Microalbuminuria

Causes

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

Associations

• Marker of vascular endothelial dysfunction
• An important prognostic marker for kidney disease
  • in diabetes mellitus
  • in hypertension
  • in post-streptococcal glomerulonephritis
• Increasing microalbuminuria during the first 48 hours after admission to an intensive care unit predicts elevated risk for acute respiratory failure, multiple organ failure, and overall mortality
• A risk factor for venous thromboembolism

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.

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.

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.

albumin/creatinine ratio

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) and microalbuminuria is defined as ACR ≥3.5 mg/mmol (female) or ≥2.5 mg/mmol (male), or with both substances measured by mass, as an ACR between 30 and 300 μg albumin/mg creatinine. 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.

• Albuminuria --

References

• Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney inter., Suppl. 2013; 3: 1–150.

Footnotes

References

1. "KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease".
2. (2010-05-01). "Associations of diet with albuminuria and kidney function decline". Clinical Journal of the American Society of Nephrology.
3. (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.
4. (1987-01-01). "Dietary composition and renal function in healthy subjects". Nephron.
5. (1996-01-01). "A low-nitrogen low-phosphorus Vegan diet for patients with chronic renal failure". Nephron.
6. (2009). "Microalbuminuria and risk of venous thromboembolism". JAMA: The Journal of the American Medical Association.
7. (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.
8. "Person—microalbumin level (measured), total micrograms per minute N[NNN].N".
9. Bakker AJ. (February 1999). "Detection of microalbuminuria. Receiver operating characteristic curve analysis favors albumin-to-creatinine ratio over albumin concentration". Diabetes Care.
10. (December 15, 2005). "Proteinuria". UK Renal Association.
11. [http://www.clinlabnavigator.com/index.php?option=com_content&view=article&id=412:microalbumin&catid=35:test-interpretations clinlabnavigator.com > Test Interpretations] Last Updated on Saturday, 19 June 2010
12. [http://www.treatmentandsymptoms.com/renal-nephrology/microalbuminuria-in-type-2-diabetes-mellitus/ Microalbuminura in diabetes]
13. Mary Lee. (2009-02-26). "Basic Skills in Interpreting Laboratory Data". ASHP.
14. [http://meteor.aihw.gov.au/content/index.phtml/itemId/270339 Person—microalbumin level (measured)] at Australian Institute of Health and Welfare. 01/03/2005
15. (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.