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*The authors acknowledge the special contributions of Anup Singh, MD, to prior edition.
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Healthy children normally have protein in their urine, with a protein excretion rate of <4 mg/m2/h or <100 mg/m2/day throughout childhood. The upper limit of normal protein excretion is up to 150 mg/day. Albumin, relatively small in molecular size, tends to be the dominant constituent, and Tamm-Horsfall protein, a mucoprotein produced in the distal tubule, makes up the remainder.
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Proteinuria in children can be transient, orthostatic, or pathologic. Transient proteinuria (often associated with fever or exercise) does not indicate underlying renal disease. Orthostatic proteinuria (elevated protein excretion when the subject is upright but normal protein excretion in recumbent position) occurs most commonly in school-aged children and rarely exceeds 1 g/m2/day. These patients do not have hematuria and have normal values of estimated glomerular filtration rate and C3 complement. Pathologic proteinuria is likely if proteinuria is associated with hematuria and/or the first morning urine protein-to-creatinine ratio is >0.2 in older children. Nephrotic-range proteinuria is defined as levels >40 mg/m2/h in 24 hours.
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Emergency Department Treatment and Disposition
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Take a complete history and physical ...