Asymptomatic proteinuria in a child with recurrent urinary tract infections—questions

Excerpt

An 11-year-old girl with recurrent lower urinary tract infections was referred for asymptomatic proteinuria. She was reported to have been given antibacterial prophylaxis with trimethoprim–sulfamethoxazole for 1 year, which had been discontinued 6 months prior to presentation. The physical examination was completely normal. Her parents were first-degree relatives, and her 22-year-old brother had end stage renal disease. The results of previous imaging investigations, including renal ultrasonography, voiding cystourethrography, and ^99mTc-dimercaptosuccinic acid (DMSA) scintigraphy, were normal. Urinalysis showed 3+ proteinuria and normal sediment. Urine culture was sterile. Daily protein excretion was in the non-nephrotic range (25 mg/m²/h). Laboratory test results, including a complete blood count, creatinine, albumin, liver enzymes, and complement levels, were all normal. Given the family history, renal biopsy was performed to investigate hereditary nephropathies. Light and immunofluorescent microscopic examination of the renal biopsy did not reveal any abnormalities, but electron microscopy revealed the ultrastructural appearance shown in Fig. 1.

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