# A Case of Tubulointerstitial Nephritis With Uveitis Diagnosed From Isolated Glucosuria Detected During School Urinary Screening

## TL;DR

A 12-year-old girl was diagnosed with TINU after glucosuria was found during a school screening, highlighting the importance of considering kidney disease beyond diabetes.

## Contribution

This case highlights the importance of considering TINU in children with isolated glucosuria and normal urine protein.

## Key findings

- Glucosuria was detected in a 12-year-old girl during a school screening, with no diabetes indicators.
- The patient was diagnosed with TINU after presenting with uveitis three months later.
- Low-molecular-weight protein in urine can be missed by standard dipstick tests, emphasizing the need for detailed evaluation.

## Abstract

We report a case of tubulointerstitial nephritis with uveitis (TINU) diagnosed from isolated glucosuria detected during school urinary screening.

The patient was a 12-year-old girl in whom glucosuria was detected during school urinary screening using a dipstick; however, urinary protein and occult blood were negative. There were no preceding symptoms of infection or medication. The patient visited the Fujita Health University Okazaki Medical Center two weeks after the school urinary screening for further examination. No edema or skin rash was observed. A urine test showed urinary glucose was positive and urinary β2-microglobulin was high; other values were almost normal. Mild renal dysfunction was observed. There was no hyperglycemia or high HbA1c level; therefore, diabetes mellitus was ruled out. Various autoantibody tests were negative, and the angiotensinogen-converting enzyme level was within the normal range. The patient was clinically diagnosed with idiopathic tubulointerstitial nephritis without a renal biopsy. Renal dysfunction tended to improve gradually after the first visit. Three months after the first visit, conjunctival congestion appeared in the right eye, and the patient was diagnosed with uveitis and eventually with TINU.

When performing detailed examinations for urinary glucose, it is necessary to differentiate kidney disease as well as diabetes mellitus. Moreover, it is necessary to recognize that even if the urine dipstick test is negative for protein, it may be positive for low-molecular-weight protein.