Microalbuminuria

Microalbumin in clinical diagnosis

1. Billroth Laboratory Microalbuminuria Dr. K. Selvakumar

2. Microalbuminuria Other Name: Urine Albumin and Albumin/Creatinine Ratio WHY GET TESTED? To detect early kidney disease in those with diabetes or other risk factors, such as high blood pressure (hypertension) WHEN TO GET TESTED? Annually after a diagnosis of type 2 diabetes; annually 5 years after diagnosis of type 1 diabetes

3. SAMPLE REQUIRED? A random, Spot, overnight, or 24-hour urine sample TEST PREPARATION NEEDED? None

4. Albumin is a major protein normally present in blood. The urine albumin test detects and measures the amount of albumin in the urine. The presence of a small amount of albumin in the urine may be an early indicator of kidney disease. A small amount of albumin in the urine is sometimes referred to as URINE MICROALBUMIN OR MICROALBUMINURIA. " Microalbuminuria" is slowly being replaced with the term "albuminuria," which refers to any elevation of albumin in the urine. Protein in the urine (proteinuria) most often occurs when either the glomeruli or tubules in the kidney are damaged. Inflammation and/or scarring of the glomeruli can allow increasing amounts of protein to leak into the urine. Damage to the tubules can prevent protein from being reabsorbed . WHAT IS BEING TESTED?

5. Albumin is one of the first proteins to be detected in the urine with kidney damage. People who have consistently detectable small amounts of albumin in their urine ( albuminuria ) have an increased risk of developing progressive kidney failure and cardiovascular disease in the future. A urine albumin test is used to screen for kidney disease in people with chronic conditions such as diabetes and high blood pressure. It can detect small amounts of albumin that escape from the blood through the kidneys into the urine several years before significant kidney damage becomes apparent.

6. Most of the time, both albumin and creatinine are measured in a random urine sample and an albumin/ creatinine ratio (ACR) is calculated. This may be done to more accurately determine how much albumin is escaping from the kidneys into the urine. The concentration (or dilution) of urine varies throughout the day with more or less liquid being released in addition to the body's waste products. Thus, the concentration of albumin in the urine may also vary.

7. Creatinine, a byproduct of muscle metabolism , is normally released into the urine at a constant rate and its level in the urine is an indication of the urine concentration. This property of creatinine allows its measurement to be used to correct for urine concentration in a random urine sample. The American Diabetes Association has stated a preference for the ACR for screening for albuminuria indicating early kidney disease. Since the amount of albumin in the urine can vary considerably, an elevated ACR should be repeated twice within 3 to 6 months to confirm the diagnosis.

8. Plasma , the liquid portion of blood, contains many different proteins, including albumin. One of the many functions of the kidneys is to conserve plasma proteins so that they are not released along with waste products when urine is produced. There are two mechanisms that normally prevent protein from passing into urine: (1) the glomeruli provide a barrier that keeps most large plasma proteins inside the blood vessels and (2) the smaller proteins that do get through are almost entirely reabsorbed by the tubules. THE TEST SAMPLE : WHAT IS BEING TESTED?

9. Albumin is a globular, water-soluble, un-glycosylated serum protein of approximate molecular weight of 65,000 Daltons . (10 -24 ) Albumin (when ionized in water at pH 7.4, as found in the body) is negatively charged. The glomerular basement membrane is also negatively charged in the body; some studies suggest that this prevents the filtration of albumin in the urine. According to this theory, that charge plays a major role in the selective exclusion of albumin from the glomerular filtrate. A defect in this property results in nephrotic syndrome leading to albumin loss in the urine. Nephrotic syndrome patients are sometimes given albumin to replace the lost albumin . It constitutes about half of serum protein. It is produced in the liver.

10. Maintains oncotic pressure (Prevents water enter in to circulatory system) Transports thyroid hormones & other hormones, in particular, ones that are fat-soluble Transports fatty acids ("free" fatty acids) to the liver and to myocytes for utilization of energy Transports unconjugated  bilirubin Transports many drugs; serum albumin levels can affect the half-life of drugs Competitively binds calcium ions (Ca 2+ ) Serum albumin, as a negative acute-phase protein, is down-regulated in inflammatory states. As such, it is not a valid marker of nutritional status; rather, it is a marker of an inflammatory state Prevents photodegradation of folic acid FUNCTIONS

11. 800,000 to 1.5 million  nephrons

12. Difference between serum/plasma albumin, prealbumin , and urine albumin Although the names are similar,  albumin and  prealbumin  are completely different molecules. They are both proteins made by the liver, however, and both have been used historically to evaluate nutritional status. Serum/plasma (or blood) albumin is now more often used to screen for and help diagnose liver or kidney disease and is tested on a blood sample. The urine albumin test (also called a microalbumin test) detects and measures albumin in the urine as an early indicator of kidney damage.

13. MOLECULAR MECHANISM BEHIND THE MICROVASCULAR DYSFUNCTION

14. I CAN DO TO PREVENT MICROALBUMINURIA? Yes, if you are diabetic, control over your blood glucose level. Keeping high blood pressure under control is also effective in preventing kidney damage that leads to microalbuminuria . Some studies have shown that those who have albuminuria can prevent it from worsening or may reverse it with good glycemic and blood pressure control, or by quitting smoking.

15. OTHER CAUSES Yes, albuminuria is not specific for diabetes. It may also be associated with  hypertension (high blood pressure), some lipid abnormalities, and several immune disorders. Elevated results may also be caused by vigorous exercise, blood in the urine, urinary tract infection, dehydration, and some drugs.

16. Normal Value : 50371877

17. Albumin / Creatinine Ratio Urine Albumin (µ-alb) & Urine Creatinine Protein / Creatinine Ratio Urine Protein & Urine Creatinine Urine Protein Manual Machine Nil <35 µg/dl + 100 ++ 200 +++ 500 ++++ >1000

18. eGFR EPE X 0.85 MALE FEMALE