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In this Issue...
Increasing Awareness of Urine Albumin Testing:
Health Officials Call for More Widespread Testing, Especially Among Diabetic Patients
The most common cause of end-stage renal disease (ESRD) is type 2 diabetes, prompting health officials to push for early detection by testing for kidney disease markers such as the level of albumin in urine. All type I and type II diabetic patients covered under all health plans are supposed to be tested for microalbuminuria once a year, and many medical associations, including the National Kidney Foundation and the American Diabetes Association, recommend annual testing for these patients. However, research suggests that many primary care physicians do not routinely order microalbumin tests for their diabetic patients. This issue of Strategies examines some reasons for this noncompliance and the clinical laboratory’s role in improving awareness of the importance of this test.
Chronic kidney disease (CKD) can exist for many years before progressing to ESRD and if detected early enough, the disease can be slowed and even stabilized. But many detection techniques fail to identify mild to moderate reduction in glomerular filtration rate (GFR)—an indicator of kidney damage. But albumin has proven to be a good marker for both CKD and cardiovascular disease, since abnormalities in urinary albumin are present several years before significant decline in kidney function becomes apparent and cardiovascular disease progresses into advanced stages. Because diabetes is the leading cause of ESRD and two-thirds to three-fourths of diabetic patients die of cardiovascular disease, many evidence-based guidelines recommend annual microalbuminuria testing. However, in 2004, only 52% of diabetic patients covered by commercial health insurance plans were tested for microalbuminuria, while 91% had their lipid profile evaluated and 86.5% were tested for HbA1c, according to the National Committee for Quality Assurance’s (NCQA) State of Health Care Quality 2005 report. The compliance is lower for Medicaid patients—in 2004, only 46.7% of diabetic patients were tested for microalbuminuria, while 79.6% had their lipid profile done and 76% had their HbA1c levels tested. The NCQA’s Comprehensive Diabetes Care measures recommend that all three tests be performed once a year.
What are some of the reasons for these low testing rates? “It’s a question of awareness more than anything else,” said Derek LeRoith, MD, PhD, Chief of the Division of Endocrinology and Diabetes, Department of Medicine, Mt.Sinai School of Medicine in New York City. “Primary care physicians are very aware of measuring blood pressure, lipids, and blood sugar in the blood stream, so they order these tests routinely, usually around once a year or more if it’s a diabetic patient. They are less aware of the importance of microalbuminuria testing, even though it’s very important for diabetic patients. It’s sort of been sidelined to leave it to the specialists, like nephrologists, but really it should be in the realm of the primary care physician who is seeing most of our diabetic patients.”
The test has also gained even more attention with the recent release of the American Heart Association’s Science Advisory, “Detection of Chronic Kidney Disease in Patients With or at Increased Risk of Cardiovascular Disease,” which was published in Circulation (2006;114;1083–1087).
The recommendations include two tests to detect kidney disease: a test for estimated GFR using the Modification of Diet in Renal Disease (MDRD) equation and a test for microalbuminuria. The abbreviated MDRD study equation for calculating GFR is GFR = 186 x [SCr]-1.154 x [age]-0.203 x [0.742 if patient is female] x [1.21 if patient is black]. SCr indicates serum creatinine. For the estimated GFR test, abnormal results are <60 mL/minute; in the microalbuminuria test, abnormal results are >30 mg albumin/g creatinine. If either of these two tests results is positive, the test should be repeated at 3 months. If it is still positive, the patient should be considered to have CKD, and advised of appropriate treatment options. If the results are negative, the test should be repeated annually and patients with extremely low GFR or high urinary albumin-to-creatinine ratios should be referred to a nephrologist.
These recommendations are important because of the link between CKD and cardiovascular disease, and the implicit role that laboratory evaluation plays in evaluating the risk and progression of these diseases. “Physicians should evaluate chronic kidney disease patients for cardiovascular disease and the other way around—people with cardiovascular disease should be tested for chronic kidney disease,” explained Joseph Vassalotti, MD, Chief Medical Officer at the National Kidney Foundation. “So anyone with cardiovascular disease should be tested as well.”
Improving Lab Reporting
One possibility to improve awareness of microalbumin testing is standardizing how labs report the results. Currently, the Laboratory Working Group of the National Kidney Disease Education Program (NKDEP) is working on standardizing lab reporting of serum creatinine levels and estimated GFR nationwide. NKDEP is an initiative of the National Institutes of Health focused on reducing the morbidity and mortality caused by kidney disease and related complications.
“Currently, there is no consistency in how the urine albumin test is reported,” said Vassalotti. “What is confusing to practitioners is the interpretation of the results. For example, a lab may report both the concentration of urinary albumin and creatinine in different units without the ratio. What the clinicians need is a uniform reporting format of the ratio, preferably in the same units, such as mg albumin per g creatinine.”
Perhaps the NKDEP will lead this effort for the clinical laboratories, because of their current efforts and success in standardizing the reporting of serum creatinine and estimated GFR nationwide. This group might also standardize the urine albumin-creatinine ratio results in a uniform reporting format, as well as indicate the three levels of the urine-creatine ratio—normal level, microalbumiuria, and macroalbuminuria—on the lab report. “It would be ideal if the criteria for those were on the lab report,” said Vassalotti. “It would facilitate recognition among primary care physicians.”
For more information:
The August 31 issue, “More Newborn Screening Tests, More False Positives”, indicated that only the District of Columbia, Iowa, Maryland, Mississippi, New Jersey, and Virginia require that newborns be screened for the full panel of 29 disorders, as recommended by the American College of Medical Genetics, the March of Dimes, and the American Academy of Pediatrics. However, since Utah has been screening for 36 disorders since early 2005, it should be added to that list, as well as Alaska and Hawaii. According the map reprinted from the Pediatrics article—“Increase in newborn screening panels by state, 1995-2005”—Alaska has added 34 disorders to their screening panel and Hawaii has added 38 disorders.