Tubulointerstitial nephritis and uveitis syndrome
B. Order urinalysis and urinary β2-microglobulin test
Starting topical treatment with corticosteroids and cycloplegic eye drops without further investigations (choice A) would not be the preferred answer because abnormal kidney function warrants further investigations. Indeed in this case, urinalysis and urinary β2-microglobulin (β2M) testing (choice B) revealed normoglycemic glycosuria and increased β2M levels (6.6 mg/24 h; reference range, 0.02-0.37), suggestive of tubulointerstitial nephritis and uveitis syndrome (TINU).1 Magnetic resonance imaging (MRI) of the brain and orbits (choice C) was not indicated as urgent investigation, because the observed optic disc edema was most likely secondary to the intraocular inflammation rather than a central nervous system dysfunction. However, MRI of the brain and orbits was performed electively and did not show any abnormalities. Finally, observation (choice D) in symptomatic and active uveitis is not recommended.