SAN DIEGO (FRONTLINE MEDICAL NEWS) – Assessing the risk of kidney disease in diabetes requires estimating the glomerular filtration rate.

“One of the big campaigns is Know Your Numbers, and we think of ABC,” also known as hemoglobin A1c, blood pressure, and cholesterol levels, noted Andrew Bzowyckyj, PharmD, BCPS, CDE. “Now we have eGFR, which measures kidney function. It’s something quantifiable that patients can follow.”

Earlier this year, the Food and Drug Administration encouraged wider use of metformin in certain patients with kidney disease based on estimated glomerular filtration rate (eGFR) levels. But some providers haven’t fully embraced the importance of eGFR in evaluating the appropriateness of metformin, Dr. Bzowyckyj says. “We’ve all been so entranced by looking at serum creatinine since 1994,” when metformin was introduced in the United States, he says. “There’s 20 years of history you have to undo.”

Dr. Bzowyckyj of the University of Missouri-Kansas City School of Pharmacy, and Ashley Crowl, PharmD , BCACP, of the School of Pharmacy at the University of Kansas, spoke about the importance of eGFR at the annual meeting of the American Association of Diabetes Educators.

At issue has been the high rate of chronic kidney disease in diabetics. According to the Centers for Disease Control and Prevention , in 2011, about 50,000 people in the United States began treatment for kidney failure caused by diabetes. And almost 230,000 people were on dialysis or had gotten kidney transplants necessitated by kidney failure that year.

“Educators need to realize their role is not only to manage diabetes but also prevent and educate about concurrent kidney disease,” according to Dr. Bzowyckyj. “We want to empower educators to know they can make a difference.”

It’s important to understand that the serum creatinine level (SCr) itself shouldn’t be used alone to determine kidney function, the pharmacists noted. These tests provide some insight into kidney function by measuring the level of the waste product creatinine; higher levels are a sign that the kidneys aren’t removing waste properly.

But the levels can be misleading. “Some health care professionals see an elevated SCr and quickly label a patient with chronic kidney disease. But other factors need to be considered before providing this diagnosis. You cannot look at one SCr level, which can be increased or decreased by many factors.”

For example, “if you’re a body builder, you’ll have a high creatinine, but your kidneys could be just fine,” Dr. Bzowyckyj said. Dehydration, rhabdomyolysis, and medical problems related to pregnancy can also boost levels, while lower muscle mass and malnutrition can lower them.

Instead of basing the diagnosis on the SCr level alone, the two pharmacists recommended looking at the eGFR, a number that’s derived from a calculation that may include serum creatinine, weight, race, gender, and height. “It gives you a more clear picture of what’s happening,” Dr. Crowl said.

According to the National Kidney Foundation, eGFR in most healthy people is 90 mL/min per 1.73 m2 or above. An eGFR of less than 90 mL/min per 1.73 m2 for 3 months or more is a sign of kidney disease.

The two pharmacists said that it’s important for diabetes educators to monitor eGFR because it helps them get a better idea about whether they should urge a physician to adjust the medications taken by their patients. With the help of eGFR, “we can get more people more appropriately on metformin,” Dr. Crowl says.

The FDA is on board. In April, the agency announced labeling changes for metformin drugs “to expand metformin’s use in certain patients with reduced kidney function” and recommended that measurements such as eGFR be used instead of SCr to determine whether a patient with kidney disease should take metformin.

The FDA now believes that “metformin can be used safely in patients with mild impairment in kidney function and in some patients with moderate impairment in kidney function.” It is not recommended for those with severe cases, the agency has said.

Dr. Bzowyckyj and Dr. Crowl reported having no relevant financial disclosures.