Table 2.

Colon-derived solutes excreted in human urine

Colon-Derived SoluteUrinary Excretion Rate Colectomy/ControlDetected in Control Patient Urine, %Detected in Colectomy Urine, %Previously Identified as Colon-DerivedPlasma Ultrafiltrate Hemodialysis/ControlUrinary Clearance Rate Relative to CreatinineFree Fraction, %
Identified as uremic
 Phenylacetylglutamate0.1810092319.2
 Cinnamoylglycine0.0810067x177.3
p-Cresol glucuronide0.001008x171.75.3±2.18±5
 Phenylacetylthreonine0.20948161.4
 Phenylacetylserine0.148217126.6
 Phenylacetylalanine0.1410025125.3
 4-Acetylphenol sulfate0.249450122.0
 Phenylacetylmethionine0.12820114.5
 6-Hydroxyindole sulfate0.081003383.418.8±7.21±0.6
 Phenylacetylhistidine0.111002582.5
 3-(3-Hydroxyphenyl) propanoic acid sulfate0.04100877.7
 Trimethylamine N-oxide0.14100100x59.81.7±0.637±7
 Indoxyl sulfate0.08100100x52.618.7±4.62±0.7
 Phenylacetylglutamine0.22100100x46.63.6±0.637±5
 2-Oxindole-3-acetate0.131005838.6
 3-Hydroxyhippuric acid0.0410067x30.613.2±8.625±8
p-Cresol sulfate0.01100100x27.47±1.22±0.4
 3-Methoxycatechol sulfate0.1910010025.44.9±1.38±2
 Thioproline0.25761722.70.6±0.53±1
 Indoleacetic acid0.1110010018.18.8±8.22±0.8
 2,8-Quinolinediol sulfate0.07882517.4
 4-Ethylphenylsulfate0.0110050x16.6
 Phenol sulfate0.23100100x16.62.4±0.47±2
 Vanillyl alcohol sulfate0.131008314.28.1±12.646±57
 2-Acetamidophenol sulfate0.041001712.5
 2-Aminophenol sulfate0.1210075x11.30.9±0.329±18
 4-Methylcatechol sulfate0.0410067x11.18.4±2.93±1
 Formylanthranilic acid0.20100428.1
 Azelaic acid0.22100676.31.7±1.960±33
 Pyrocatechol sulfate0.23100925.13.2±0.99±2
 Gentisic acid0.10100674.8
 1,2,3-Benzenetriol sulfatea0.17100924.0
 5-Hydroxyhexanoaic acid0.126582.50.7±0.364±49
Not identified as uremic
 CMPF0.195982.6
 3-(3-Hydroxyphenyl) propanoic acid0.225902.11.4±0.911±3
 5-Androstenediol disulfate0.1594501.5
 Picolinic acid0.1688251.30.7±0.325±7
 N-Methyltaurine0.078801.3
 Fructose0.2082420.80.03±0.02110±49
 1,2,3-Benzenetriol sulfateb0.118858
 3-Hydroxyphenylacetatic acid0.1110033
 Indolepropionylglycine0.041008
 N-Acetylhistamine0.1810075
 Piperidine0.07100100
 Pregnen-diol disulfate0.2110075
 Triethanolamine0.1410092
  • Values are mean±SD unless otherwise stated. Urinary clearance rate relative to creatinine and free fraction are reported if both values could be calculated for at least eight out of 17 control patients. Clearance rates and free fractions are calculated from peak areas measured in different sample matrices and provide only estimates of the extent of secretion and protein binding. Solutes were classified as uremic if the ratio of average plasma ultrafiltrate hemodialysis to average control peak areas was >2.4 with the difference in average peak areas q<0.05. Compound names are those used by the Human Metabolomic Database (47), except for CMPF, which is 3-carboxy-4-methyl-5-propyl-2-furanpropanoate.

  • a Sulfate group on second carbon in 1,2,3-benzenetriol sulfate.

  • b Sulfate group on first carbon in 1,2,3-benzenetriol sulfate.