preferred_name: Analysis of 11 endogenous agents (methylmalonic acid, xanthurenic acid, homocysteine, pyroglutamic acid, vanilmandelate, 5-hydroxyindoleacetic acid, hydroxymethylglutarate, ethylmalonate, 3-hydroxypropyl mercapturic acid [3-HPMA], quinolinic acid, kynurenic acid), by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in urine, algorithm reported as pain-index score with likelihood of atypical biochemical function associated with pain