title: Urine processing impacts uric acid level in HIV-infected adults: implications for diagnosing tenofovir-associated proximal tubulopathy.
abstract: Urine specimens are valuable to investigate kidney disease and antiretroviral nephrotoxicity. We observed large rust-colored pellets in some urine specimens after overnight storage at 4°C. Testing of supernatant under varying conditions demonstrated that this phenomenon reflects supersaturation and precipitation of uric acid in samples with high uric acid concentration. Delays in processing, even with refrigeration, may decrease the sensitivity of urine uric acid testing, with implications for the evaluation of proximal tubulopathy related to tenofovir.
authors.affiliation: Mount Sinai School of Medicine, The Samuel F. Bronfman Department of Medicine, Division of Nephrology, New York, NY 10029 USA.
authors.forename: Mathew T
authors.initials: MT
authors.lastname: Hotta
authors.forename: Erin
authors.initials: E
authors.lastname: Broderick
authors.forename: Christina M
authors.initials: CM
authors.lastname: Wyatt
mesh_terms: D016263:AIDS-Associated Nephropathy / Q000139:chemically induced / Q000175:diagnosis*; D000225:Adenine / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D000328:Adult; D019380:Anti-HIV Agents / Q000009:adverse effects* / Q000627:therapeutic use; D015658:HIV Infections / Q000150:complications* / Q000188:drug therapy*; D006801:Humans; D063065:Organophosphonates / Q000009:adverse effects* / Q000627:therapeutic use; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods*; D000068698:Tenofovir; D013997:Time Factors; D014527:Uric Acid / Q000652:urine*
chemical_list: D019380:Anti-HIV Agents; D063065:Organophosphonates; D014527:Uric Acid; D000068698:Tenofovir; D000225:Adenine