- Protein may be found in the urine of healthy children.
- The term proteinuria is used to indicate urinary protein excretion beyond the upper limit of normal (100 mg/m2/day or 4 mg/m2/h in children and 150 mg/day in adults).
- Nephrotic range proteinuria >1,000 mg/m2/day or 40 mg/m2/h
- Nephrotic syndrome: nephrotic-range proteinuria with edema and hypoalbuminemia (<2.5 g/dL)
- Microalbuminuria: elevated urinary excretion of albumin (30–300 mg/g albumin/creatinine ratio or 30–300 mg/day). Currently, it is only used to indicate kidney disease in those with diabetes mellitus.
- Persistent or fixed proteinuria
- Urinary dipstick ≥1+ in the first morning urine specimen on ≥3 samples >1 week apart
- Requires prompt referral to nephrology
- Transient proteinuria
- Proteinuria absent on subsequent urine examinations
- It is not usually associated with clinically significant underlying renal disease.
- Often associated with high fever, cold stress, dehydration, and exercise
- Orthostatic or postural proteinuria
- Elevated protein excretion when the patient is upright that normalizes when patient is supine
- The most common cause of fixed or transient proteinuria in childhood and adolescence
- Proteinuria rarely exceeds 1 g/m2/day.
- Benign condition
- Persistent or fixed proteinuria
- Normally, ∼50% urinary proteins are derived from tissue proteins and proteins from cells lining the urinary tract (i.e., Tamm-Horsfall protein).
- Proteinuria may be the result of glomerular proteinuria or tubular proteinuria.
- Glomerular proteinuria
- An increased permeability of the glomeruli to the passage of plasma proteins
- Normally may range from <1 to >30 mg/day
- Large amounts of glomerular proteinuria may be found in the context of edema and hypoalbuminemia (nephrotic syndrome).
- If there is hypertension, abnormal glomerular filtration rate, and hematuria, there may be nephritis as well.
- Tubular proteinuria
- Decreased reabsorption of low-molecular-weight proteins by the proximal renal tubules
- Rarely >1 g/day and is not associated with edema.
- The major marker is urinary beta-2-microglobulin.
- It may be associated with other defects of proximal tubular function (e.g., renal tubular acidosis [RTA], glucosuria, phosphaturia, aminoaciduria) and tubular interstitial processes.
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Cabana, Michael D., editor. "Proteinuria." Select 5-Minute Pediatrics Topics, 7th ed., Wolters Kluwer Health, 2015. Medicine Central, im.unboundmedicine.com/medicine/view/Select-5-Minute-Pediatric-Consult/14209/all/Proteinuria.
Proteinuria. In: Cabana MDM, ed. Select 5-Minute Pediatrics Topics. Wolters Kluwer Health; 2015. https://im.unboundmedicine.com/medicine/view/Select-5-Minute-Pediatric-Consult/14209/all/Proteinuria. Accessed June 4, 2023.
Proteinuria. (2015). In Cabana, M. D. (Ed.), Select 5-Minute Pediatrics Topics (7th ed.). Wolters Kluwer Health. https://im.unboundmedicine.com/medicine/view/Select-5-Minute-Pediatric-Consult/14209/all/Proteinuria
Proteinuria [Internet]. In: Cabana MDM, editors. Select 5-Minute Pediatrics Topics. Wolters Kluwer Health; 2015. [cited 2023 June 04]. Available from: https://im.unboundmedicine.com/medicine/view/Select-5-Minute-Pediatric-Consult/14209/all/Proteinuria.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Proteinuria ID - 14209 ED - Cabana,Michael D, BT - Select 5-Minute Pediatrics Topics UR - https://im.unboundmedicine.com/medicine/view/Select-5-Minute-Pediatric-Consult/14209/all/Proteinuria PB - Wolters Kluwer Health ET - 7 DB - Medicine Central DP - Unbound Medicine ER -