The child with protein in their urine is a common finding in pediatric practice. Protein may be found in the urine of healthy children. The incidence increases with age and the majority of protein is albumin. 

Mechanism of Proteinuria

1. Increased glomerular filtration. The protein must pass through the glomerular capillary wall. 
1. Nephrotic Syndrome- minimal change disease and focal glomerulosclerosis
2. Glomerulonephritis
3. Drugs
2. Decreased tubular reabsorption. Most filtered protein is reabsorbed proximally. With tubular damage, there will be increased protein in the urine
1. Transport defects- Fanconi's Syndrome, Cystinosis
2. Toxins- Penicillins, Heavy metals, Aminoglycosides, old tetracycline
3. Ischemic injury- shock, ATN, Endotoxemia
4. Obstructive uropathy, Polycystic disease
3. Increased secretion- normally some protein is secreted but may increase with exercise, acute renal failure, transplant rejection, and stones.

1. Dipsticks- Very sensitive and changes color secondary to reaction of tetrabromophenol with amino acids. Have false positives with ph >8, concentrated urine, long immersion time, or presence of wbcs or bacteria. Reading of 1+ needs to rechecked and if continues positive, timed collections should be done.
2. Timed Collection- technically may be difficult. Doesn't allow for diurnal variations and effect of activity on proteinuria. In adults, >150 mg. 24 hours is positive. In children, > 4 mg./metered squared/hour is positive.
3. Protein/Creatinine ratio.-Helpful screening tool if timed collection is difficult. Use a randomly collected urine in an ambulating patient. < .5 in less than 2 year old, <.2 in older child. > 3 is in the nephrotic range

1. History
1. Family history 
2. UTI symptoms
3. Drug exposure
4. Growth history
5. Recent infections
6. Hepatitis B status and HIV risk factors
7. Rashes
8. joint symptoms
2. Physical Examination
1. Edema
2. Blood pressure
3. Skin examination
4. Joints
5. Chronically ill appearing
3. If there is repeated >1+ protein on a dipstick, in the absence of significant history, physical findings, and hematuria, a supine urine should be collected. The child should empty their bladder before going to sleep and the first morning urine, while still supine, should be collected. If this is free of protein, another urine should be tested while the child is up and about. If this is positive, the diagnosis of orthostatic proteinuria may be made. The child should have this test repeated a few times over the next year. If both specimens contain protein, further evaluation should be done including:
1. BUN, Creatinine, and Electrolytes
2. Complement levels
3. ASO titers and Lupus serology (if glomerulnephritis suspected)
4. Nephrology consult

1. Exercise- should recheck after a few days of inactivity
2. Fever- recheck when the child is afebrile
3. Postural or orthostatic proteinuria- very common especially in adolescence. Picked up on routine screen and patient is asymptomatic, the physical examination including BP is normal, and there is no red blood cells in the urine. 

1. Ahmed Z and Lee J. Asymptomatic Urinary Abnormalities: Hematuria and Proteinuria. Medical Clinics of North America. 1997; 81(3):641-652.
2. Cruz, Carmina and Spitzer, Adrian. When you find protein or blood in the urine. Contemporary Pediatrics. September 1998.
3. Mahan JD, Turman MA and Mentser MI. Evaluation of Hematuria, Proteinuria and Hypertension in Adolescents. Pediatric Clinics of North America. 1997; 44(6):1573-1589.
4. Hogg.,R  Evaluation and Management of Proteinuria and Nephrotic Syndrome. Pediatrics June 2000