Abstract
Purpose::
TINU is a specific form of uveitis that is unfamiliar to most ophthalmologists. In a chart review TINU was present in 32% of patients with bilateral anterior uveitis with sudden onset less than 20 years old. To diagnose TINU, the highest grade of certainty is gained by a positive kidney biopsy. As this is a very invasive procedure less invasive tests are needed. Urinary beta-2microglobulin (Ub2MG) is a marker for tubular dysfunction which has been shown to be elevated in patients with TINU with normal renal function but abnormal renal biopsy (Goda et al).
Methods::
Beginning January 2006 we prospectively obtained Ub2MG levels in all children (<18 years) with bilateral, sudden onset anterior uveitis attending our pediatric uveitis clinic for the first time. Normal values were defined as less than 0.33 mg/l. Other clinical criteria as defined by Mandeville et al were used to grade the certainty of the diagnosis. We compared with a healthy control group of children with strabismus from the neuroophthalmologic clinic and a group of children with other uveitis subsets.
Results::
Ten children with bilateral, sudden onset anterior uveitis attended our clinic since January 2006 (total 59 new children in this time period). We tested nine for Ub2MG; one was excluded because he came with the certain diagnosis of TINU from a nephrologist. Of these nine, 6 showed clinical criteria suggesting possible (n=4) to probable TINU (n=2). In all 6 patients, but one, Ub2MG levels were elevated to a mean value of 0.73 mg/l (SD = 0.55). Conversely, the three patients without clinical criteria for TINU, all had normal Ub2MG levels (mean 0.16 mg/l, SD = 0.08). There was a positive correlation between clinical criteria and Ub2MG levels (Spearman r = 0.68, p=0.05).We determined Ub2MG in 11 healthy children; only two had slightly elevated levels (mean = 0.25 mg/l, SD = 0.13). Of two children with other uveitis subtypes where Ub2MG was obtained, none had elevated levels (0.08 and 0.32 mg/l).
Conclusions::
Our preliminary results indicate that TINU may be present in 60% (5+1/10) of children with bilateral, anterior sudden onset uveitis, and 10% (6/59) of all new children with uveitis seen in 11 months, by far a higher number than previously assumed. Ub2MG seems to be an non-invasive diagnostic marker to suggest the diagnosis of TINU. Obviously, this depicts a tertiary referral center and not frequencies in the population.
Keywords: uveitis-clinical/animal model