Albuminuria

Last updated
Albuminuria
Other namesProteinuria
Specialty Nephrology
CausesDiabetes (Type 1 & Type 2), Hypertension, Urinary tract infections, Kidney Disease, Certain Medications

Albuminuria is a pathological condition wherein the protein albumin is abnormally present in the urine. It is a type of proteinuria. Albumin is a major plasma protein (normally circulating in the blood); in healthy people, only trace amounts of it are present in urine, whereas larger amounts occur in the urine of patients with kidney disease. For a number of reasons, clinical terminology is changing to focus on albuminuria more than proteinuria. [1]

Contents

Signs and symptoms

It is usually asymptomatic but whitish foam may appear in urine. Swelling of the ankles, hands, belly or face may occur if losses of albumin are significant and produce low serum protein levels (nephrotic syndrome).

Causes

The kidneys normally do not filter large molecules into the urine, so albuminuria can be an indicator of damage to the kidneys or excessive salt intake. It can also occur in patients with long-standing diabetes, especially type 1 diabetes. Recent international guidelines (KDIGO 2012) reclassified chronic kidney disease (CKD) based on cause, glomerular filtration rate category, and albuminuria category (A1, A2, A3). [1]

Causes of albuminuria can be discriminated between by the amount of protein excreted.

Diagnosis

The amount of protein being lost in the urine can be quantified by collecting the urine for 24 hours, measuring a sample of the pooled urine, and extrapolating to the volume collected.

Also a urine dipstick test for proteinuria can give a rough estimate of albuminuria. This is because albumin is by far the dominant plasma protein, and bromophenol blue the agent used in the dipstick is specific to albumin.

Treatment

Though there is some evidence that dietary interventions (to lower red meat intake) can be helpful in lowering albuminuria levels, [5] there is currently no evidence that low protein interventions correlate to improvement in kidney function. [6] Among other measures, blood pressure control, especially with the use of inhibitors of the renin-angiotensin-system, is the most commonly used therapy to control albuminuria.

Related Research Articles

<span class="mw-page-title-main">Proteinuria</span> Presence of an excess of serum proteins in the urine

Proteinuria is the presence of excess proteins in the urine. In healthy persons, urine contains very little protein, less than 150 mg/day; an excess is suggestive of illness. Excess protein in the urine often causes the urine to become foamy. Severe proteinuria can cause nephrotic syndrome in which there is worsening swelling of the body.

<span class="mw-page-title-main">Nephrotic syndrome</span> Kidney condition

Nephrotic syndrome is a collection of symptoms due to kidney damage. This includes protein in the urine, low blood albumin levels, high blood lipids, and significant swelling. Other symptoms may include weight gain, feeling tired, and foamy urine. Complications may include blood clots, infections, and high blood pressure.

<span class="mw-page-title-main">Kidney failure</span> Disease where the kidneys fail to adequately filter waste products from the blood

Kidney failure, also known as end-stage renal disease (ESRD), is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as either acute kidney failure, which develops rapidly and may resolve; and chronic kidney failure, which develops slowly and can often be irreversible. Symptoms may include leg swelling, feeling tired, vomiting, loss of appetite, and confusion. Complications of acute and chronic failure include uremia, hyperkalemia, and volume overload. Complications of chronic failure also include heart disease, high blood pressure, and anaemia.

<span class="mw-page-title-main">Urinalysis</span> Array of tests performed on urine

Urinalysis, a portmanteau of the words urine and analysis, is a panel of medical tests that includes physical (macroscopic) examination of the urine, chemical evaluation using urine test strips, and microscopic examination. Macroscopic examination targets parameters such as color, clarity, odor, and specific gravity; urine test strips measure chemical properties such as pH, glucose concentration, and protein levels; and microscopy is performed to identify elements such as cells, urinary casts, crystals, and organisms.

<span class="mw-page-title-main">Assessment of kidney function</span> Ways of assessing the function of the kidneys

Assessment of kidney function occurs in different ways, using the presence of symptoms and signs, as well as measurements using urine tests, blood tests, and medical imaging.

<span class="mw-page-title-main">Kidney disease</span> Damage to or disease of a kidney

Kidney disease, or renal disease, technically referred to as nephropathy, is damage to or disease of a kidney. Nephritis is an inflammatory kidney disease and has several types according to the location of the inflammation. Inflammation can be diagnosed by blood tests. Nephrosis is non-inflammatory kidney disease. Nephritis and nephrosis can give rise to nephritic syndrome and nephrotic syndrome respectively. Kidney disease usually causes a loss of kidney function to some degree and can result in kidney failure, the complete loss of kidney function. Kidney failure is known as the end-stage of kidney disease, where dialysis or a kidney transplant is the only treatment option.

