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Definition

Some health problems that affect a kidney can cause pain. You might feel kidney pain as a dull, one-sided ache in your upper stomach area, side or back. But pain in these areas often has other causes that aren't related to the kidneys.

The kidneys are a pair of small organs in the back of the stomach area under the lower ribs. One kidney is located on each side of the spine. It's more common to have kidney pain, also called renal pain, on just one side of the body. Fever and urinary symptoms often happen along with kidney pain.

Causes

Many things can cause kidney pain. It can be due to health problems such as:

• Bleeding in the kidney, also called a hemorrhage.
• Blood clots in kidney veins, also called renal vein thrombosis.
• Dehydration
• Kidney cysts (fluid-filled pouches that form on or in the kidneys)
• Kidney stones (Hard buildups of minerals and salt that form inside the kidneys.)
• Kidney trauma, which could be caused by an accident, a fall or contact sports.

Some diseases that can cause kidney pain are:

• Hydronephrosis (which is swelling in one or both kidneys)
• Kidney cancer or a kidney tumor
• Kidney infection (also called pyelonephritis)
• Polycystic kidney disease (a genetic illness that causes cysts to form in the kidneys)

You could have one of these health problems and not have kidney pain. For example, most kidney cancers don't cause symptoms until they're advanced.

When to see a doctor

Call your health care provider right away if you feel constant, dull, one-sided pain in your back or side. Ask for a same-day appointment if you also:

• Have fever, body aches and fatigue.
• Had a recent urinary tract infection.
• Feel pain when you pee.
• See blood in your urine.
• Have an upset stomach or vomiting.

Get emergency care if you have sudden, serious kidney pain, with or without blood in your urine.