Table I.

Examples of Uremic Solutes and their Molecular Weights, Classified into 3 Groups: Small Water-soluble Compounds, Middle Molecules and Protein-bound Solutes (28, 33)

Molecule	Molecular weight	Example
Small water-soluble compounds	<500 Da	asymmetric dimethylarginine, guanidine, uric acid, oxalate, ethylamine, methylguanidine, neopterin, phenylacetic acid
Middle molecules	>500 Da	β2-microglobulin, adiponectin,α1-acid glycoprotein, cystatin C, prolactin, osteocalcin, vascular endothelial growth factor
Protein-bound solutes	Variable	p-cresylsulfate, indoxyl sulfate, phenol, indol-3-acetic acid, hippuric acid, homocysteine, carboxymethyllysine, acrolein