Diagnosis and Evaluation of Patients with Chronic Kidney Disease: Recommendations from the National Kidney Foundation

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The summary below is from the full report titled "National Kidney Foundation Practice Guidelines for Chronic Kidney Disease: Evaluation, Classification, and Stratification." It is in the 15 July 2003 issue of Annals of Internal Medicine (volume 139, pages 137-147). The authors are A.S. Levey, J. Coresh, E. Balk, A.T. Kausz, A. Levin, M.W. Steffes, R.J. Hogg, R.D. Perrone, J. Lau, and G. Eknoyan.

Who developed these guidelines?

The National Kidney Foundation, which is concerned with the care of people with kidney disease.

What is the problem and what is known about it so far?

The kidneys filter out wastes and water from the blood. Chronic kidney disease causes kidney function to worsen over time until dialysis is needed. Dialysis uses machines to filter the blood. Caring for kidney disease involves controlling diet, blood pressure, and medications to delay heart complications and the need for dialysis. Unfortunately, many patients do not know that they have chronic kidney disease and do not get care to delay complications. Risk factors include older age, family history of kidney disease, African-American ethnic background, diabetes, and high blood pressure. In 2002, the National Kidney Foundation developed recommendations for chronic kidney disease as part of an effort to improve quality of care. This article presents recommendations about the care of the early stages of chronic kidney disease.

How did the National Kidney Foundation develop these recommendations?

A group of experts reviewed studies on the early care of chronic kidney disease. If high-quality studies showed that a particular practice improved outcomes, they strongly recommended the practice ("level A" recommendation). If studies were of medium quality, they simply recommended it ("level B" recommendation). If studies were not available, they based a recommendation on expert opinions and only suggested that doctors consider the practice ("level C" recommendation).

What did the authors find?

The authors found strong evidence that patients do better if doctors detect kidney disease early and classify the stage of disease by determining glomerular filtration rate (GFR) (level A). Glomerular filtration rate, which is a measure of how well the kidneys work, is determined by testing blood and urine samples. The authors found medium-quality studies showing that patients benefit from seeing kidney specialists (nephrologists) when the GFR is less than 30 mL/min per 1.73 m² (level B). Studies were not available, but the authors suggest that doctors look for kidney disease risk factors in all patients and measure GFR in all patients with risk factors (level C). The authors found strong evidence that it was best to measure GFR by using one of two equations that consider patient characteristics in addition to the blood and urine test results (level A). They also found strong evidence that single urine samples (rather than samples collected over 24 hours) are sufficient to monitor kidney disease (level A).

What does the National Kidney Foundation suggest that patients and doctors do?

Patients and doctors should think about risk factors for kidney disease as part of usual care. Patients who have risk factors should be tested for kidney disease. Doctors should test patients using one of the standard equations for GFR. If kidney disease is present, patients and doctors should attempt to control diabetes, blood pressure, and other factors that influence the disease. Patients and doctors should consider referral to a nephrologist when the GFR is less than 30 mL/min per 1.73 m².

What are the cautions related to these recommendations?

Patient care should consider each patient's individual situation in addition to these recommendations.