Introduction:

Ammonia is a resultant molecule from the protein metabolism that can be neurotoxic when present in high concentrations, causing brain edema and encephalopathy. Extracorporeal blood purification technique (EBPT) can play a role in reducing both ammonia and urea blood levels. However, there are no specific guidelines for its use in hyperammonemia, due to its low incidence and scarce literature on this subject, particularly in adults.

Case report:

The authors describe a case of a 22‑year‑old previously healthy woman. She presented with polyuria, polydipsia, anorexia, vomiting and significant (>10%) weight loss over a month. Laboratory data revealed hypoglycemia and a high anion gap metabolic acidosis with severe acidemia with normal lactate, serum creatinine of 1.12 mg/dl and 260 (reference value 26‑74)umol/l of ammonia. Urine analysis showed ketone bodies. She evolved with progressive encephalopathy and neurological deterioration. The hypothesis of hyperammonemic encephalopathy secondary to a hereditary metabolic disease was suspected. Medical supportive therapy was initiated.

An EBPT for ammonia removal and acid‑base correction was initiated using continuous venovenous hemodiafiltration (CVVHDF) with a drastic neurologic improvement. A fatty acid beta‑oxidation deficit was discovered. The patient was discharged with no neurological changes, with a strict diet free of fat, animal protein and high‑protein

vegetables, plus supplementation with benzoate, carnitine, riboflavin, maltodextrine and essential amino acids.

Discussion and conclusion:

In adults, hyperammonemia related to metabolic disorders is rare, and in the presence of encephalopathy, ECDT should be considered. Ammonia is easily dialysable either by intermittent or continuous techniques. CVVHDF provides a continuous clearance with less rebound effect.

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