Letter to the editor: “Undifferentiated non-hepatic hyperammonemia in the ICU: Diagnosis and management”

An Important, Potentially Life-Threatening Cause of Acute Adult Disorders of Consciousness Is Missing From the Evaluation Done by Chang et al

“…Although diffusive therapies may have some theoretical advantages, there is no clear evidence that any particular modality is superior. Peritoneal dialysis and exchange transfusion have both been DoC as inferior treatment strategies and the role of more complex blood purification methods is still unclear (2–4). Conventional hemodialysis can rapidly reduce ammonia concentrations.…”

“…The correlation between plasma ammonia and the severity of encephalopathy and cerebral edema is somewhat variable (5). Levels of more than 100 μmol/L are highly predictive of encephalopathy in hepatic hyperammonemia, while ammonia concentrations over 150 μmol/L in adults are associated with intracranial hypertension that may lead to neurologic injury and death from brainstem herniation (2–4).…”

“…Severe liver failure is a common cause of hyperammonemia in ICU patients and requires urgent treatment to avoid neurologic complications and even death (2). However, nonhepatic hyperammonemia in ICU patients can pose diagnostic and management challenges for clinicians (2)(3)(4). Nutritional and metabolic factors can also contribute to these complex disorders and need to be considered in management (2)(3)(4).…”

“…However, nonhepatic hyperammonemia in ICU patients can pose diagnostic and management challenges for clinicians (2)(3)(4). Nutritional and metabolic factors can also contribute to these complex disorders and need to be considered in management (2)(3)(4). Causes of nonhepatic hyperammonemia, such as drugs, infection, and inborn errors of metabolism may be unfamiliar to clinicians and may be overlooked.…”

Ammonia and nutritional therapy in the critically ill: when to worry, when to test and how to treat?

“…These bacteria hydrolyse urea, leading to increased production of ammonia. Alkalisation of the urine occurs with uropathogenic strains of these organisms, promoting increased concentrations of ammonia of up to 50% compared with neutral pH [13 ▪ ,14]. As an electrically neutral and lipid-soluble molecule, the increased urinary ammonia (NH 3 ) concentration leads to a gradient that results in the diffusion of ammonia into urothelial cells.…”