<span class="mw-page-title-main">Glomerulonephritis</span> Term for several kidney diseases

Glomerulonephritis (GN) is a term used to refer to several kidney diseases. Many of the diseases are characterised by inflammation either of the glomeruli or of the small blood vessels in the kidneys, hence the name, but not all diseases necessarily have an inflammatory component.

<span class="mw-page-title-main">Diabetic nephropathy</span> Chronic loss of kidney function

Diabetic nephropathy, also known as diabetic kidney disease, is the chronic loss of kidney function occurring in those with diabetes mellitus. Diabetic nephropathy is the leading causes of chronic kidney disease (CKD) and end-stage renal disease (ESRD) globally. The triad of protein leaking into the urine, rising blood pressure with hypertension and then falling renal function is common to many forms of CKD. Protein loss in the urine due to damage of the glomeruli may become massive, and cause a low serum albumin with resulting generalized body swelling (edema) so called nephrotic syndrome. Likewise, the estimated glomerular filtration rate (eGFR) may progressively fall from a normal of over 90 ml/min/1.73m2 to less than 15, at which point the patient is said to have end-stage renal disease. It usually is slowly progressive over years.

<span class="mw-page-title-main">Hypertensive kidney disease</span> Medical condition

Hypertensive kidney disease is a medical condition referring to damage to the kidney due to chronic high blood pressure. It manifests as hypertensive nephrosclerosis. It should be distinguished from renovascular hypertension, which is a form of secondary hypertension, and thus has opposite direction of causation.

<span class="mw-page-title-main">Minimal change disease</span> Medical condition

Minimal change disease(MCD), also known as lipoid nephrosis or nil disease, among others, is a disease affecting the kidneys which causes nephrotic syndrome. Nephrotic syndrome leads to the loss of significant amounts of protein in the urine, which causes the widespread edema (soft tissue swelling) and impaired kidney function commonly experienced by those affected by the disease. It is most common in children and has a peak incidence at 2 to 6 years of age. MCD is responsible for 10–25% of nephrotic syndrome cases in adults. It is also the most common cause of nephrotic syndrome of unclear cause (idiopathic) in children.

<span class="mw-page-title-main">Nephritic syndrome</span> Medical condition

Nephritic syndrome is a syndrome comprising signs of nephritis, which is kidney disease involving inflammation. It often occurs in the glomerulus, where it is called glomerulonephritis. Glomerulonephritis is characterized by inflammation and thinning of the glomerular basement membrane and the occurrence of small pores in the podocytes of the glomerulus. These pores become large enough to permit both proteins and red blood cells to pass into the urine. By contrast, nephrotic syndrome is characterized by proteinuria and a constellation of other symptoms that specifically do not include hematuria. Nephritic syndrome, like nephrotic syndrome, may involve low level of albumin in the blood due to the protein albumin moving from the blood to the urine.

<span class="mw-page-title-main">Focal segmental glomerulosclerosis</span> Kidney disease

Focal segmental glomerulosclerosis (FSGS) is a histopathologic finding of scarring (sclerosis) of glomeruli and damage to renal podocytes. This process damages the filtration function of the kidney, resulting in protein presence in the urine due to protein loss. FSGS is a leading cause of excess protein loss—nephrotic syndrome—in children and adults. Signs and symptoms include proteinuria and edema. Kidney failure is a common long-term complication of the disease. FSGS can be classified as primary, secondary, or genetic, depending on whether a particular toxic or pathologic stressor or genetic predisposition can be identified as the cause. Diagnosis is established by renal biopsy, and treatment consists of glucocorticoids and other immune-modulatory drugs. Response to therapy is variable, with a significant portion of patients progressing to end-stage kidney failure. An American epidemiological study 20 years ago demonstrated that FSGS is estimated to occur in 7 persons per million, with males and African-Americans at higher risk.

Microalbuminuria is a term to describe a moderate increase in the level of urine albumin. It occurs when the kidney leaks small amounts of albumin into the urine, in other words, when an abnormally high permeability for albumin in the glomerulus of the kidney occurs. Normally, the kidneys filter albumin, so if albumin is found in the urine, then it is a marker of kidney disease. The term microalbuminuria is now discouraged by Kidney Disease Improving Global Outcomes and has been replaced by moderately increased albuminuria.

<span class="mw-page-title-main">Renal vein thrombosis</span> Medical condition

Renal vein thrombosis (RVT) is the formation of a clot in the vein that drains blood from the kidneys, ultimately leading to a reduction in the drainage of one or both kidneys and the possible migration of the clot to other parts of the body. First described by German pathologist Friedrich Daniel von Recklinghausen in 1861, RVT most commonly affects two subpopulations: newly born infants with blood clotting abnormalities or dehydration and adults with nephrotic syndrome.

