Microalbuminuria

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Microalbuminuria
Specialty Nephrology

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 The term microalbuminuria is now discouraged by Kidney Disease Improving Global Outcomes [1] and has been replaced by moderately increased albuminuria.

Contents

Causes

Higher dietary intake of animal protein, animal fat, and cholesterol may increase risk for microalbuminuria, [2] and generally, diets higher in fruits, vegetables, and whole grains but lower in meat and sweets may be protective against kidney function decline. [3] [4] [5]

Associations

Microalbuminuria is an important adverse predictor of glycemic outcomes in prediabetes. Prediabetes individuals with increased microalbuminuria even in the so-called normal range is associated with increased progression to diabetes and decreased reversal to normoglycemia. Hence, prediabetes individuals with microalbuminuria warrant more aggressive intervention to prevent diabetes in them. [7]

Diagnosis and treatment

The level of albumin protein produced by microalbuminuria can be detected by special albumin-specific urine dipsticks, which have a lower detection threshold than standard urine dipsticks. A microalbumin urine test determines the presence of the albumin in urine. In a properly functioning body, albumin is not normally present in urine because it is retained in the bloodstream by the kidneys.

Microalbuminuria can be diagnosed from a 24-hour urine collection (between 30 and 300 mg/24 hours) or, more commonly, from elevated concentration in a spot sample (30 to 300 mg/L). Both must be measured on at least two of three measurements over a two- to three-month period. [8]

An albumin level above the upper limit values is called "macroalbuminuria", or sometimes just albuminuria. Sometimes, the upper limit value is given as one less (such as 300 being given as 299) to mark that the higher value (here 300) is defined as macroalbuminuria. [9]

Taurine in combination with N-acetylcysteine (Nefrosave Tablet) was useful in attenuating UACR in microalbuminuric type 2 diabetic patient as per Indian Journal of Nephrology 2008

To compensate for variations in urine concentration in spot-check samples, comparing the amount of albumin in the sample against its concentration of creatinine is helpful. This is termed the albumin/creatinine ratio (ACR) [10] and microalbuminuria is defined as ACR ≥3.5 mg/mmol (female) or ≥2.5 mg/mmol (male), [11] or with both substances measured by mass, as an ACR between 30 and 300 µg albumin/mg creatinine. [12] For the diagnosis of microalbuminuria, care must be taken when collecting sample for the urine ACR. An early-morning sample is preferred. The patient should refrain from heavy exercises 24 hours before the test. A repeat test should be done 3 to 6 months after the first positive test for microalbuminuria. Lastly, the test is inaccurate in a person with very high or very low muscle mass. This is due to the variation in creatinine level which is produced by the muscle. [13]

Definitions of microalbuminuria
IndividualLower limitUpper limitUnit
24h urine collection30 [9] 300 [9] mg/24h (milligram albumin per 24 hours)
Short-time urine collection20 [9] 200 [9] µg/min (microgram albumin per minute)
Spot urine albumin sample30 [14] 300 [14] mg/L (milligram albumin per liter of urine)
Spot urine albumin/creatinine ratioWomen3.5 [15] 25 [15] or 35 [15] mg/mmol (milligram albumin per millimole creatinine)
30 [15] 400 [15] μg/mg (microgram albumin per milligram creatinine)
Men2.5 [15] or 3.5 [15] 25 [15] or 35 [15] mg/mmol
30 [15] 300 [15] μg/mg


Related Research Articles

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 ; 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.

<span class="mw-page-title-main">Creatinine</span> Breakdown product of creatine phosphate

Creatinine is a breakdown product of creatine phosphate from muscle and protein metabolism. It is released at a constant rate by the body.

<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> Collection of symptoms due to kidney damage

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 kidney disease, 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, hyperkalaemia, and volume overload. Complications of chronic failure also include heart disease, high blood pressure, and anaemia.

<span class="mw-page-title-main">Glomerular filtration rate</span> Renal function test

Renal functions include maintaining an acid–base balance; regulating fluid balance; regulating sodium, potassium, and other electrolytes; clearing toxins; absorption of glucose, amino acids, and other small molecules; regulation of blood pressure; production of various hormones, such as erythropoietin; and activation of vitamin D.

<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">Acute kidney injury</span> Medical condition

Acute kidney injury (AKI), previously called acute renal failure (ARF), is a sudden decrease in kidney function that develops within 7 days, as shown by an increase in serum creatinine or a decrease in urine output, or both.

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

Chronic kidney disease (CKD) is a type of kidney disease in which a gradual loss of kidney function occurs over a period of months to years. Initially generally no symptoms are seen, but later symptoms may include leg swelling, feeling tired, vomiting, loss of appetite, and confusion. Complications can relate to hormonal dysfunction of the kidneys and include high blood pressure, bone disease, and anemia. Additionally CKD patients have markedly increased cardiovascular complications with increased risks of death and hospitalization.

<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">Hepatorenal syndrome</span> Human disease

Hepatorenal syndrome is a life-threatening medical condition that consists of rapid deterioration in kidney function in individuals with cirrhosis or fulminant liver failure. HRS is usually fatal unless a liver transplant is performed, although various treatments, such as dialysis, can prevent advancement of the condition.

<span class="mw-page-title-main">Valsartan</span> Angiotensin II receptor antagonist

Valsartan, sold under the brand name Diovan among others, is a medication used to treat high blood pressure, heart failure, and diabetic kidney disease. It belongs to a class of medications referred to as angiotensin II receptor blockers (ARBs). It is a reasonable initial treatment for high blood pressure. It is taken by mouth. Versions are available as the combination valsartan/hydrochlorothiazide, valsartan/amlodipine, valsartan/amlodipine/hydrochlorothiazide, or valsartan/sacubitril.

