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Table 6 Management of symptomatic hyperammonemia in undiagnosed patients and known patients with MMA/PA

From: Proposed guidelines for the diagnosis and management of methylmalonic and propionic acidemia

Ammonia level (μmol/l) Action in undiagnosed patient Action in known MMA/PA patient Comments
Increased > upper limit of normal Stop protein intake Stop protein intake Stop protein for maximal 24 (-48) hours
Give iv glucose at appropriate dosage (see Table 7) to stop catabolism ± insulin# Give iv glucose at appropriate dosage (see Table 7) to stop catabolism ± insulin
Avoid exchange transfusions as cause of catabolism/protein load
Monitor ammonia blood levels every 3 hours Increase carnitine dosage to 200 mg/kg/d
Hyperglycemia can be extremely dangerous (hyperosmolarity)
Monitor ammonia blood levels every 3 hours
100-250* As above As above
Start drug treatment with i.v. arginine, sodium benzoate and sodium phenylbutyrate (see Table 7) Start drug treatment with sodium benzoate (see Table 7)
If major hyperglycemia occurs with increasing lactate reduce glucose infusion rather than increasing insulin
Start carbamylglutamate, carnitine, vitamin B12 (preferably hydroxo-Cbl), and biotin (see Table 7) Consider carbamylglutamate (see Table 7)
Avoid hypotonic solutions
250-500 As above As above Add sodium and potassium according to the electrolyte results (cave hypokalemia when acidosis is corrected)
Prepare extracorporeal detoxification if significant encephalopathy and/or early high blood ammonia level or very early onset of disease (day 1 or 2) Consider extracorporeal detoxification dependent on patient's age and history
Take into account the sodium intake if sodium benzoate or phenylbutyrate is used
Begin extracorporeal detoxification if no rapid drop of ammonia within 3-6 hours
Avoid repetitive drug boluses
500-1000 As above As above Monitor phosphate levels and supplement early esp. during hemodialysis
Start extracorporeal detoxification immediately
>1000 Evaluate whether to continue specific treatment or to start palliative care As above
  1. *This limit of action applies for patients outside the neonatal period; for neonates use >150 and <250.
  2. #Monitor blood glucose after 30 min and subsequently every hour, because some neonates are very sensitive to insulin.
  3. 1 g sodium benzoate and sodium phenyl butyrate contain 7 mmol Na and 5.4 mmol Na, respectively.
  4. Grade of recommendation: C-D.