| Iodine | Inorganic compounds | Homogeneous non-metal compounds | Homogeneous halogens | Not Available | Details |
| Isovalerylglycine | Organic compounds | Organic acids and derivatives | Carboxylic acids and derivatives | Amino acids, peptides, and analogues | Details |
| Indoxyl sulfate | Organic compounds | Organic acids and derivatives | Organic sulfuric acids and derivatives | Arylsulfates | Details |
| L-Kynurenine | Organic compounds | Organic oxygen compounds | Organooxygen compounds | Carbonyl compounds | Details |
| L-Leucine | Organic compounds | Organic acids and derivatives | Carboxylic acids and derivatives | Amino acids, peptides, and analogues | Details |
| Isovalerylcarnitine | Organic compounds | Lipids and lipid-like molecules | Fatty Acyls | Fatty acid esters | Details |
| Malonic acid | Organic compounds | Organic acids and derivatives | Carboxylic acids and derivatives | Dicarboxylic acids and derivatives | Details |
| Fe2+ | Inorganic compounds | Homogeneous metal compounds | Homogeneous transition metal compounds | Not Available | Details |
| L-2-Hydroxyglutaric acid | Organic compounds | Organic acids and derivatives | Hydroxy acids and derivatives | Short-chain hydroxy acids and derivatives | Details |
| Ketoleucine | Organic compounds | Organic acids and derivatives | Keto acids and derivatives | Short-chain keto acids and derivatives | Details |
| L-Methionine | Organic compounds | Organic acids and derivatives | Carboxylic acids and derivatives | Amino acids, peptides, and analogues | Details |
| 1-Methylnicotinamide | Organic compounds | Organoheterocyclic compounds | Pyridines and derivatives | Pyridinecarboxylic acids and derivatives | Details |
| Hydroxypropionic acid | Organic compounds | Organic acids and derivatives | Hydroxy acids and derivatives | Beta hydroxy acids and derivatives | Details |
| 4-Hydroxyphenylpyruvic acid | Organic compounds | Benzenoids | Benzene and substituted derivatives | Phenylpyruvic acid derivatives | Details |
| Glycoursodeoxycholic acid | Organic compounds | Lipids and lipid-like molecules | Steroids and steroid derivatives | Bile acids, alcohols and derivatives | Details |
| 4-Hydroxybutyric acid | Organic compounds | Lipids and lipid-like molecules | Fatty Acyls | Fatty acids and conjugates | Details |
| Hippuric acid | Organic compounds | Benzenoids | Benzene and substituted derivatives | Benzoic acids and derivatives | Details |
| Isovaleric acid | Organic compounds | Lipids and lipid-like molecules | Fatty Acyls | Fatty acids and conjugates | Details |
| L-Homoserine | Organic compounds | Organic acids and derivatives | Carboxylic acids and derivatives | Amino acids, peptides, and analogues | Details |
| 4-Hydroxyproline | Organic compounds | Organic acids and derivatives | Carboxylic acids and derivatives | Amino acids, peptides, and analogues | Details |
| Alpha-Hydroxyisobutyric acid | Organic compounds | Organic acids and derivatives | Hydroxy acids and derivatives | Alpha hydroxy acids and derivatives | Details |
| Hydroxykynurenine | Organic compounds | Organic oxygen compounds | Organooxygen compounds | Carbonyl compounds | Details |
| Indoleacrylic acid | Organic compounds | Organoheterocyclic compounds | Indoles and derivatives | Indoles | Details |
| Hydroxyphenylacetylglycine | Organic compounds | Organic acids and derivatives | Carboxylic acids and derivatives | Amino acids, peptides, and analogues | Details |
| Indole | Organic compounds | Organoheterocyclic compounds | Indoles and derivatives | Indoles | Details |
| Homocysteine | Organic compounds | Organic acids and derivatives | Carboxylic acids and derivatives | Amino acids, peptides, and analogues | Details |
| Malic acid | Organic compounds | Organic acids and derivatives | Hydroxy acids and derivatives | Beta hydroxy acids and derivatives | Details |
| 3-Hydroxyisovaleric acid | Organic compounds | Lipids and lipid-like molecules | Fatty Acyls | Fatty acids and conjugates | Details |
| Hydroxyphenyllactic acid | Organic compounds | Phenylpropanoids and polyketides | Phenylpropanoic acids | Not Available | Details |
| Glycogen | Organic compounds | Organic oxygen compounds | Organooxygen compounds | Carbohydrates and carbohydrate conjugates | Details |