• Screening For Chronic Kidney Disease

    The purpose of screening is early diagnosis and treatment. Screening tests are usually administered to people without current symptoms, but who may be at high risk for certain diseases or conditions. Individuals with the following conditions are at high risk:
    • Diabetes
    • Over 60 years
    • Hypertension
    • Strong family history of chronic kidney disease
    • Urinary obstruction
    • Medical diseases affecting the kidneys
    Early diagnosis and treatment of chronic kidney disease can prevent or delay complications. Since significant kidney disease is usually associated with a decrease in GFR and/or leakage of protein in the urine, the National Kidney Foundation recommends the following screening tests for people at increased risk for chronic kidney disease:
    Blood Creatinine Level
    Creatinine is a waste product that the kidneys usually remove from the blood. When the kidneys are damaged, the creatinine level rises. A simple blood test can measure the creatinine level, which is also used to calculate the glomerular filtration rate.
    Estimated Glomerular Filtration Rate
    The glomerular filtration rate (GFR) is a measurement of how well the kidneys are processing wastes. Your doctor can calculate the GFR based on your:
    • Sex
    • Age
    • Body size
    • Blood creatinine level
    The usual formula your doctor uses to estimate GFR is called the Cockcroft-Gault equation:
    Estimated GFR (mL per minute) = (140 – age) X body weight in kilogram ÷ 72 X serum creatinine. This product is multiplied by 0.85 if estimation is for a female patient.
    The GFR determines the stage of chronic renal disease.
    Stage Glomerular Filtration Rate (GFR)
    1 Over 90 mL/min (normal)
    2 60 to 89 mL/min(mild decrease)
    3 30 to 59 mL/min (moderate decrease)
    4 15 to 29 mL/min (severe decrease)
    5 under 15 mL/min (kidney failure)

    Urine Protein Level

    During the filtering process, the kidneys usually return protein to the circulation. With chronic kidney disease, the kidneys allow protein to leak into the urine. Different kinds of proteins can leak into the urine. Albumin is a protein that often appears in the urine of people who have chronic kidney disease caused by high blood pressure or diabetes.
    The guidelines of the National Kidney Foundation recommend two tests to check the urine protein level:
    • Protein-to-creatinine ratio
    • Albumin-to-creatinine ratio
    To perform these tests, the laboratory compares the amount the protein or albumin to the amount of creatinine in a urine sample.
    Depending on your risk factors, your doctor may also order the following screening tests:
    Serum Electrolytes
    Electrolytes, such as sodium and potassium, are minerals needed for the body to work well. Chronic kidney disease causes changes in the electrolytes. A simple blood test can measure the levels of these substances.
    Urine Concentration
    Chronic kidney disease causes changes in the concentration of the urine. A simple test can measure the urine concentration.
    Urine pH
    Chronic kidney disease causes changes in the pH, or acid level, of the urine. A simple test can measure the urine pH.


    Are you at increased risk for chronic kidney disease? National Kidney Foundation website. Available at: http://www.kidney.org/atoz/pdf/11-10-1814.pdf . Accessed September 10, 2011.

    Hallan SI, Dahl K, Oien CM, et al. Screening strategies for chronic kidney disease in the general population: follow-up of cross sectional health survey. Brit Med J. 2006;333:1047-1053.

    Johnson CA, Levey AS, Coresh J, Levin A, Lau J, Eknoyan G. Clinical practice guidelines for chronic kidney disease in adults: Part II. glomerular filtration rate, proteinuria, and other markers. Am Fam Phys. 2004; 70:1091-1097.

    K/DOQI clinical practice guidelines for chronic kidney disease: evaluation, classification, and stratification. National Kidney Foundation website. Available at: http://www.kidney.org/professionals/kdoqu/guidelines%5Fckd?p9Papproach.htm . Accessed July 30, 2005.

    Snively CS, Gutierrez C. Chronic kidney disease: prevention and treatment of common complications. Am Fam Phys. 2004;70:1921-1930.

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