Table 4 Levels of hyperammonemia and suggested actions in symptomatic patients Grade of recommendation, C-D
From: Suggested guidelines for the diagnosis and management of urea cycle disorders
Ammonia level (μmol/L) | Action in undiagnosed patient | Action in known UCD patient | Comments |
|---|---|---|---|
Above upper limit of normal | â–ª Stop protein intake | â–ª Stop protein intake | â–ª Stop protein for 24 h (maximum 48 h) |
|  | ▪ Give IV glucose at an appropriate dosage to prevent catabolism (10mg/kg/min in a neonate) ± insulina | ▪ Give IV glucose at an appropriate dosage to prevent catabolism (10mg/kg/min in a neonate) ± insulina | ▪ Avoid exchange transfusions as they cause catabolism |
| Â | â–ª Monitor blood ammonia levels every 3 h | â–ª Monitor blood ammonia levels every 3 h | â–ª Hyperglycemia can be extremely dangerous (hyperosmolarity) |
In addition | Â | Â | Â |
if >100 and <250 (in neonates, >150 and <250) | ▪ Start drug treatment with IV L-arginine and nitrogen scavengers (see Table5) | ▪ Continue drug treatment with L-arginine (plus continue or add L-citrulline for NAGSD, CPS1D or OTCD) and sodium benzoate ± sodium phenylbutyrate/ phenylacetateb (see Table5), increase dose or give IV | ▪ If major hyperglycemia occurs with high lactate (>3mmol/L) reduce glucose infusion rate rather than increase insulin |
| Â | â–ª Start carbamylglutamate, carnitine, vitamin B12, biotin (see Table5 and its legend) | â–ª Consider nasogastric carbohydrate and lipid emulsions unless the child is vomiting (enables higher energy intake) | â–ª Avoid hypotonic solutions |
In addition | Â | Â | Â |
if 250 to 500 | â–ª As above | â–ª As above, but all drugs per IV | â–ª Add sodium and potassium according to the electrolyte results |
| Â | â–ª Prepare hemo(dia)filtration if significant encephalopathy and/or early high blood ammonia level or very early onset of disease (day 1 or 2) | â–ª Prepare hemo(dia)filtration if significant encephalopathy and/or early high blood ammonia level or very early onset of disease (day 1 or 2) | â–ª Take into account the sodium intake if sodium benzoate or sodium PBA are used c |
|  | ▪ Begin hemo(dia)filtration if no rapid drop of ammonia within 3–6 h | ▪ Begin hemo(dia)filtration if no rapid drop of ammonia within 3–6 h | ▪ L-arginine not to be given in ARG1D |
In addition | Â | Â | Â |
if 500 to 1000 | â–ª As above | â–ª As above | â–ª Some concerns of sodium benzoate use in organic acidemias |
| Â | â–ª Start hemo(dia)filtration immediately | â–ª Start hemo(dia)filtration as fast as possible | â–ª Avoid repetitive drug boluses |
In addition | Â | Â | Â |
if >1000 | â–ª Evaluate whether to continue specific treatment or to start palliative care | â–ª Evaluate whether to aim at curative treatment or at palliative care | â–ª Monitor phosphate levels and supplement early specially with hemodialysis |