ABSTRACT
Maple syrup urine disease (MSUD) is an inborn error of metabolism caused by a defect in the branched-chain alpha-ketoacid dehydrogenase complex (BCKDC). This leads to the accumulation of the branched-chain amino acids (BCAAs) leucine, isoleucine, and valine, which can cause neurotoxicity. Patients with MSUD are carefully managed from birth with dietary restrictions and can acutely decompensate in the setting of infections or injury. We present the case of a 29-year-old female with a history of MSUD and rheumatoid arthritis on methotrexate and adalimumab who presented to our emergency department with symptoms suggestive of a metabolic crisis including nausea, vomiting, and presyncope. She was diagnosed with coronavirus disease 2019 (COVID-19) and admitted. An initial leucine level was mildly elevated at 253 µmol/L, consistent with her underlying metabolic condition. She was placed on an infusion of normal saline and 10% Dextrose (D10) in addition to a protein-restricted sick-day diet. Remdesivir therapy was initiated due to her immunocompromised status and high risk for decompensation but had to be discontinued due to nausea and vomiting that negatively impacted the patient's oral intake. Her leucine level peaked at 647 µmol/L; however, her neurologic examination remained benign without signs of cerebral edema. With prompt involvement of our metabolic genetics team and initiation of intravenous fluids and the sick-day diet protocol, we avoided a metabolic crisis. The patient was discharged on day 5 of hospitalization with no complications from COVID-19 infection. This case highlights the individualized approach to the treatment of COVID-19 infection in a patient with a metabolic disorder. COVID-19 infection in the setting of MSUD has only been reported in two prior publications, one being a severe metabolic crisis with neurologic involvement. Fortunately, our patient experienced a mild case of COVID-19 without significant respiratory symptoms, and we were able to prevent a metabolic crisis during admission.