Tag Archives: Albumin

Diabetes: ‘Gold Standard’ HbA1c Test Not So Great For Dialysis Patients ‎

In situations where rapid changes occur in blood sugar, the glycated albumin (GA) test gives a more accurate picture of diabetes control

BLOOD sugar monitoring is a vital part of diabetes management. Patients and physicians rely on the hemoglobin A1c (HbA1c) test to measure an individual’s average blood sugar level over the prior three months. It is the most commonly used long-term blood sugar test, and the gold standard for the medical community.

While the American Diabetes Association has deemed the HbA1c test an effective tool for diagnosing diabetes, kidney doctors recently determined that the HbA1c is not as useful for managing patients with diabetes and advanced kidney failure. Another test, the glycated albumin or GA assay, appears to be far more effective in this setting, they say.

The GA test, developed by Tokyo-based Asahi Kasei Pharma Corporation, measures blood sugars over the past 17 days, as opposed to the longer time frame for HbA1c. In situations where rapid changes occur in blood sugar, the GA gives a more accurate picture of diabetes control. The GA test used in this study is available in Japan, China and South Korea, but is not yet FDA approved in the United States.

According to a new study at Wake Forest Baptist Medical Center, which appears online in the Clinical Journal of the American Society of Nephrology and is scheduled for the July print issue, many organs don’t function properly in severe kidney failure. For example, most dialysis patients have anemia with fewer red blood cells than they should, which has a dramatic impact on the accuracy of the HbA1c reading.

Hemoglobin inside red blood cells carries oxygen in the body. Blood sugar chemically interacts with the hemoglobin to identify a value for HbA1c. But HbA1c results are only accurate when red cells have a normal lifespan. Dialysis patients have shorter red cell survival, reducing the time that sugar in the bloodstream has to interact with hemoglobin, and causing lower HbA1c values.

“Doctors long thought the HbA1c predicted outcomes in diabetes. This test is not predictive of outcomes in diabetes patients with kidney disease on dialysis. Dialysis patients and physicians get a false sense of security because their lower HbA1c actually relates to shorter red cell survival, yet suggests diabetes control is better than it really is,” explained Barry I. Freedman, M.D., John H. Felts III Professor and lead investigator.

“This is the first study showing that a blood sugar test predicts risk of death in diabetic dialysis patients, as well as risk of hospitalization,” Freedman said. “This test provides the missing link that will allow dialysis patients and physicians to accurately gauge risk. The association is clear: high GA readings predict higher risk.”

Freedman and colleagues evaluated 444 patients with diabetes undergoing dialysis. Patients continued their normal treatment and HbA1c monitoring, but also agreed to have a GA test every three months for an average of more than 2.3 years.

Wake Forest Baptist researchers compared the patients’ HbA1c and GA test results, assessing their ability to predict hospitalizations and survival. They found that the HbA1c failed to predict these important medical outcomes. In contrast, the GA was a strong predictor of patient survival and hospitalizations.

Nearly 500,000 people are on dialysis in the Unites States and diabetes is the cause of kidney failure in nearly 50 percent of them. Diabetes is the most common cause of kidney failure worldwide and is associated with high mortality rates – more than 20 percent of dialysis patients die each year. As such, there is an urgent need for accurate blood sugar testing in diabetic dialysis patients.

Freedman suggests physicians not rely on the HbA1c in dialysis patients, instead suggesting that blood glucose levels be directly monitored with multiple daily readings until the GA test is available in the states.

The GA test is not limited only to dialysis patients. Some studies have shown that shorter-term markers for glucose control may lead to better management of glucose than longer-term measures with the HbA1c test. So, instead of waiting 3-6 months for an HbA1c test, which is the current recommendation, the rapid and inexpensive GA test could be performed monthly.

Several studies have confirmed that measurements of GA and HbA1c are closely correlated. Though the GA test has been available in labs for years, Epinex Diagnostics, the developer of the rapid result GA measurement called G1A™, believes the mounting scientific evidence that supports GA testing will eventually gain wide acceptance among professionals. Numerous studies show the need for a mid-range test that could be performed monthly as another means of helping people with diabetes manage their glucose levels more effectively.

Sources: Wake Forest Baptist Medical Center, Epinex Diagnostics

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Diabetes: Understanding Proteinuria

Proteinuria—also called albuminuria or urine albumin—is a condition in which urine contains an abnormal amount of protein. Albumin is the main protein in the blood. Proteins are the building blocks for all body parts, including muscles, bones, hair, and nails.

Proteins in the blood also perform a number of important functions. They protect the body from infection, help blood clot, and keep the right amount of fluid circulating throughout the body.

As blood passes through healthy kidneys, they filter out the waste products and leave in the things the body needs, like albumin and other proteins. Most proteins are too big to pass through the kidneys’ filters into the urine. However, proteins from the blood can leak into the urine when the filters of the kidney, called glomeruli, are damaged.

Proteinuria is a sign of chronic kidney disease (CKD), which can result from diabetes, high blood pressure, and diseases that cause inflammation in the kidneys. For this reason, testing for albumin in the urine is part of a routine medical assessment for everyone. Kidney disease is sometimes called renal disease.

