Proteinuria: Difference between revisions

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(Created page with "<section begin="clinical biochemistry" /><section begin="pathophysiology" />'''Proteinuria''' refers to pathological amounts of protein in the urine, defined as urinary protein content of > 150 mg per day. Physiologically, 50 - 150 mg protein is excreted in urine per day, most of which secreted by the tubuli with only small amounts filtered through the glomeruli. 99% of filtered proteins are reabsorbed in the tubuli. Most normal plasma proteins are not filtered in the g...")
 
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<section begin="clinical biochemistry" /><section begin="pathophysiology" />'''Proteinuria''' refers to pathological amounts of protein in the urine, defined as urinary protein content of > 150 mg per day. Physiologically, 50 - 150 mg protein is excreted in urine per day, most of which secreted by the tubuli with only small amounts filtered through the glomeruli. 99% of filtered proteins are reabsorbed in the tubuli.
<section begin="urology" /><section begin="clinical biochemistry" /><section begin="pathophysiology" />'''Proteinuria''' refers to pathological amounts of protein in the urine, defined as urinary protein content of > 150 mg per day. Physiologically, 50 - 150 mg protein is excreted in urine per day, most of which secreted by the tubuli with only small amounts filtered through the glomeruli. 99% of filtered proteins are reabsorbed in the tubuli.


Most normal plasma proteins are not filtered in the glomeruli because they are too large for the glomerular pores and they are negative, just like the filter surface. The small amount of protein that is filtered are small in size (below 65 kD) and are reabsorbed by proximal tubular cells where they are metabolized.
Most normal plasma proteins are not filtered in the glomeruli because they are too large for the glomerular pores and they are negative, just like the filter surface. The small amount of protein that is filtered are small in size (below 65 kD) and are reabsorbed by proximal tubular cells where they are metabolized.
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Postrenal proteinuria (300 - 1000 mg/day) can occur due to [[urinary tract infection]].
Postrenal proteinuria (300 - 1000 mg/day) can occur due to [[urinary tract infection]].
 
<section end="urology" />
== Classification ==
== Classification ==
Proteinuria can be classified according to quantity of proteins in the urine. Because albumin is the most abundant protein excreted in urine, we usually classify proteinuria by the amount of albumin. Urinary albumin excretion varies throughout the day and depends on how concentrated the urine is. Measuring the ''albumin/creatinine ratio'' (ACR) rather than the albumin concentration mitigates the latter of these issues and is therefore used rather than urinary albumin concentration, but the gold standard is 24-hour measurement of urinary protein concentration
Proteinuria can be classified according to quantity of proteins in the urine. Because albumin is the most abundant protein excreted in urine, we usually classify proteinuria by the amount of albumin. Urinary albumin excretion varies throughout the day and depends on how concentrated the urine is. Measuring the ''albumin/creatinine ratio'' (ACR) rather than the albumin concentration mitigates the latter of these issues and is therefore used rather than urinary albumin concentration, but the gold standard is 24-hour measurement of urinary protein concentration
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|>1000 mg/dL
|>1000 mg/dL
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<section begin="urology" />
== Consequences ==
== Consequences ==
Proteinuria is a sign of pathology, usually kidney damage. Glomerular filtration of protein damages the glomeruli further and so eventually causes progressive kidney damage. Proteinuria, even small amounts, is associated with [[cardiovascular disease]]. Massive proteinuria (especially nephrotic proteinuria) can cause hypoproteinaemia, which may affect muscle growth, immune system function, and may cause oedema.<section end="pathophysiology" /><section end="clinical biochemistry" />
Proteinuria is a sign of pathology, usually kidney damage. Glomerular filtration of protein damages the glomeruli further and so eventually causes progressive kidney damage. Proteinuria, even small amounts, is associated with [[cardiovascular disease]]. Massive proteinuria (especially nephrotic proteinuria) can cause hypoproteinaemia, which may affect muscle growth, immune system function, and may cause oedema.<section end="pathophysiology" /><section end="clinical biochemistry" /><section end="urology" />
[[Category:Pathophysiology]]
[[Category:Pathophysiology]]
[[Category:Nephrology]]
[[Category:Nephrology]]