Evaluation of proteinuria in children
- Olivia Gillion Boyer, MD, PhD
Olivia Gillion Boyer, MD, PhD
- Associate Professor of Pediatrics
- Pediatric Nephrology, Imagine Institute, Paris-Descartes University, Hôpital Necker - Enfants Malades, Paris, France
- Section Editors
- Patrick Niaudet, MD
Patrick Niaudet, MD
- Section Editor — Pediatric Nephrology
- Professor of Pediatrics
- Hôpital Necker-Enfants Malades, Paris, France
- Jan E Drutz, MD
Jan E Drutz, MD
- Section Editor — General Pediatrics
- Professor of Pediatrics
- Baylor College of Medicine
Proteinuria as a marker of renal disease has been well established. The dilemma that faces the primary care clinician is to differentiate the child with transient or other benign forms of proteinuria from the child with proteinuria from renal disease.
An overview of the evaluation of proteinuria in children will be presented here. Some related issues, including the mechanisms of proteinuria, are discussed in more detail elsewhere. (See "Assessment of urinary protein excretion and evaluation of isolated non-nephrotic proteinuria in adults".)
PATHOPHYSIOLOGY AND CLASSIFICATION
Normal protein excretion — Urinary protein excretion in the normal child is less than 100 mg/m2 per day or a total of 150 mg per day. In neonates, normal urinary protein excretion is higher, up to 300 mg/m2, because of reduced reabsorption of filtered proteins.
Approximately one-half of normal protein excretion consists of proteins secreted by tubular epithelium, mostly Tamm-Horsfall protein (uromodulin). The other half consists of plasma proteins including albumin, which accounts for approximately 40 percent of the total urinary protein, and low molecular weight (LMW) proteins, such as beta-2 microglobulin and amino acids.
The normally low rate of urinary protein excretion is due to two factors:
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- Hogg RJ, Portman RJ, Milliner D, et al. Evaluation and management of proteinuria and nephrotic syndrome in children: recommendations from a pediatric nephrology panel established at the National Kidney Foundation conference on proteinuria, albuminuria, risk, assessment, detection, and elimination (PARADE). Pediatrics 2000; 105:1242.
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- Yang CY, Chen FA, Chen CF, et al. Diagnostic Accuracy of Urine Protein/Creatinine Ratio Is Influenced by Urine Concentration. PLoS One 2015; 10:e0137460.
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- PATHOPHYSIOLOGY AND CLASSIFICATION
- Normal protein excretion
- Abnormal protein excretion
- - Glomerular proteinuria
- - Tubular proteinuria
- - Overflow proteinuria
- MEASUREMENT OF URINARY PROTEIN
- Urine dipstick
- Sulfosalicylic acid test
- Quantitative assessment
- - Spot urine sample
- - Timed 24-hour urine collection
- Qualitative assessment
- APPROACH TO THE CHILD WITH PROTEINURIA
- History and physical examination
- Asymptomatic child
- - Indications for renal biopsy
- Symptomatic child
- SUMMARY AND RECOMMENDATIONS