipolar disorder, who presented with worsening mood and psychotic symptoms following discontinuation of medications. Laboratory evaluations revealed markedly elevated thyroid-stimulating hormone (TSH) of 190 mU/mL. She also had a remote history of intracranial hemorrhage and required long-term anticoagulation with warfarin. We posit that the psychosis and mood presentation were attributable to the interplay between hypothyroidism-induced neuropsychiatric symptoms, decompensation of bipolar disorder, and history of antiphospholipid-related ischemic cerebral injury. Myxedema psychosis was further supported as a diagnosis given her extremely elevated TSH, sudden symptom onset following discontinuation of levothyroxine and other medications, limited improvement with risperidone, and significant clinical improvement after restarting levothyroxine. The etiology of her hypothyroidism was considered to be autoimmune in nature, given its relationship with antiphospholipid syndrome. We emphasize the importance of recognizing autoimmune and endocrine causes of neuropsychiatric symptoms, particularly hypothyroidism, which has a prevalence as high as 18% depending on the population. Optimizing psychiatric medication doses may not be sufficient in these populations, and an accurate prognosis requires accounting for the impact of the untreated hypothyroidism and comorbid autoimmune condition. Our patient was unable to obtain maximum resolution of symptoms until we also treated her hypothyroidism.