Amino acid dysbalance in liver failure is favourably influenced by recirculating albumin dialysis (MARS).
BACKGROUND
Dysbalance between branched chain (BCAA) and aromatic amino acids (AAA), which can be quantified by a low Fischer's Index (SigmaBCAA/SigmaAAA), as well as elevated levels of free tryptophan in plasma are common in hepatic failure and may contribute to the development of hepatic encephalopathy.


OBJECTIVE
To evaluate the influence of a new extracorporeal detoxification system for liver failure (Molecular Adsorbents Recirculating System, MARS(R), i.e. dialysis against a recirculating albumin solution cleaned online by charcoal and an anion exchange resin) on plasma tryptophan and Fischer's Index.


METHODS
Plasma samples were taken before, during and after MARS treatments (n = 11, mean blood flow 135 ml/min, mean dialysate flow 120 ml/min, high flux polysulfone membrane). Simultaneous to blood sampling, aliquots of the albumin dialysate were taken between the elements of the dialysate circuit.


RESULTS
Fischer's Index in systemic blood increased during MARS by 24% (from 1.44 to 1.79, P < 0.001; mean treatment duration, 5.5 h). Systemic tryptophan level was significantly reduced at the same time (-25%, n = 8). Amino acid removal rates from plasma during a single dialyser passage ranged from 10 to 53%. In particular, AAA were preferentially removed (42-44% throughout treatment), while BCAA removal was 28-46% initially and later declined to 24-28%. A maximum concentration gradient between plasma and dialysate was maintained for the AAA throughout treatment through their apparently complete removal by the charcoal adsorber. Conversely, BCAA removal at both adsorbers was only minor. As a result, Fischer's Index showed a significant increase in the processed plasma, which became even more pronounced with increasing treatment duration.


CONCLUSIONS
MARS enables an elevation of a pathologically decreased Fischer's Index as well as a reduction of systemic tryptophan levels in patients with liver failure. The effects of MARS on plasma amino acid dysbalance may contribute to an improvement of hepatic encephalopathy.
Loock
J
J
Department of Nephrology, Clinic for Internal Medicine, University of Rostock, Germany.
Mitzner
S R
SR
Peters
E
E
Schmidt
R
R
Stange
J
J
D000596:Amino Acids / Q000097:blood*; D006501:Hepatic Encephalopathy / Q000097:blood / Q000628:therapy; D006801:Humans; D017114:Liver Failure, Acute / Q000097:blood / Q000628:therapy*; D006435:Renal Dialysis; D012709:Serum Albumin / Q000378:metabolism*; D016060:Sorption Detoxification; D014364:Tryptophan / Q000097:blood
D000596:Amino Acids; D012709:Serum Albumin; D014364:Tryptophan