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Friday, March 7, 2014
Pain caused by the kidneys is typically felt in the flank area, which is in the back, just at the lower edge of the ribs on either side of the spine. Pain caused by the kidneys tends to be sharp and severe, to and occur in waves.
It is uncommon for the kidneys to cause dull, aching pain. People sometimes equate back pain with kidney pain, but aching pain in the back -- especially the lower back or the middle of the back -- is usually due to muscles, ligaments, or even vertebrae and disks in the spinal column. Musculoskeletal pain typically gets worse with movement, and is relieved by heat or massage.
Cause of pain: The pain caused by kidney stones occurs when a stone becomes lodged in the ureter, the slender tube that connects the kidney with the bladder. Urine flow is then blocked, which causes urine to back up into the kidney. The kidney then swells and enlarges, stretching the pain-sensitive capsule, or thin covering around it.
What to expect: The pain caused by kidney stones is referred to as "colic," meaning that it comes in waves as opposed to being a steady continuous pain. Pain from kidney stones is described as being almost as severe as that of childbirth. Patients with renal colic usually find it very difficult to hold still, and are in constant motion, pacing and writhing. Often the pain is so severe that it causes nausea and vomiting.
Although the pain starts in the right or left flank area, it may move as the stone travels down the ureter. The pain may move around the side of the trunk to the lower part of the abdomen in the front and even travel down to the groin.
Kidney Infection (also known as pyelonephritis)
Cause of pain: Pain caused by kidney infection (pyelonephritis) is related to infection and inflammation within the kidney tissue. Infection causes the kidney to swell, and stretches the pain-sensitive capsule surrounding the kidney, leading to a sharp, aching pain.
What to expect: Patients with kidney infection are very sensitive to even the lightest touch in the flank area. They are usually quite ill with the infection, and generally have high fever, nausea, and vomiting as well. Infection of the kidney is much more serious than the much more common condition of bladder infection. Pyelonephritis needs to be treated promptly with intravenous antibiotics in order to prevent spread of infection to the bloodstream and/or permanent kidney damage.
Less common causes of kidney pain are bleeding within the kidney (for instance, due to injury), or "infarction" of the kidney, where the blood supply is suddenly cut off because of blockage of the artery to the kidney.
As noted above, it is uncommon for the kidneys to be a cause of dull aching pain. In fact, it is extremely unusual for a slowly-occurring blockage from the conditions listed (even cancer) to cause any pain at all.
Kidney cancer: Rarely a kidney tumor, or cancer, can grow and stretch the kidney capsule slowly, or involve nerves in the kidney area, causing pain.
Polycystic kidney disease: A hereditary disease called polycystic kidney disease can lead to massive enlargement of the kidneys over a period of years and can sometimes cause a dull aching pain, which is usually felt in the front of the abdomen rather than in the back.
Blocked urine flow: There are also some conditions that may cause a gradual blockage to urine flow (not a sudden blockage like that of a kidney stone); in these cases the kidney may be stretched and cause a dull aching pain.
Bladder or ureteral spasm: When the bladder is very full, just before or during urination, one may feel discomfort in the lower abdominal or even flank area. This discomfort is probably not coming directly from the kidneys, but may be related to peristalsis (involuntary muscle contraction) in either the ureters or the bladder. Even though there may be a brief period of muscle spasm, which presumably causes the discomfort, the sensation should quickly resolve soon after the bladder is emptied.
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Last Reviewed: Sep 03, 2013
Mildred Lam, MD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University