Concurrence of clozapine-induced diabetic ketoacidosis and neuroleptic malignant syndrome: A case report.

RATIONALE

Clozapine is a unique antipsychotic drug used to treat treatment-resistant psychosis. Clozapine can induce metabolic complications and weight gain, and may lead to acute diabetic complications such as diabetic ketoacidosis (DKA). Neurological side effects of clozapine are relatively rare compared with those of typical antipsychotics; however, several cases have been reported. In particular, reports have suggested that clozapine-induced neuroleptic malignant syndrome (NMS) may present with atypical features. While multiple reports document DKA and NMS occurring separately in patients receiving clozapine, no cases have been reported in which they occur simultaneously. We report a case in which DKA and NMS developed concurrently, with NMS manifesting atypical features and the significant stress associated with NMS hindering recovery from DKA.

PATIENT CONCERNS

A 23-year-old man presented to the emergency department with generalized weakness and shortness of breath. He had been diagnosed with schizophrenia 3 years earlier and was taking medications prescribed at another hospital. His regimen was changed 2 months prior to presentation.

DIAGNOSIS

Arterial blood gas analysis revealed high anion gap metabolic acidosis and elevated blood ketone levels. The patient was diagnosed with DKA, and intensive insulin therapy was initiated. However, he developed fever and altered mental status during treatment, and despite intensive insulin therapy, the improvement of metabolic acidosis was hindered. Although the typical symptoms of NMS, such as rigidity and a rapid increase in creatine kinase (CK), were not observed, based on the history of clozapine treatment, persistent fever, altered mental status, and blood pressure instability, NMS was diagnosed.

INTERVENTIONS

Insulin and intravenous fluid therapy were continued for DKA, and clozapine was discontinued.

OUTCOMES

Following clozapine discontinuation, metabolic acidosis, fever, and altered mental status improved rapidly.

LESSONS

DKA and NMS share various signs, such as fever, altered mental status, blood pressure instability, dyspnea, and tachycardia. Therefore, in patients receiving clozapine, the simultaneous occurrence of DKA and NMS should be considered. Additionally, clozapine-induced NMS may present in an atypical form; therefore, even in the absence of typical signs, such as rigidity and a rapid increase in CK, the possibility of NMS should be reconsidered.