Misdiagnosed Postpartum Psychosis Revealing a Late-Onset Urea Cycle Disorder

Abstract

pected. on readmission to the obstetric ward, her treatment included risperidone (2 mg/day), alprazolam (1.5 mg/day), the phenothiazine antipsychotic cyamemazine (62.5 mg/day), and the anticholinergic tropatepine (10 mg/day). Antibiotic treatment was started to treat a possible infection. Unlike in her previous postpartum episodes, Mrs. G’s mental status responded only partially to antipsychotic treatment. A liaison psychiatry consultation was requested. the liaison psychiatrist found a mildly agitated and disoriented young woman who had wet herself and was circling around her bed. the patient was logorrheic, and her speech, which was mostly incoherent, revealed memory impairment. Strikingly, this mild state of confusion fluctuated during the interview, confirming midwives’ reports of hourly changes in the patient’s behavior. Mrs. G anxiously expressed feelings of guilt toward her newborn and the belief that her diagnosis of postpartum psychosis made her less able to take care of her children. She displayed no anger toward her children and no ideas of persecution, infanticide, or suicide. She also expressed the belief that “God talks to humankind through premonitory dreams or providential meetings,” a claim that had previously been interpreted as a mystic delusion. However, it appeared that this view was part of her cultural and religious background, as was later confirmed by her husband, who reported that she had held this belief for a long time and that it was shared by her relatives. overall, Mrs. G was more confused and less delusional than one would have expected in a typical postpartum psychosis. Puzzled by this clinical picture, the psychiatrist reconsidered the diagnosis of postpartum psychosis and extended his examination to assess the differential diagnosis. He found that Mrs. G had chronic headaches and a habitual reluctance to consume meat. His clinical examination revealed little; the patient had a well-tolerated fever, stable blood pressure and pulse, and no signs of severe sepsis. A neurological examination was unremarkable. the psychiatrist ordered immediate blood tests, including ammonia levels. Within an hour, hyperammonemia was confirmed (224 μmol/liter, controls <50 μmol/liter), along with a respiratory alkalosis and a marked inflammatory syndrome. Results of liver function tests, as well as all the other blood tests, were normal. the psychiatrist contacted the internal medicine fellow, who confirmed the need for an immediate multidisciplinary management of a probable late-onset urea cycle disorder. He decided to transfer the patient to the intensive care unit (ICU), despite the reluctance of the obstetrical team, who felt that the patient should instead be in a secure psychiatric facility. In the ICU, an etiologic treatment of urea cycle disorderinduced hyperammonemia was immediately started unMisdiagnosed Postpartum Psychosis Revealing a late-onset Urea Cycle Disorder