Chronic Kidney Disease (CKD) affects 1 in 3 Americans¹. According to the National Kidney Foundation, only 10% of individuals with CKD know they have the disease¹. 

Most attribute their symptoms to other causes until the very late stages of CKD. By then, their kidneys have begun to fail with large amounts of protein detected in their urine¹. Early detection and treatment are vital to help prevent kidney disease from spiraling downward to kidney failure.

Two-thirds of kidney disease cases are caused by diabetes or high blood pressure¹. Considering the 37 million people who have diagnosed CKD, 660,000 have experienced kidney failure. ¹ Risk factors or co-morbidities include high blood pressure, diabetes, a family history of the disease, age of 60-years or older, obesity, and heart disease¹.

Since signs and symptoms can be general or may not be obvious until late in the disease progression, kidney function should be assessed clinically for at-risk individuals. Two important quantitative measurements are glomerular filtration rate (GFR) and albumin-to-creatinine ratio (ACR).

GFR is a blood test which measures the efficacy of kidney function¹. There are two methods of determining GFR: eGFR and mGFR.  Estimated glomerular filtration rate (eGFR) is a measurement of kidney function that determines the rate of filtered fluid by using concentration of the most used serum filtration marker, creatinine. eGFR is calculated using specific estimation equations, that includes variation of serum creatinine concentration, age, gender and race. The eGFR is calculated relative to the body surface, 1.73 m² in adults, and should be reported in the units ml/min/1.73 m². An eGFR of >60 ml/min/1.73 m² is considered normal² Currently, the KDIGO guidelines recommend the use of CKD-EPI equation to calculate eGFR in adults. Creatinine is a breakdown product of creatinine phosphate from muscle and protein metabolism and serum creatinine levels are an important indicator of kidney health³. KDIGO guidelines recommend using an alternative filtration biomarker (serum cystatin C) to confirm a decreased eGFR calculated using serum creatinine⁴. 

The accuracy of this test can be affected by factors such as pregnancy, being over the age of 70, unusual muscle mass, cirrhosis, nephrotic syndrome, a past solid organ transplant, and certain medications.¹ eGFR measurements can fail to  detect  early GFR changes that includes rapid decrease in GFR levels as observed in diabetic kidney disease conditions¹.

mGFR is recommended for use as a confirmatory test, if there are inaccurate estimations of GFR using serum creatinine⁵. The mGFR is considered a complicated, expensive assay; so health care providers use the eGFR calculation as an estimate instead ⁶.

ACR tests the urine for albumin and creatinine. The ratio of albumin over creatinine is used quantitatively to detect albuminuria. Too much albumin in the urine is an early sign of kidney damage which may progress to CKD. Three positive results over three months or more is a sign of kidney disease.¹ The ranges for urine spot collection ACR are: normal at <30 mg/g; microalbuminuria from 30-300 mg/g and clinical albuminuria at >300 mg/g¹. Creatinine levels can also be affected by diet, muscle mass of the individual, malnutrition and other chronic diseases and should be considered when screening with ACR.

Current ADA guidelines for CKD recommend ACR and GFR at least annually for people with type 1 diabetes with a duration of > 5 years and in all individuals with type 2 diabetes⁵. In those with established diabetic CKD, those assays should be monitored 1-4 times per year depending on the stage of the disease⁵. A 2012 report published by KDIGO (Kidney Disease Improving Global Outcomes) suggests ACR as one of the measurements for the initial testing of proteinuria³. An early morning sample is preferred for this test.

In order to diagnose and monitor patients at risk for CKD, rapid point-of-care-tests (POCT) for ACR are available to quickly quantify these levels and help improve patient care.

The Afinion™ ACR assay is quick, and user friendly⁷.  It can determine albumin, creatinine and albumin/creatinine ratios in human urine in 5 minutes with no blood draws or finger pricks needed⁴. Afinion™ ACR can help identify early CKD and monitor its progression in patients with diabetes or hypertension by its use as a screening tool to quickly determine if other follow-up tests are needed.

For more information on Abbott’s Afinion™ ACR assay, please contact your Abbott Cardiometabolic Account Executive.