According to 2002 statistics provided by the National Kidney & Urologic Diseases Information Clearinghouse, 1 out of every 5,000 to 20,000 people have medullary sponge kidney disease. The outside area of the kidney is called the cortex, while the inner area is the medulla, the area affected by this particular disease. The kidneys make the active form of vitamin D, but may not be able to do so when diseased.
Medullary Sponge Kidney Disease
Medullary sponge kidney disease is a hereditary disorder, but is usually not diagnosed until you are in your 40s or 50s. The disease occurs due to a mutation in chromosome 1 or chromosome 16, according to the “Current Medical Diagnosis & Treatment.” As a result, the medulla area in the kidneys becomes large and develops cysts, which makes the kidneys resemble a sponge. The kidney tubules, which collect urine, also get larger.
An infection can develop if the urine does not flow freely. The cysts interfere with the flow of urine, which can lead to an infection called pyelonephritis, an infection that involves the kidneys and the ureters that carry urine to the bladder. The irregular flow can also lead to kidney stones. In fact, some people with this disorder pass small kidney stones every once in a while, writes Jack McAninch, M.D., in “Smith’s General Urology.” They can also be low in vitamin D.
Vitamin D and the Kidneys
The normal range of calcium in the blood is 8.2 to 10.2 mg/dL. When the calcium level is low, the parathyroid gland secretes parathyroid hormone to the bones, which then release calcium. The kidneys then absorb more calcium and also convert the inactive form of vitamin D into the active form. The active form then signals the intestines to absorb more calcium, explains Elizabeth Corwin, Ph.D. in the “Handbook of Pathophysiology.” A kidney damaged by medullary sponge kidney disease may not be able to make the active form of the vitamin.
There is no treatment for this disorder, because physicians do not yet know how to treat the cysts, according to 2010 information from the National Kidney & Urologic Diseases Information Clearinghouse. A physician can treat any urinary infection resulting from the disease causes and possibly prescribe a low-dosage antibiotic for someone who has recurring bacterial infections to stop the infections and prevent recurrence. Surgery can treat kidney stones, while medication and/or a change of diet may prevent their development. If there is a vitamin D deficiency due to the damaged kidneys, vitamin D supplements can help.
- “Current Medical Diagnosis & Treatment 2011”; Stephen McPhee, M.D., Maxine Papadakis, M.D.; 2011
- “Handbook of Pathophysiology”; Elizabeth Corwin, MSN, Ph.D., FNP; 2000
- National Kidney & Urologic Diseases Information Clearinghouse; Medullary Sponge Kidney; Sept. 2, 2010
- “Smith’s General Urology”; Emil Tanagho, M.D., Jack McAninch, M.D.; 2008