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    Your Kidneys and How They Work

    How Will My Doctor Detect Kidney Disease? continued...

    Normal blood contains 7 to 20 milligrams of urea per deciliter of blood. If your BUN is more than 20 mg/dl, your kidneys may not be working at full strength. Other possible causes of an elevated BUN include dehydration and heart failure.

    Proteinuria

    Healthy kidneys take wastes out of the blood but leave in protein. Impaired kidneys may fail to separate the protein from the wastes. Proteinuria means protein in the urine, and it is a sign of poor kidney function. If your urine makes foam in the toilet, it may contain high levels of protein. Your doctor may test for protein using a dipstick in a small sample of your urine taken in the doctor's office. The color of the dipstick indicates the presence or absence of proteinuria. For a more precise measurement, you may need to collect urine for 24 hours.

    Additional Tests

    Renal imaging. If blood and urine tests indicate reduced kidney function, your doctor may recommend additional tests to help identify the cause of the problem. Renal imaging (taking pictures of the kidneys) methods include ultrasound, computed tomography (CAT scan), and magnetic resonance imaging (MRI). These tools are most helpful in finding unusual growths or blockages to the flow of urine.

    Renal biopsy. Your doctor may want to see a tiny piece of your kidney tissue under a microscope. To obtain this tissue sample, the doctor will perform a renal biopsy -- a hospital procedure in which the doctor inserts a needle through your skin into the back of the kidney. The needle retrieves a strand of tissue about 1/2 to 3/4 of an inch long. You will lie prone (on your stomach) on a table and will receive local anesthetic to numb the skin. The sample tissue will help the doctor identify problems at the cellular level.

    What Can I Do About Kidney Disease?

    Unfortunately, kidney disease cannot be cured. But if you are in the early stages of a kidney disease, you may be able to make your kidneys last longer by taking certain steps.

    • If you have diabetes, watch your blood sugar closely to keep it under control. Consult your doctor for the latest in treatment.
    • Have your blood pressure checked regularly. Talk with your doctor about the best medicine to keep your blood pressure under control.
    • Avoid pain pills that may make your kidney disease worse. Check with your doctor before taking any medicine.
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