Is my kidney causing my back pain?

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Q. I have nagging back pain on my right side and I worry it might be my kidney. How can you tell when back pain is a problem with the kidney?

A. People commonly think their back pain comes from their kidney. But it’s more likely that your discomfort is due to muscle spasm or strain or a spine-related problem. The kidneys are located higher than most people realize (see image). So back pain, one of the most common problems that sends people to their doctors, is rarely due to kidney trouble. When pain is related to a kidney issue, not only is the pain higher up in the back, but the symptoms are also different.

For instance, a kidney stone that gets lodged in the ureter (the tube that runs from the kidney to the bladder) causes waves of intense pain rather than the steady ache of typical low back pain. And a person with a kidney infection (pyelonephritis) almost always has a fever along with flank pain.

If your pain is localized to the area of the kidney as shown in the illustration, you should see your doctor. Your doctor will tap on your flank to see if it is tender. He or she then will likely order a urine test to look for red and white blood cells and a blood test to make sure the kidneys are functioning normally. Based on these results, your doctor might also recommend an ultrasound or CT scan.

— Howard LeWine, M.D.
Editor in Chief, Harvard Men's Health Watch