Abstract Details

Title Acquired Urea Cycle Disorder From Zinc Deficiency Causing Hyperammonemic Encephalopathy and Refractory Status Epilepticus

Topic Neuro Trauma and Critical Care

Presentation(s) P8 - Poster Session 8 (11:45 AM-12:45 PM)

Poster/Presentation
Number 18-005

Objective Describe relevance of zinc deficiency regarding urea cycle disorders (UCDs) in adults.

Background Urea cycle disorders are rare in adults but can be acquired by metabolic stressors or micronutrient deficiencies. Zinc is a necessary cofactor for ornithine transcarbamylase (OTC), a key step. Zinc deficiency may precipitate acquired defects leading to hyperammonemia and neurological sequelae.

Design/Methods N/A

Results A 54-year-old female with gastric bypass, small bowel resection, and recurrent vomiting for years presented to the emergency department for subacute imbalance and acute confusion. On day two of admission, she became somnolent and increasingly altered, prompting neurology consultation. On initial examination, she was awake with a gaze preference but produced no speech, followed no commands, and withdrew symmetrically. CT/CTA Head/Neck, MRI Brain with/without contrast and CSF studies were unrevealing. Initial EEG showed 1-2Hz triphasic discharges. On day six, she began having left-central-onset seizures, then generalized status epilepticus refractory to IV lorazepam 12mg, levetiracetam, fosphenytoin, and lacosamide, requiring multiple infusions. She was empirically repleted with 100mg IV B6, a cofactor for GABA synthesis. Subsequent studies revealed ammonia of 384 umol/L (82 umol/L on admission; ref. 16-53umol/L), significant deficiencies in zinc (25.1ug/dL, ref. 60-120ug/dL) and B6 (6.2nmol/L, ref. 20-125nmol/L). Glutamine was elevated. She was repleted with oral zinc and continued B6. Hyperammonemia was emergently managed with hemodialysis. On day eight, sedatives were weaned without return of seizures; she was arousable and tracking. Repeat MRI showed cortical diffusion restriction, edema and T2 hyperintensities consistent with hyperammonemia. Invitae hyperammonemia panel was negative, and a final diagnosis of acquired urea cycle disorder precipitated by zinc deficiency was rendered.

Conclusions Zinc deficiency can cause acquired OTC deficiency, precipitating hyperammonemia. Prompt recognition and evaluation are essential to prevent injury, as in this case, without other explanation for her profound clinical picture. Concurrent B6 deficiency, impairing GABA synthesis, likely also contributed to seizure risk.

Authors/Disclosures
Jenna L. Miller, MD PRESENTER	Dr. Miller has nothing to disclose.
Joy Suh, MD	Dr. Suh has nothing to disclose.
Aaron M. Carlson, MD (University of Colorado, School of Medicine, Department of Neurology)	Dr. Carlson has received research support from Horizon Therapeutics (Amgen).
Daniel Pastula, MD, MHS, FAAN (University of Colorado, Department of Neurology)	Dr. Pastula has nothing to disclose.
Peter Hountras, MD	The institution of Dr. Hountras has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for United Therapeutics. The institution of Dr. Hountras has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Merck. The institution of Dr. Hountras has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Johnson and Johnson. The institution of Dr. Hountras has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Gossamerbio. The institution of Dr. Hountras has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Inari. The institution of Dr. Hountras has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Imperative Care. The institution of Dr. Hountras has received research support from Inari. The institution of Dr. Hountras has received research support from Department of Defense. The institution of Dr. Hountras has received research support from HRSA. The institution of Dr. Hountras has received research support from NIH.

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