Malaise, Weight Loss, and Acute Kidney Injury in a 13-year-old Girl.

1. Amanda J. Clark, MD* 2. Lauren Matevish, MD† 3. Marta Hernanz-Schulman, MD‡ 4. Emily F. Mason, MD, PhD§ 5. Tracy E. Hunley, MD¶ 1. *Division of Pediatric Nephrology, Boston Children’s Hospital, Boston, MA 2. †Vanderbilt University School of Medicine, Nashville, TN 3. ‡Division of Diagnostic Imaging, Monroe Carell Jr. Children’s Hospital at Vanderbilt, Nashville, TN 4. §Division of Hematopathology, Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN 5. ¶Division of Pediatric Nephrology, Monroe Carell Jr. Children’s Hospital at Vanderbilt, Nashville, TN A 13-year-old girl presents to the pediatric clinic with complaints of malaise, progressive nausea, emesis, and poor oral intake since removal of her wisdom teeth 1 month earlier. In that month she completed a course of clindamycin to treat a suspected postoperative oral infection. Review of systems revealed a 10-lb unintentional weight loss, intermittent joint pain, and decreased urine output. She denies any fevers. Vital signs are normal other than blood pressure of 130/72 mm Hg and pulse of 121 beats/min. Physical examination shows a tired-appearing but polite young lady with a slightly enlarged, asymmetrical thyroid and otherwise normal examination findings. A complete blood cell count shows a hemoglobin level of 11.6 g/dL (116 g/L), a platelet count of 0.153 × 103/mcL (0.153 × 109/L), and a white blood cell count of 5.3/µL (0.01 × 109/L) with a normal differential cell count. Thyrotropin and free T4 levels are normal. Her sedimentation rate is 43 mm/hr. A complete metabolic panel reveals normal sodium, potassium, chloride, carbon dioxide, albumin, total protein, and calcium levels. Her creatinine level is elevated to 2.29 mg/dL (202.44 µmol/L), blood urea nitrogen level is 36 mg/dL (12.9 mmol/L), total bilirubin level is 1.1 mg/dL (18.8 µmol/L), aspartate aminotransferase level is 53 U/L (0.89 µkat/L), and alanine aminotransferase level is 37 U/L (0.62 µkat/L). The urine pregnancy test result is negative. Dipstick urinalysis reveals yellow urine, specific gravity of 1.010, pH 5.5, moderate blood, trace protein, positive nitrites, negative leukocyte esterase, and small bilirubin. Urine microscopy is striking for numerous uric acid crystals (Figs 1 and 2). Additional serum testing and imaging lead to the diagnosis. Figure 1. Urine microscopy at 10× magnification showing the striking presence of crystalluria. Figure 2. Urine microscopy at 40× magnification again showing striking crystalluria with several morphologies of uric acid crystal, including diamonds (thin arrow), rhomboid …