<unk>  or para-aminohippuric<unk>  (PAH), a derivative of hippuric<unk> , is a diagnostic agent useful in medical tests involving the kidney used in the measurement of renal plasma flow.  It is an amide derivative of the amino<unk>  glycine and para-aminobenzoic<unk>  that is not naturally found in humans; it needs to be IV infused before use diagnostically.
Aminohippuric acid
Aminohippurate
Pyruvic acid
Cyanic acid
Choline
Alpha-ketoglutaric acid
Cysteamine 
Stearic acid