<span class="mw-page-title-main">Hypoalbuminemia</span> Medical condition

Hypoalbuminemia is a medical sign in which the level of albumin in the blood is low. This can be due to decreased production in the liver, increased loss in the gastrointestinal tract or kidneys, increased use in the body, or abnormal distribution between body compartments. Patients often present with hypoalbuminemia as a result of another disease process such as malnutrition as a result of severe anorexia nervosa, sepsis, cirrhosis in the liver, nephrotic syndrome in the kidneys, or protein-losing enteropathy in the gastrointestinal tract. One of the roles of albumin is being the major driver of oncotic pressure in the bloodstream and the body. Thus, hypoalbuminemia leads to abnormal distributions of fluids within the body and its compartments. As a result, associated symptoms include edema in the lower legs, ascites in the abdomen, and effusions around internal organs. Laboratory tests aimed at assessing liver function diagnose hypoalbuminemia. Once identified, it is a poor prognostic indicator for patients with a variety of different diseases. Yet, it is only treated in very specific indications in patients with cirrhosis and nephrotic syndrome. Treatment instead focuses on the underlying cause of the hypoalbuminemia. Albumin is an acute negative phase respondent and not a reliable indicator of nutrition status.

Congenital nephrotic syndrome is a rare kidney disease which manifests in infants during the first 3 months of life, and is characterized by high levels of protein in the urine (proteinuria), low levels of protein in the blood, and swelling. This disease is primarily caused by genetic mutations which result in damage to components of the glomerular filtration barrier and allow for leakage of plasma proteins into the urinary space.

<span class="mw-page-title-main">Atrasentan</span> Chemical compound

Atrasentan is an experimental drug that is being studied for the treatment of various types of cancer, including non-small cell lung cancer. It is also being investigated as a therapy for diabetic kidney disease.

Glomerulonephrosis is a non-inflammatory disease of the kidney (nephrosis) presenting primarily in the glomerulus as nephrotic syndrome. The nephron is the functional unit of the kidney and it contains the glomerulus, which acts as a filter for blood to retain proteins and blood lipids. Damage to these filtration units results in important blood contents being released as waste in urine. This disease can be characterized by symptoms such as fatigue, swelling, and foamy urine, and can lead to chronic kidney disease and ultimately end-stage renal disease, as well as cardiovascular diseases. Glomerulonephrosis can present as either primary glomerulonephrosis or secondary glomerulonephrosis.

<span class="mw-page-title-main">Urine test strip</span> Diagnostic tool used in urinalysis

A urine test strip or dipstick is a basic diagnostic tool used to determine pathological changes in a patient's urine in standard urinalysis.

Sickle cell nephropathy is a type of nephropathy associated with sickle cell disease which causes kidney complications as a result of sickling of red blood cells in the small blood vessels. The hypertonic and relatively hypoxic environment of the renal medulla, coupled with the slow blood flow in the vasa recta, favors sickling of red blood cells, with resultant local infarction. Functional tubule defects in patients with sickle cell disease are likely the result of partial ischemic injury to the renal tubules.

References

  1. 1 2 3 4 Eknoyan G, Lameire N, Eckardt K, Kasiske B, Wheeler D, Levin A, et al. (January 2013). "KDIGO 2012 clinical practice guideline for the evaluation and management of chronic kidney disease" (PDF). Kidney International Supplements. 3 (1): 136–150. Archived from the original (PDF) on 4 March 2016.
  2. Vivian EM (2009). "Endocrine Disorders". In Lee M (ed.). Basic Skills in Interpreting Laboratory Data (fourth ed.). Bethesda, Maryland: American Society of Health-System Pharmacists. pp. 271–318 (291). ISBN   978-1-58528-274-6.
  3. "Person—microalbumin level (measured)". Australian Institute of Health and Welfare. 1 March 2005.
  4. Justesen TI, Petersen JL, Ekbom P, Damm P, Mathiesen ER (April 2006). "Albumin-to-creatinine ratio in random urine samples might replace 24-h urine collections in screening for micro- and macroalbuminuria in pregnant woman with type 1 diabetes". Diabetes Care. 29 (4): 924–925. doi: 10.2337/diacare.29.04.06.dc06-1555 . PMID   16567839.
  5. de Mello VD, Zelmanovitz T, Perassolo MS, Azevedo MJ, Gross JL (May 2006). "Withdrawal of red meat from the usual diet reduces albuminuria and improves serum fatty acid profile in type 2 diabetes patients with macroalbuminuria". The American Journal of Clinical Nutrition. 83 (5): 1032–8. doi: 10.1093/ajcn/83.5.1032 . PMID   16685043.
  6. Pan Y, Guo LL, Jin HM (September 2008). "Low-protein diet for diabetic nephropathy: a meta-analysis of randomized controlled trials". The American Journal of Clinical Nutrition. 88 (3): 660–6. doi: 10.1093/ajcn/88.3.660 . PMID   18779281.