Wednesday, August 25, 2010

Hepathic Encephalopathy

Hepathic encephalopathy(HE) is a syndrome characterized by impaired mentation,neuromuscular disturbances and altered consciousness.There are multiple causes which can cause HE.HE actually is one of the cirrhosis complication.

HE can be caused by ammonia.When the liver fails,it is unable to detoxify ammonia thus it is a direct cerebral toxin.CSF test for ammonia metabolytes which are glutamine and alpha ketoglutarate are being measured to determine the severity of HE.

The main source of ammonia is its endogenous production by the gastrointestinal tract from the metabolism of protein and from the degragdation of bacteria and blood from GI bleeding.

Osmotic laxative(lactulose,neomycin) helps to remove ammonia and reduce colonic ammonia production.

Another theory of pathogenesis of HE is Branch-chained amino acids(BCAAs) vs Aromatic amino acids(AAAs)

A plasma amino acid imbalance exist in ESLD in which the BCAAs decreased and AAAs increased.

The BCAAs furnish as much as 30% of energy requirement for skeletal muscle,heart and brain when gluconeogenesis and ketogenesis are depressed.This cause serum BCAAs levels to fall.

At the same time,plasma AAAs and methionine are released into circulation by muscle proteolysis,but the synthesis into protein and liver clearance of AAAs is depressed.This changes the plasma molar ratio of BCAAs to AAAs and may contribute to the development of HE;AAAs may limit the cerebral uptake of BCAAs brcause they compete for carrier-mediated transport at the blood-brain barrier

p/s:belajar dari kesilapan,please be alert~