If CKD progresses, it can lead to end-stage renal disease (ESRD), when the kidneys fail completely. A person with ESRD must receive a kidney transplant or regular blood-cleansing treatments called dialysis.

Who is at risk for proteinuria?
People with diabetes, hypertension, or certain family backgrounds are at risk for proteinuria. Indeed, diabetes is the leading cause of ESRD. In both type 1 and type 2 diabetes, albumin in the urine is one of the first signs of deteriorating kidney function. As kidney function declines, the amount of albumin in the urine increases.

Another risk factor for developing proteinuria is hypertension, or high blood pressure. Proteinuria in a person with high blood pressure is an indicator of declining kidney function. If the hypertension is not controlled, the person can progress to full kidney failure.

What are the signs and symptoms of proteinuria?
Proteinuria has no signs or symptoms in the early stages. Large amounts of protein in the urine may cause it to look foamy in the toilet. Also, because protein has left the body, the blood can no longer soak up enough fluid, so swelling in the hands, feet, abdomen, or face may occur. This swelling is called edema. These are signs of large protein loss and indicate that kidney disease has progressed. Laboratory testing is the only way to find out whether protein is in a person’s urine before extensive kidney damage occurs.

Several health organizations recommend regular urine checks for people at risk for CKD. A 1996 study sponsored by the US National Institutes of Health determined that proteinuria is the best predictor of progressive kidney failure in people with type 2 diabetes. The American Diabetes Association recommends regular urine testing for proteinuria for people with type 1 or type 2 diabetes. The National Kidney Foundation recommends that routine checkups include testing for excess protein in the urine, especially for people in high-risk groups.

What are the tests for proteinuria?
Until recently, an accurate protein measurement required a 24-hour urine collection. In a 24-hour collection, the patient urinates into a container, which is kept refrigerated between trips to the bathroom. The patient is instructed to begin collecting urine after the first trip to the bathroom in the morning. Every drop of urine for the rest of the day is to be collected in the container. The next morning, the patient adds the first urination after waking and the collection is complete.

In recent years, researchers have found that a single urine sample can provide the needed information. In the newer technique, the amount of albumin in the urine sample is compared with the amount of creatinine, a waste product of normal muscle breakdown. The measurement is called a urine albumin-to-creatinine ratio (UACR).

A urine sample containing more than 30 milligrams of albumin for each gram of creatinine (30 mg/g) is a warning that there may be a problem. If the laboratory test exceeds 30 mg/g, another UACR test should be done 1 to 2 weeks later. If the second test also shows high levels of protein, the person has persistent proteinuria, a sign of declining kidney function, and should have additional tests to evaluate kidney function.

What additional tests for kidney disease may be needed?
Tests that measure the amount of creatinine in the blood will show whether a person’s kidneys are removing wastes efficiently. Having too much creatinine in the blood is a sign that a person has kidney damage. The doctor can use the creatinine measurement to estimate how efficiently the kidneys are filtering the blood. This calculation is called the estimated glomerular filtration rate, or eGFR. CKD is present when the eGFR is less than 60 milliliters per minute (mL/min).

What should a person with proteinuria do?
If a person has diabetes, hypertension, or both, the first goal of treatment will be to control blood glucose, also called blood sugar, and blood pressure. People with diabetes should test their blood glucose often, follow a healthy eating plan, take prescribed medicines, and get the amount of exercise recommended by their doctor.

A person with diabetes and high blood pressure may need a medicine from a class of drugs called angiotensin-converting enzyme (ACE) inhibitors or a similar class called angiotensin receptor blockers (ARBs). These drugs have been found to protect kidney function even more than other drugs that provide the same level of blood pressure control. Many patients with proteinuria but without hypertension may also benefit from ACE inhibitors or ARBs. The American Diabetes Association and the American College of Cardiology recommend that people with diabetes keep their blood pressure below 130/80.

People who have high blood pressure and proteinuria, but not diabetes, also benefit from taking an ACE inhibitor or ARB. The Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends that people with kidney disease keep their blood pressure below 130/80. To maintain this target, a person may need to take a combination of two or more blood pressure medicines. A doctor may also prescribe a diuretic in addition to an ACE inhibitor or ARB. Diuretics are also called “water pills” because they help a person urinate and get rid of excess fluid in the body.

In addition to blood glucose and blood pressure control, the National Kidney Foundation recommends restricting dietary salt and protein. A doctor may refer a patient to a dietitian to help develop and follow a healthy eating plan.

Points to Remember
Proteinuria is a condition in which urine contains a detectable amount of protein.

Proteinuria is a sign of chronic kidney disease (CKD).

Groups at risk for proteinuria include people with diabetes or hypertension, and people who have a family history of kidney disease.

Proteinuria may have no signs or symptoms. Laboratory testing is the only way to find out whether protein is in a person’s urine.

Several health organizations recommend regular checks for proteinuria so kidney disease can be detected and treated before it progresses.
A person with diabetes, hypertension, or both should work to control blood glucose and blood pressure.

Source: National Kidney & Urologic Diseases Information Clearinghouse (NKUDIC)

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