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Nephronophthisis–medullary
cystic disease complex is a group of disorders in which fluid-filled
sacs (cysts) develop deep within the kidneys, leading to kidney
failure.
Nephronophthisis–medullary cystic disease complex is a group of hereditary disorders that affect the development of microscopic tubules deep within the kidneys that concentrate the urine and reabsorb sodium. The damaged tubules become inflamed and scarred, eventually causing kidney failure.
Nephronophthisis is inherited as an autosomal recessive disease, so one defective gene must be received from each parent. It causes symptoms that usually begin during childhood or early adolescence and usually leads to kidney failure in early adolescence.
Medullary cystic
disease is inherited as an autosomal dominant disorder, so a defective gene from only one parent is necessary, and it usually causes symptoms that begin in adulthood. Occasionally, the disorder occurs in a person with no family history of kidney disease. These people may have developed the gene defect as a new mutation (the gene becomes abnormal for no apparent reason) or the defect was present but not recognized in one or both parents.
Symptoms and
Diagnosis
A person starts to produce excessive amounts of urine and becomes excessively thirsty because the kidneys become unable to concentrate urine and conserve sodium.
With nephronophthisis, the symptoms begin in children age one year or older and are associated with retarded growth. People with nephronophthisis may have eye disorders, liver disorders, and mental retardation. Later in childhood, kidney failure may produce anemia, nausea, and weakness.
With medullary cystic disease, the symptoms develop in adolescence or early adulthood. Excessive thirst and abnormal urine production are not as severe as with nephronophthisis. Other organs are not affected. Kidney failure occurs usually between the ages of 34 and 65. Some people develop gout.
Family history of this type of kidney disease is an important clue to the diagnosis. Laboratory tests indicate poor kidney function and a low level of sodium in the blood. Computed tomography (CT) is the imaging test that is most likely to detect cysts. In the future, genetic testing may become the most precise method of making the diagnosis.
Treatment
When kidney failure occurs, dialysis or kidney transplantation is needed. Particularly in nephronophthisis, large daily intake of fluids and salt (sodium) is needed to compensate for the excessive excretion of sodium and the production of large volumes of dilute urine.
Last full review/revision December 2006 by Peter C. Brazy, MD
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