Medullary sponge kidney, also known as Cacchi-Ricci disease, is a birth defect where changes occur in the tubules, or tiny tubes, inside a fetus’ kidneys.
In a normal kidney, urine flows through these tubules as the kidney is being formed during a fetus’ growth. In medullary sponge kidney, tiny, fluid-filled sacs called cysts form in the tubules within the medulla—the inner part of the kidney—creating a spongelike appearance. The cysts keep urine from flowing freely through the tubules.
Symptoms of medullary sponge kidney do not usually appear until the teenage years or the 20s. Medullary sponge kidney can affect one or both kidneys.
Complications of medullary sponge kidney include
Scientists do not fully understand the cause of medullary sponge kidney or why cysts form in the tubules during fetal development. Even though medullary sponge kidney is present at birth, most cases do not appear to be inherited.
Medullary sponge kidney affects about one person per 5,000 people in the United States. Researchers have reported that 12 to 20 percent of people who develop calcium-based kidney stones have medullary sponge kidney.1
Medullary sponge kidney affects all races and geographic regions. Among people who are more likely to develop calcium-based kidney stones, women are more likely than men to have medullary sponge kidney.2
Many people with medullary sponge kidney have no symptoms. The first sign that a person has medullary sponge kidney is usually a UTI or a kidney stone. UTIs and kidney stones share many of the same signs and symptoms:
People who experience these symptoms should see or call a health care provider as soon as possible.
A health care provider diagnoses medullary sponge kidney based on
Taking a medical and family history can help diagnose medullary sponge kidney. A health care provider will suspect medullary sponge kidney when a person has repeated UTIs or kidney stones.
No physical signs are usually present in a patient with medullary sponge kidney, except for blood in the urine. Health care providers usually confirm a diagnosis of medullary sponge kidney with imaging studies.
Imaging is the medical term for tests that use different methods to see bones, tissues, and organs inside the body. Health care providers commonly choose one or more of three imaging techniques to diagnose medullary sponge kidney:
A radiologist—a doctor who specializes in medical imaging—interprets the images from these studies, and patients do not need anesthesia.
In an intravenous pyelogram, a health care provider injects a special dye, called contrast medium, into a vein in the patient’s arm. The contrast medium travels through the body to the kidneys. The kidneys excrete the contrast medium into urine, which makes the urine visible on an x-ray. An x-ray technician performs this procedure at a health care provider’s office, an outpatient center, or a hospital. An intravenous pyelogram can show any blockage in the urinary tract, and the cysts show up as clusters of light.
Computerized tomography scans use a combination of x-rays and computer technology to create images. For a CT scan, a health care provider may give the patient a solution to drink and an injection of contrast medium. CT scans require the patient to lie on a table that slides into a tunnel-shaped device where the x-rays are taken. An x-ray technician performs the procedure in an outpatient center or a hospital. CT scans can show expanded or stretched tubules.
Ultrasound uses a device, called a transducer, that bounces safe, painless sound waves off organs to create an image of their structure. A specially trained technician performs the procedure in a health care provider’s office, an outpatient center, or a hospital. Ultrasound can show kidney stones and calcium deposits within the kidney.
Scientists have not discovered a way to reverse medullary sponge kidney. Once a health care provider is sure a person has medullary sponge kidney, treatment focuses on
To treat a UTI, the health care provider may prescribe a medication called an antibiotic that kills bacteria. The choice of medication and length of treatment depend on the person’s medical history and the type of bacteria causing the infection.
Treatment for kidney stones usually depends on their size and what they are made of, as well as whether they are causing pain or obstructing the urinary tract. Kidney stones may be treated by a general practitioner or by a urologist—a doctor who specializes in the urinary tract.
Small stones usually pass through the urinary tract without treatment. Still, the person may need pain medication and should drink lots of liquids to help move the stone along. Pain control may consist of oral or intravenous (IV) medication, depending on the duration and severity of the pain. People may need IV fluids if they become dehydrated from vomiting or an inability to drink.
A person with a larger stone, or one that blocks urine flow and causes great pain, may need more urgent treatment, such as
Scientists have not yet found a way to prevent medullary sponge kidney. However, health care providers can recommend medications and dietary changes to prevent future UTIs and kidney stones.
Health care providers may prescribe certain medications to prevent UTIs and kidney stones:
People with medullary sponge kidney should talk with their health care provider or a dietitian before making any dietary changes. A dietitian can help a person plan healthy meals.
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This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. The NIDDK translates and disseminates research findings through its clearinghouses and education programs to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by the NIDDK is carefully reviewed by NIDDK scientists and other experts.
The NIDDK would like to thank:
Deepa Chand, M.D., Akron Children’s Hospital; Maria Ferris, M.D., University of North Carolina; Joseph Flynn, M.D., M.S., Seattle Children’s Hospital; Keith Lau, M.D., McMaster University, Hamilton, Ontario; Tej Mattoo, M.D., Children’s Hospital of Michigan, Detroit; Asha Mougdil, M.D., Children’s National Medical Center, Washington, D.C.; and Robert Weiss, M.D., Maria Fareri Children’s Hospital, all members of the American Society of Pediatric Nephrology Clinical Affairs Committee