Contrast-induced nephropathy (CIN) is a purported form of kidney damage in which there has been recent exposure to medical imaging contrast material without another clear cause for the acute kidney injury.

Fructosamines are compounds that result from glycation reactions between a sugar and a primary amine, followed by isomerization via the Amadori rearrangement. Biologically, fructosamines are recognized by fructosamine-3-kinase, which may trigger the degradation of advanced glycation end-products. Fructosamine can also refer to the specific compound 1-amino-1-deoxy-D-fructose (isoglucosamine), first synthesized by Nobel laureate Hermann Emil Fischer in 1886.

Phosphate nephropathy or nephrocalcinosis is an adverse renal condition that arises with a formation of phosphate crystals within the kidney's tubules. This renal insufficiency is associated with the use of oral sodium phosphate (OSP) such as C.B. Fleet's Phospho soda and Salix's Visocol, for bowel cleansing prior to a colonoscopy.   

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.

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

Orthostatic albuminuria, also known as orthostatic proteinuria is defined by raised levels of urine protein excretion while in an upright position. In orthostatic albuminuria urine protein excretion returns to normal while in a supine position, such as laying down. Orthostatic albuminuria is the most common cause of isolated proteinuria in those under 20. The prevalance of orthostatic albuminuria is suspected to be between 2 and 5%, however some studies suggest that it is more common. Orthostatic albuminuria is diagnosed if urine protein levels are normal in a morning urine sample and there are no other obvious causes of albuminuria. Patients with orthostatic albuminuria are often asymptomatic and there is no indication for any type of treatment or interventions.

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

Finerenone, sold under the brand name Kerendia, is a medication used to reduce the risk of kidney function decline, kidney failure, cardiovascular death, non-fatal heart attacks, and hospitalization for heart failure in adults with chronic kidney disease associated with type 2 diabetes. Finerenone is a non-steroidal mineralocorticoid receptor antagonist (MRA). It is taken orally.

References

Footnotes

  1. ↑ "KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease" (PDF).
  2. ↑ Lin, Julie; Hu, Frank B.; Curhan, Gary C. (2010-05-01). "Associations of diet with albuminuria and kidney function decline". Clinical Journal of the American Society of Nephrology. 5 (5): 836–843. doi:10.2215/CJN.08001109. ISSN   1555-905X. PMC   2863979 . PMID   20299364.
  3. ↑ Lin, Julie; Fung, Teresa T.; Hu, Frank B.; Curhan, Gary C. (2011-02-01). "Association of dietary patterns with albuminuria and kidney function decline in older white women: a subgroup analysis from the Nurses' Health Study". American Journal of Kidney Diseases. 57 (2): 245–254. doi:10.1053/j.ajkd.2010.09.027. ISSN   1523-6838. PMC   3026604 . PMID   21251540.
  4. ↑ Wiseman, M. J.; Hunt, R.; Goodwin, A.; Gross, J. L.; Keen, H.; Viberti, G. C. (1987-01-01). "Dietary composition and renal function in healthy subjects". Nephron. 46 (1): 37–42. doi:10.1159/000184293. ISSN   1660-8151. PMID   3600911.
  5. ↑ Barsotti, G.; Morelli, E.; Cupisti, A.; Meola, M.; Dani, L.; Giovannetti, S. (1996-01-01). "A low-nitrogen low-phosphorus Vegan diet for patients with chronic renal failure". Nephron. 74 (2): 390–394. doi:10.1159/000189341. hdl: 11382/374104 . ISSN   1660-8151. PMID   8893161.
  6. ↑ Mahmoodi, BK; Gansevoort, RT; Veeger, NJ; Matthews, AG; Navis, G; Hillege, HL; Van Der Meer, J; Prevention of Renal Vascular End-stage Disease (PREVEND) Study Group (2009). "Microalbuminuria and risk of venous thromboembolism". JAMA: The Journal of the American Medical Association. 301 (17): 1790–7. doi: 10.1001/jama.2009.565 . PMID   19417196.
  7. ↑ Dutta D, Choudhuri S, Mondal SA, Mukherjee S, Chowdhury S (2014). "Urinary albumin : creatinine ratio predicts prediabetes progression to diabetes and reversal to normoglycemia: role of associated insulin resistance, inflammatory cytokines and low vitamin D". Journal of Diabetes. 6 (4): 316–22. doi:10.1111/1753-0407.12112. PMID   24251376. S2CID   206117.
  8. ↑ "Person—microalbumin level (measured), total micrograms per minute N[NNN].N" . Retrieved 2007-07-05.
  9. 1 2 3 4 5 Mary Lee (2009-02-26). Basic Skills in Interpreting Laboratory Data. ASHP. pp. 291–. ISBN   978-1-58528-274-6.
  10. ↑ Bakker AJ (February 1999). "Detection of microalbuminuria. Receiver operating characteristic curve analysis favors albumin-to-creatinine ratio over albumin concentration". Diabetes Care. 22 (2): 307–13. doi:10.2337/diacare.22.2.307. PMID   10333950.
  11. ↑ "Proteinuria". UK Renal Association. December 15, 2005. Archived from the original on August 14, 2007.
  12. ↑ clinlabnavigator.com > Test Interpretations Last Updated on Saturday, 19 June 2010
  13. ↑ Microalbuminura in diabetes
  14. 1 2 Person—microalbumin level (measured) at Australian Institute of Health and Welfare. 01/03/2005
  15. 1 2 3 4 5 6 7 8 9 10 11 Justesen, T.; Petersen, J.; Ekbom, P.; Damm, P.; Mathiesen, E. (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.
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