Secondary outcomes include serum PCS , total and free ( unbound ) concentrations ; cardiovascular risk , measured by serum lipopolysaccharides , serum trimethylamine-N-oxide ( TMAO ) and inflammation and oxidative stress markers ; kidney damage , measured by 24hour proteinuria and albuminuria , estimated glomerular filtration rate and renal tubule damage ( urinary kidney injury molecule-1 ) ; patients ' self assessed quality of life ; and gastrointestinal symptoms .