title: Urinary β2-Microglobulin Testing in Pediatric Uveitis: A Case Report of a 9-Year-Old Boy with Renal and Ocular Sarcoidosis.
abstract: We present here a case of a 9-year-old boy with bilateral anterior uveitis and an extremely elevated urinary β2-microglobulin level (25,400 μg/l). The normal range for urinary excretion of β2-microglobulin is 0-300 μg/l. In patients with tubulointerstitial nephritis and uveitis syndrome (TINU), elevations typically range from 1,260 to 5,160 μg/l. Renal biopsy was pursued, and significant granulomatous interstitial nephritis consistent with sarcoidosis was identified. Systemic immune modulation was required for control of ocular inflammation. This case highlights the importance of urinary β2-microglobulin testing in the pediatric patient uveitis population, and additionally the need to pursue kidney biopsy in the presence of extreme elevations in urinary β2-microglobulin to differentiate between TINU and sarcoidosis.
authors: Department of Ophthalmology, University of Washington Medical School, Wash., USA.
authors: Kathryn L
authors: KL
authors: Pepple
authors: Department of Ophthalmology, University of Washington Medical School, Wash., USA.
authors: Deborah L
authors: DL
authors: Lam
authors: Department of Pathology, University of Washington Medical School, Wash., USA ; Department of Laboratories, Seattle Children's Hospital, Seattle, Wash., USA.
authors: Laura S
authors: LS
authors: Finn
authors: Department of Ophthalmology, University of Washington Medical School, Wash., USA ; Department of Pathology, University of Washington Medical School, Wash., USA ; Department of Biological Structure, University of Washington Medical School, Wash., USA.
authors: Russell
authors: R
authors: Van Gelder
keywords: Juvenile idiopathic arthritis; Sarcoidosis; Tubulointerstitial nephritis and uveitis syndrome; Uveitis; β2-Microglobulin