Saturday, May 22, 2010

TOPIC DISCUSSION: Hyperammonemia and the Nephrologist

Why and when does a nephrologist get called for hyperammonemia? Yes its true, dialysis can be a modality to treat severe high toxic levels of ammonia.

1. Why is it so dangerous?
Cerebral edema and herniation (as well as seizures) are unique to acute hyperammonemia and usually occur only when arterial ammonia levels are > 200 μmol/L.  Chronic brain damage has been noted.

2. What are the treatment choices?
  Treat the intracranial hypertension created and treatment of cerebral edema.
  Hypothermia can help, along with mannitol
  Diltantin and Phenobarbital
  Treat underlying urea splitting organism if present
  Sodium Benzoate
  IV arginine
  PD/HD and CVVH have been used in the past!! and in most cases as a bridge to liver transplantation.

 3. What are the causes?
     Liver  failure/cirrhosis
     TPN,GI Bleed, Steroid use
     Urea splitting organism infection, herpes infection
     Urinary diversion
     Multiple Myeloma  
     Budd chiari
     Valproic Acid, carbamazepine, ribavarin, pyrimethamine use
     Urea cycle disorders( usually children)
     idiopathic hyperammonemia
Few interesting points.  
This can be very devastating and we might get called to do dialysis as a final removal of the ammonia. HD removes it the fastest. A nice review is listed below.
Another interesting cause that I learned was Multiple Myeloma and how that might lead to the elevated hyperammonemia syndrome needing dialysis. This might be associated with presence of peripheral blood myeloma cells and a possible MM with a burkitt type translocation t(2,8)(p12;q24)

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