A number of disorders can cause flank pain, some of these are associated with the kidneys, some are not. Note, however, that some kidney disorders present without any noticeable symptoms. Kidney disorders that do cause side or flank pain include:
Kidney Infection: A kidney infection can be acute or chronic and may be an indication of an underlying health condition, such as diabetes. Chronic forms can lead to scarring and kidney failure. Pain from an infection lasts only as long as the infections lasts. Prompt treatment minimizes the length of time flank pain persists.
Kidney Cancer: Renal cell carcinoma (RCC) is the most common type of kidney cancer. RCC begins in the tubules, the tiny looping blood vessels in the kidney's waste-filtering nephrons. Symptoms are usually not detectable in the early stages, but as the disease progresses, persistent back and flank pain can occur.
Kidney Cysts: Most types of kidney cysts are hereditary. These include polycystic kidney disease (PKD), medullary cystic kidney disease (MCK) and medullary sponge kidney (MSK). Symptoms and treatment vary by cyst type.
Kidney Stones/Calculi: Kidney stones may be made up of several different substances. By far the most common types are calcium-based, either from calcium oxalate or calcium phosphate. Uric acid formations are also common. The pain of a kidney stone resolves when the stone is passed or removed.
A number of other conditions cause discomfort, back spasms and other symptoms that mimic kidney disorders.
Lower Back Injury: A lower back injury is one of the most common causes of flank pain not associated with the kidneys, and is initially often confused with kidney pain. The biggest difference in the two types of pain is that flank pain due to a back injury generally doesn't worsen when palpated (pushed on), whereas kidney pain will worsen with palpation.
Appendicitis: Appendicitis is an inflammation of the appendix. The main symptom is pain in the lower-right side of the abdomen that continues to increase in severity over a period of six to twelve hours. Once the pain begins, the only medical procedure available is surgery to remove the appendix before it bursts, which may result in infection, or even death.
Ectopic Pregnancy: An ectopic pregnancy occurs when a fertilized ovum develops outside of the uterus. An ectopic pregnancy can occur in the fallopian tubes, or even in the abdominal cavity. Ectopic pregnancy can cause lower abdominal cramping, side pain and lower back pain.
Gallstones: Gallstones are calculi, or mineral buildups, that occur in the gallbladder. Gallstones can block the flow of bile in ducts that connect the liver to the small intestine. If blocked, the bile trapped in the ducts can cause inflammation in the gallbladder, liver, or pancreas. Prolonged blockage may result in severe damage to the organs. Upper abdominal, back and flank pain occur for thirty minutes or more. Gallstones commonly develop during pregnancy.
Hepatitis: Hepatitis is an inflammation of the liver. Infections and alcohol abuse are among the main causes of hepatitis. Regardless of the type of hepatitis, symptoms include jaundice, fever, dark urine, joint pain, abdominal and flank pain. Occasionally, hepatitis may cause liver failure.
Shingles: Shingles is a reactivation of the chickenpox virus in adults. The inactive virus resides in the nerves coming out of the spine. When reactivated the virus spreads along the nerves causes flank pain and after two to three days an ulcerative skin rash in a one-sided belt from the spine around the side to the breastbone. In some cases flank pain can continue for months after the rash has healed. This is called "post-herpetic" neuralgia and is due to the irritation of the nerves.
Stomach ulcers: Stomach ulcers occur when gastric juices eat into the stomach lining or duodenum. The result is a burning pain in the stomach. Infection with the bacteria Helicobacter pylori (H. pylori) is the primary cause of stomach ulcers. Other symptoms of ulcers include nausea, vomiting, and loss of appetite. Flank pain of stomach ulcers is actually due to the intestinal distress caused by the ulcers.
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National Digestive Diseases Information Clearinghouse. (updated 1998). Peptic ulcers. [NIH Publication No. 95-38].
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