Table 2.
Summary of protocol of acute management of hyperammonemia
| • Basic life support (CAB) |
| • Stop all source of protein both enteral and parenteral nutrition for a maximum of 24–48 hours |
| • Check glucose level (GlucoCheck) |
| • Insert an IV line (central and peripheral) and take blood for ammonia (NH3), blood gases, Chem 1, and CBC, blood C/S (peripheral and central if patient has central line). Liver transaminases, Ca, alkaline phosphatase as STAT order |
| • Ammonia should be taken with precaution (without tourniquet, transported in ice water to the laboratory, separated within 30 minutes of collection, and analyzed immediately) |
| • Start 1.5 to double maintenance IVF as D10%, 0.45 NS + KCl 30 meq/L until serum K result is available, then adjust accordingly |
| • Call the pharmacy to prepare the medications and intralipid (see dosages in Tables 1 and 4) |
| • Call biochemical geneticist (metabolic) on call |
| • Consider starting insulin if hyperglycemia develops (glucose >10 mmol/L) at dose of 0.05–0.1 unit/kg/h and titrate up until blood glucose controlled (keep GlucoCheck 6.5–10 mmol/L). Total glucose requirements (mg/kg/min) depends on the age (0–1 year: 8–10, 1–3 years: 7–8, 4–6 years: 6–7, 7–12 years: 5–6, adolescent: 4–5, adults: 3–4) |
| • If ammonia >100 μmol/L in infants, children, and adults; and >150 μmol/L in neonates start loading dose of combined sodium benzoate and sodium phenylacetate (AMMONUL®) and arginine (see Tables 1 and 4) |
| • Start IV intralipid 20% 2–3 g/kg/day to give additional calories (if fatty acid oxidation defects are excluded) |
| • If the patient is on combined sodium benzoate and phenylacetate (AMMONUL®) or arginine give KCl 40 meq/L because they cause hyperchloremic hypokalemic metabolic acidosis. KCl can be given through peripheral line up to 60 meq/L; rate must not exceed 0.125 meq/kg/h |
| • Start dialysis if ammonia >300–500 μmol/L in neonates and children and there is no response to the medical treatment within 4 hours. Consult ICU and nephrology team if you anticipate starting dialysis in the next few hours |
| • Reloading has to be done carefully, in particular during the first 24 hours, as cumulative doses of >750 mg/kg/24 h of combined sodium benzoate and phenylacetate (AMMONUL) have been shown to be associated with development of toxicity (vomiting, lethargy). Reloading only in neonates with severe disorders or those who are undergoing dialysis, and should be spaced at least 6 hours |
| • In an undiagnosed acute case also start N-carbamylglutamate (Carbaglu®). It only exists as an enteral form, so it is generally given by NG tube. Give 100 mg/kg once followed by 50 mg/kg q 6 h. Once it is clear that the patient does not have NAGS or CPS1 deficiency or organic acidemias, it should be stopped |
| • In an undiagnosed acute case, start levocarnitine IV/PO 100 mg/kg/day divided q 6–8 h, hydroxycobalamin 1 mg IM/IV/PO, and biotin 10 mg IV/PO |
| • Give glucose polymers, or protein-free formulas (eg, Pro-phree, Polycose, or Maxijul) through PO/NG as tolerated to give additional calories |
| • Do not decrease dextrose rate or amount and do not stop calorie delivery in the acute stage for any reason (eg, medications, fluid bolus, or hyperglycemia) as this can precipitate hypoglycemia and catabolism, which will further worsen the patient’s condition |
| • Call metabolic dietitian on call |
| • If patient has a known diagnosis, do not stop other oral chronic medications (in case of vomiting, convert to IV forms if available) |
| • Antibiotics may be started if there is any evidence of sepsis. Ammonia, electrolyte, and blood gases analysis need to be done at regular intervals during this acceleration of management stage. The frequency is dictated by the patient’s condition and the speed at which results can be obtained |
| • Protein should be reintroduced within 24–48 hours of initiation of therapy even if the patient is on dialysis |
Abbreviations: CBC, complete blood count; CAB, circulation, airway, breathing; Chem 1, Na, K, Cl, creatinine; C/S, culture and sensitivity; Ca, calcium; NAGS, N-acetylglutamate synthase; CPS1, carbamoyl phosphate synthetase 1; IVF, intravenous fluid; D10, dextrose 10%; NS, normal saline; NG, nasogastric; h, hours; IM, intramuscular; IV, intravenous; PO, peroral.