Medullary sponge kidney
In medullary sponge kidney, the collecting ducts in the renal pyramids dilate, and cavities, clefts, and cysts form in the medulla. This disease may affect only a single pyramid in one kidney or all pyramids in both kidneys. The kidneys are usually somewhat enlarged but may be of normal size; they appear spongy.
Because this disorder is usually asymptomatic and benign, it’s often overlooked until the patient reaches adulthood. The prognosis is generally very good. Medullary sponge kidney is unrelated to medullary cystic disease; these conditions are similar only in the presence and location of the cysts.
Causes and incidence
Medullary sponge kidney may be transmitted as an autosomal dominant trait, but this remains unproven. Most nephrologists consider it a congenital abnormality.
Although medullary sponge kidney may be found in both sexes and in all age groups, it primarily affects males ages 40 to 70. It occurs in about 1 in every 5,000 to 20,000 persons.
Signs and symptoms
Symptoms usually appear only as a result of complications and are seldom present before adulthood. Complications include formation of calcium oxylate stones, which lodge in the dilated cystic collecting ducts or pass through a ureter, and infection secondary to dilation of the ducts. These complications, which occur in about 30% of patients, are likely to produce severe colic, hematuria, lower urinary tract infection ([UTI]; burning on urination, urgency, frequency), and pyelonephritis. Secondary impairment of renal function from obstruction and infection occurs in only about 10% of patients.
Diagnosis
Excretory urography is usually the key to diagnosis, often showing a characteristic flowerlike appearance of the pyramidal cavities when they fill with contrast material. It may also show renal calculi. Urinalysis is generally normal unless complications develop; however, it may show a slight reduction in concentrating ability or hypercalciuria. Diagnosis must distinguish medullary sponge kidney from renal tuberculosis, renal tubular acidosis, and papillary necrosis.
Treatment
Treatment focuses on preventing or treating complications caused by stones and infection. Specific measures include increasing fluid intake and monitoring renal function and urine. New symptoms necessitate immediate evaluation.
Because medullary sponge kidney is a benign condition, surgery is seldom necessary, except to remove stones during acute obstruction. Only serious, uncontrollable infection or hemorrhage requires nephrectomy.
Special considerations
Patient care includes explaining the disease to the patient and his family and reassuring them that the condition is benign and the prognosis good.
❑ To prevent infection, instruct the patient to bathe often and use proper toilet hygiene; this is especially important for a female patient because the proximity of the urinary meatus and the anus increases the risk of infection.
❑ If infection occurs, stress the importance of completing the prescribed course of antibiotic therapy.
❑ Emphasize the need for adequate fluid intake.
❑ Explain all diagnostic procedures, and provide emotional support. Teach the patient how to collect a clean-catch urine specimen for culture. Check for allergy to excretory urography dye.
❑ When the patient is hospitalized for a stone, strain all urine, administer analgesics as ordered, and force fluids. Before discharge, tell the patient to watch for and report any signs of stone passage and UTI.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2008 Williams & Wilkins.
More About Causes of Kidney failure
» Next page: Polycystic kidney disease (Professional Guide to Diseases (Eighth Edition))
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