22 - Proteinuria

Abstract

Proteinuria is a frequent laboratory finding among children and adolescents in either an outpatient clinic or inpatient setting. It can be identified as either a transient or persistent finding. The presence of proteinuria may reflect a benign finding or suggest disorders of renal function or structure. This distinction should be evaluated through taking a detailed history and performing a thorough physical examination, which includes microscopic urine evaluation and ordering the necessary laboratory investigations to assess renal function or biomarkers of renal disease. The gold standard for quantification of proteinuria is the 24-hour urine collection, but a simple starting point assessing a spot urinary protein-to-creatinine ratio offers a practical diagnostic approach in children. Initial evaluation can be coordinated in the primary care office, but referral to a nephrologist should be considered in the following circumstances: persistent nonorthostatic proteinuria, a family history of renal disease, and comorbid systemic disease including hypertension, hematuria, edema, and abnormal renal function suggested by elevated BUN or creatinine levels.