出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/08/07 02:02:15」(JST)
| Proteinuria | |
|---|---|
| Classification and external resources | |
| Specialty | Nephrology |
| ICD-10 | R80 |
| ICD-9-CM | 791.0 |
| DiseasesDB | 25320 |
| eMedicine | med/94 |
| Patient UK | Proteinuria |
| MeSH | D011507 |
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[edit on Wikidata]
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Proteinuria (/proʊtiːˈnʊəriə/ or /proʊtiːˈnjʊəriə/; 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, pneumaturia (air bubbles in the urine) due to a fistula,[2] 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).[3][4]
Also leptin administration to normotensive Sprague Dawley rats during pregnancy significantly increases urinary protein excretion [5]
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.
Proteinuria may be a feature of the following conditions:[6]
| Protein dipstick grading | ||
|---|---|---|
| Designation | Approx. amount | |
| Concentration[10] | Daily[11] | |
| 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,[12] 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.[6][13] 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][14] 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.[15]
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.[16]
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.[17] 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.[18]
It is possible to analyze urine samples in determining albumin, haemoglobin and myoglobin with an optimized MEKC method.[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.
Components and results of urine tests (CPT 81000–81099; R80–R82, 791)
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| リンク元 | 「尿蛋白」 |
| 関連記事 | 「In」 |
| 尿蛋白 | |
| 150mg/日未満 | 健常者の基準(15mg/dL 10dL) |
| 300mg/日 | 糖尿病性腎症の顕性タンパク尿の定義 |
| 1000mg/日 | 起立性タンパク尿や熱性タンパク尿などの良性タンパク尿の上限 (血尿があるときは500mg/日のタンパク尿で腎疾患を考慮) |
| 1500-3000mg/日 | 尿細管障害によるタンパク尿の限界で、これ以上は糸球体疾患と考える。 |
| 分子量 (kDa) |
糖質 (%) |
機能 | |
| β2ミクログロブリン | 11 | 0 | 構造タンパク・HLAのL鎖 |
| リゾチーム | 15 | 0 | 消化殺菌酵素 |
| レチノール結合蛋白 | 20 | 0 | ビタミンA担体 |
| 免疫グロブリンL鎖 | 22 | 0 | 構造タンパク質 |
| α1ミクログロブリン | 30 | 20 | 輸送担体 |
| α1酸性糖タンパク | 44 | 38 | 急性相蛋白 |
| アルブミン | 67 | 0 | 膠質浸透圧維持、輸送担体 |
| 煮沸法 | スルフォサリチル酸法 | 試験紙法 | |
| 原理 | 蛋白質の熱変性による混濁 (特異性が高い) |
蛋白と酢酸の不溶性塩による混濁 | 指示薬の蛋白誤差を利用 |
| 感度 | 5mg/dl | 1.5-2mg/dl (鋭敏) |
5-20 mg/dl |
| 偽陽性 | ヨード造影剤 トルブタミド ペニシリン系抗菌薬 セフェム系抗菌薬 |
リン酸塩を含むアルカリ性尿 第4級アンモニウム化合物 (防腐剤、洗浄剤)EDTAのことか？ | |
| 偽陰性 | リン酸塩を含むアルカリ性尿 | 低分子タンパク尿(BJP等) | |