Assays and methods for diagnosing substance use disorder

A method for diagnosing Substance Use Disorder (SUD), adapted for use with a urine sample, that comprises,

• analyzing the urine sample spectrophotometrically with a SUD Diagnostic Panel comprising:
• an Oxidant History assay that utilizes a phosphotungstate reagent to measure uric acid in the sample and compare the amount of uric acid to a pre-determined value, such that an amount of uric acid below the pre-determined value indicates the urine sample is invalid;
• a short-duration counterfeit urine assay that utilizes thymolphthalein monophosphate to detect the presence of an acid phosphatase marker in the urine sample, such that failure to detect the acid phosphatase marker indicates the sample is invalid;
• a long-duration counterfeit urine assay that utilizes p-nitrophenyl phosphate to detect the presence of an alkaline phosphatase marker in the urine sample, such that failure to detect the alkaline phosphatase marker indicates the sample is invalid;
• a Specific Gravity Index assay that utilizes β-Galactosidase and o-nitrophenylgalactoside to measure a combined amount of sodium and potassium in the urine sample to obtain a Specific Gravity Index value, such that a Specific Gravity Index value that is outside of a pre-determined range indicates the sample is invalid;
• a creatinine assay that utilizes alkaline picrate to measure the amount of creatinine in the urine sample, such that an amount of creatinine outside of a pre-determined range indicates the sample is invalid;
• and
• a pH assay that bi-chromatically measures pH of the urine sample, such that a pH in the acid range presents a different color than a pH in the alkaline range;
• determining if at least one of the SUD Diagnostic Panel assays indicate the urine sample is invalid, thereby providing an objective indication of SUD.