Causes for an Enlarged Kidney

Enlarged kidneys are uncommon and are usually related to a few specific disorders that are caused by birth defects, structural abnormalities, infection, pregnancy, blockage and injury. An enlarged kidney can only be felt occasionally during an examination, usually when the patient is an infant, a child or a thin adult, according to the Merck Manual Online Medical Library. Other symptoms of kidney disease are usually identified first.

Enlarged kidneys have several possible causes. Credit: decade3d/iStock/Getty Images


Hydronephrosis is kidney enlargement due to a blockage in the outflow of urine that distends the kidney. According to Merck Manual Online Medical Library, hydronephrosis can be caused by a kidney stone, blood clot, prostate enlargement, fecal impaction, injury, infection, radiation, or a tumor. An enlarging uterus creating pressure can cause hydronephrosis of pregnancy. The main symptom of hydronephrosis is excruciating, intermittent flank pain. Chronic hydronephrosis may have no symptoms. Treatment includes relieving the cause of the blockage.

Polycystic Kidney Disease

According to, polycystic kidney disease, or PKD, is a disorder characterized by clusters of fluid-filled cysts within the kidney. Cysts also develop in other parts of the body, although the kidneys are most severely affected. Complications of PKD include high blood pressure and kidney failure due to progressive loss of function. Treatment of PKD involves managing the complications and symptoms such as hypertension, pain, urinary tract infections, kidney failure, liver cysts and aneurysms.


Pyelonephritis is an infection of the kidneys resulting from a bladder infection that spreads to the kidneys or from an infection in the blood. Signs and symptoms may include enlarged kidneys, tenderness on one or both sides of the lower back, chills, fever, painful and frequent urination, foul-smelling urine, cloudy urine and spasms that can cause intense pain. Antibiotics are used to treat the infection. Diabetics, pregnant women and those with a suppressed immune system are at higher risk of pyelonephritis.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.
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