Proteinuria from first-morning urine in a child due to brace treatment for adolescent idiopathic scoliosis.

A first-morning urine test for screening urinary protein is important for distinguishing whether asymptomatic proteinuria, which is a common finding in school-aged children, is caused due to kidney disease or not. We report the case of a 12-year-old Japanese girl who was referred to our pediatric department for asymptomatic proteinuria detected during a school urinary screening. Proteinuria was found only on the first-morning urinalysis and not on the routine urinalysis. The patient had been diagnosed with adolescent idiopathic scoliosis and treated with a nighttime brace. As excess protein was not detected on urinalysis of the first-morning urine sample that was collected after a night without the brace, proteinuria due to the brace treatment for scoliosis was diagnosed. The present case revealed that brace treatment can cause proteinuria. Even if a first-morning urine is positive for protein, an unexpected cause can trigger asymptomatic proteinuria in a growing child.