Benzodiazepine in a urine specimen without drug metabolites

41-year-old Hispanic woman. Chief Complaint: Pain in the neck, joints, and shoulders that started in August 2013. History of Present Illness: The patient has a history of psychiatric illness. Her primary care physician from an outside facility had prescribed alprazolam (Xanax) to treat her depression. The patient reported that in 2011 she experienced pain in the right side of her back and was diagnosed with sciatica. In addition, she was diagnosed with systemic lupus erythematosus (SLE) based on a positive finding for antinuclear antibodies (ANA) and double-stranded DNA (ds-DNA). She had not consulted a rheumatologist before this visit, nor had she received any medication for these conditions. Her recent history of symptoms included photosensitivity, painful aphthous ulcers, transient rashes, joint pain, myalgias, and bruising. The results of the most recent evaluation of her SLE serology revealed negative ANA and ds-DNA results. The current medications that the patient has been prescribed at Santa Clara Valley Medical Center include lamotrigine (Lamictal), sertraline (Zoloft), and gabapentin (Neurontin). In April 2014, the patient requested additional pain medication, such as hydrocodone/acetaminophen (Norco), during her physician visit. Consequently, as part of her pain management therapy agreement to ensure compliance,(1) she was subjected to a urine toxicology drug screening. At this time, her urine specimen, from an unwitnessed collection, tested positive for benzodiazepines using the Syva EMIT immunoassay (Siemens AG, Munich, Germany) at the cutoff of 200 ng/mL. However, results of a confirmatory test conducted via gas chromatography-mass spectrometry (GC/MS) did not identify any benzodiazepine metabolites in her urine but instead revealed the presence of a parent drug, alprazolam. Further, the same specimen tested positive for metronidazole. A visual inspection of the specimen revealed crystals on the bottom of the cup. In December 2013, this patient had tested positive for α-hydroxyalprazolam (an alprazolam metabolite; limit of detection, 10 ng/mL) and methamphetamine. At that time, she explained her positive urine-drug-test result by stating that "somebody had put something in my drink." Family history: Her father has been diagnosed with gout, knee osteoarthritis, and enlarged heart. Her brother has been diagnosed with clinical depression. Social history: Divorced; 3 children in the custody of their father; reported having smoked 0.5 packs of cigarettes per day for 20 years; denied any alcohol intake or illicit drug use.