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 there is an abnormally high permeability for albumin in the glomerulus of the kidney. Normally the kidneys filter albumin, so if albumin is found in the urine it's then a marker of kidney disease. The term 'microalbuminuria' is now discouraged by KDIGO (Kidney Disease Improving Global Outcomes) and has been replaced by 'moderately increased albuminuria'.
Video Microalbuminuria
Associations/Indications
- 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 pre-diabetes. Pre-diabetes 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.
Maps Microalbuminuria
Causes/Prevention
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.
Diagnosis
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 30-300 mg/24 hours) or, more commonly, from elevated concentration in a spot sample (20 to 200 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.
To compensate for variations in urine concentration in spot-check samples, it is helpful to compare the amount of albumin in the sample against its concentration of creatinine. 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 too much or too little muscle mass. This is due to the variation in creatinine level which is produced by the muscle.
See also
- Albuminuria
References
- Abid O, Sun Q, Sugimoto K, Mercan D, Vincent JL (2001). "Predictive value of microalbuminuria in medical ICU patients: results of a pilot study". Chest. 120 (6): 1984-8. doi:10.1378/chest.120.6.1984. PMID 11742932.
- Andersen S, Blouch K, Bialek J, Deckert M, Parving HH, Myers BD (2000). "Glomerular permselectivity in early stages of overt diabetic nephropathy". Kidney Int. 58 (5): 2129-37. doi:10.1111/j.1523-1755.2000.00386.x. PMID 11044234.
- Heart Outcomes Prevention Evaluation Study Investigators (2000). "Effects of ramipril on cardiovascular and microvascular outcomes in people with diabetes mellitus: results of the HOPE study and MICRO-HOPE substudy". Lancet. 355 (9200): 253-9. doi:10.1016/S0140-6736(99)12323-7. PMID 10675071.
- Lemley KV, Abdullah I, Myers BD, et al. (2000). "Evolution of incipient nephropathy in type 2 diabetes mellitus". Kidney Int. 58 (3): 1228-37. doi:10.1046/j.1523-1755.2000.00223.x. PMID 10972685.
- Lièvre M, Marre M, Chatellier G, et al. (2000). "The non-insulin-dependent diabetes, hypertension, microalbuminuria or proteinuria, cardiovascular events, and ramipril (DIABHYCAR) study: design, organization, and patient recruitment. DIABHYCAR Study Group". Controlled Clinical Trials. 21 (4): 383-96. doi:10.1016/S0197-2456(00)00060-X. PMID 10913814.
- Parving HH, Lehnert H, Bröchner-Mortensen J, Gomis R, Andersen S, Arner P (2001). "The effect of irbesartan on the development of diabetic nephropathy in patients with type 2 diabetes". N. Engl. J. Med. 345 (12): 870-8. doi:10.1056/NEJMoa011489. PMID 11565519.
- 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
External links
- Microalbumin and Urine Albumin/Creatinine Ratio - Lab Tests Online
Source of the article : Wikipedia