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Classification and external resources
Specialty Nephrology DiseasesDB = 25320
ICD-10 R80
ICD-9-CM 791.0
eMedicine med/94
Patient UK Proteinuria
MeSH D011507
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Proteinuria (/prtˈnʊəriə/ or /prtˈnjʊəriə/; from protein and urine) means the presence of an excess of serum proteins in the urine. The excess protein in the urine often causes the urine to become foamy, although foamy urine may also be caused by bilirubin in the urine (bilirubinuria),[1] retrograde ejaculation,[2] pneumaturia (air bubbles in the urine) due to a fistula,[3] or drugs such as pyridium.[1]


There are three main mechanisms to cause proteinuria:

Proteinuria can also be caused by certain biological agents, such as bevacizumab (Avastin) used in cancer treatment, or by excessive fluid intake (drinking in excess of 4 litres of water per day).[4][5]

Also leptin administration to normotensive Sprague Dawley rats during pregnancy significantly increases urinary protein excretion [6]

Proteinuria may be a sign of renal (kidney) damage. Since serum proteins are readily reabsorbed from urine, the presence of excess protein indicates either an insufficiency of absorption or impaired filtration. People with diabetes may have damaged nephrons and develop proteinuria. The most common cause of proteinuria is diabetes, and in any person with proteinuria and diabetes, the etiology of the underlying proteinuria should be separated into two categories: diabetic proteinuria versus the field.

With severe proteinuria, general hypoproteinemia can develop which results in diminished oncotic pressure. Symptoms of diminished oncotic pressure may include ascites, edema and hydrothorax.

Conditions with proteinuria as a sign

Proteinuria may be a feature of the following conditions:[7]

Conditions with proteinuria consisting mainly of Bence-Jones proteins as a sign


Protein dipstick grading
Designation Approx. amount
Concentration[11] Daily[12]
Trace 5–20 mg/dL
1+ 30 mg/dL Less than 0.5 g/day
2+ 100 mg/dL 0.5–1 g/day
3+ 300 mg/dL 1–2 g/day
4+ More than 300 mg/dL More than 2 g/day

Conventionally, proteinuria is diagnosed by a simple dipstick test, although it is possible for the test to give a false negative reading,[13] even with nephrotic range proteinuria if the urine is dilute.[citation needed] False negatives may also occur if the protein in the urine is composed mainly of globulins or Bence-Jones proteins because the reagent on the test strips, bromophenol blue, is highly specific for albumin.[7][14] Traditionally, dipstick protein tests would be quantified by measuring the total quantity of protein in a 24-hour urine collection test, and abnormal globulins by specific requests for protein electrophoresis.[1][15] Trace results may be produced in response to excretion of Tamm-Horsfall mucoprotein.

More recently developed technology detects human serum albumin (HSA) through the use of liquid crystals (LCs). The presence of HSA molecules disrupts the LCs supported on the AHSA-decorated slides thereby producing bright optical signals which are easily distinguishable. Using this assay, concentrations of HSA as low as 15 µg/mL can be detected.[16]

Alternatively the concentration of protein in the urine may be compared to the creatinine level in a spot urine sample. This is termed the protein/creatinine ratio. The 2005 UK Chronic Kidney Disease guidelines states protein/creatinine ratio is a better test than 24 hour urinary protein measurement. Proteinuria is defined as a protein/creatinine ratio greater than 45 mg/mmol (which is equivalent to albumin/creatinine ratio of greater than 30 mg/mmol or approximately 300 mg/g) with very high levels of proteinuria having a ratio greater than 100 mg/mmol.[17]

Protein dipstick measurements should not be confused with the amount of protein detected on a test for microalbuminuria which denotes values for protein for urine in mg/day versus urine protein dipstick values which denote values for protein in mg/dL. That is, there is a basal level of proteinuria that can occur below 30 mg/day which is considered non-pathology. Values between 30–300 mg/day are termed microalbuminuria which is considered pathologic.[18] Urine protein lab values for microalbumin of >30 mg/day correspond to a detection level within the "trace" to "1+" range of a urine dipstick protein assay. Therefore, positive indication of any protein detected on a urine dipstick assay obviates any need to perform a urine microalbumin test as the upper limit for microalbuminuria has already been exceeded.[19]


Treating proteinuria mainly needs proper diagnosis of the cause. The most common cause is diabetic nephropathy; in this case, proper glycemic control may slow the progression. Medical management consists of angiotensin converting enzyme (ACE) inhibitors, which are typically first-line therapy for proteinuria. In patients whose proteinuria is not controlled with ACE inhibitors, the addition of an aldosterone antagonist (i.e., spironolactone)[20] or angiotensin receptor blocker (ARB)[21] may further reduce protein loss. Caution must be used if these agents are added to ACE inhibitor therapy due to the risk of hyperkalemia. Proteinuria secondary to autoimmune disease should be treated with steroids or steroid-sparing agent plus the use of ACE inhibitors.

See also


  1. 1.0 1.1 1.2 URINALYSIS Ed Friedlander, M.D., Pathologist - Retrieved 2007-01-20
  2. foamy urine - Urology - MedHelp Retrieved 2007-01-20
  3. Pneumaturia at GPnotebook Retrieved 2007-01-20
  4. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  5. "Drinking too much water called latest threat to health". Montreal Gazette. January 2008.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  6. Hisham S. Ibrahim, Gabriele Ruth Anisah Froemming, Effat Omar, and Harbindar Jeet Singh " Leptin increases blood pressure and markers of endothelial activation during pregnancy in rats". BioMed Research International Journal. Vol 2013. Article ID 298401, 6 pages.
  7. 7.0 7.1 Simerville JA, Maxted WC, Pahira JJ (2005). "Urinalysis: a comprehensive review". American Family Physician. 71 (6): 1153–62. PMID 15791892. <templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  8. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
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  10. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  11. eMedicine > Proteinuria Author: Ronald J Kallen. Coauthor: Watson C Arnold. Updated: Apr 21, 2008
  12. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  13. Simerville JA, Maxted WC, and Pahira JJ. Urinalysis: A Comprehensive Review Am Fam Physician. 2005 Mar 15;71(6):1153-1162. Accessed 2 Feb 2012.
  14. Retrieved 2007-01-20
  15. Retrieved 2007-01-20
  16. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  17. "Identification, management and referral of adults with chronic kidney disease: concise guidelines" (PDF). UK Renal Association. 2005-09-27.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles> - see Guideline 4 Confirmation of proteinuria, on page 9
  18. "Urinary dipstick protein: a poor predictor of absent or severe proteinuria". PMID 8296815. Am J Obstet Gynecol. 1994 Jan;170(1 Pt 1):137-41.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  19. "The Urine Dipstick" (PDF). Georgia Regents University.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  20. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).
  21. Lua error in Module:Citation/CS1/Identifiers at line 47: attempt to index field 'wikibase' (a nil value).