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Medullary Sponge Kidney

By

Enrica Fung

, MD, MPH, Loma Linda University School of Medicine

Last full review/revision Apr 2021| Content last modified Apr 2021
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Medullary sponge kidney is formation of diffuse, bilateral medullary cysts caused by abnormalities in pericalyceal terminal collecting ducts.

The cause of medullary sponge kidney is unknown, but genetic transmission occurs in < 5% of cases.

Most patients are asymptomatic, and the disorder usually remains undiagnosed. It predisposes to calculus formation (often with increased urinary calcium excretion) and urinary tract infection Introduction to Urinary Tract Infections (UTIs) Urinary tract infections (UTIs) can be divided into upper tract infections, which involve the kidneys (pyelonephritis), and lower tract infections, which involve the bladder (cystitis), urethra... read more (UTI), so the most common presenting symptoms are the following:

Medullary sponge kidney is benign, and long-term prognosis is excellent. Obstruction by renal calculi Urinary Calculi Urinary calculi are solid particles in the urinary system. They may cause pain, nausea, vomiting, hematuria, and, possibly, chills and fever due to secondary infection. Diagnosis is based on... read more may transiently reduce glomerular filtration rate (GFR) and increase serum creatinine.

Diagnosis of Medullary Sponge Kidney

  • CT or intravenous urography (IVU)

The diagnosis is suspected in patients with recurrent calculi or UTIs or on the basis of incidental radiographic findings such as medullary nephrocalcinosis and dilated contrast-filled collecting ducts. Urinalysis typically shows evidence of incomplete distal renal tubular acidosis Renal Tubular Acidosis Renal tubular acidosis (RTA) is acidosis and electrolyte disturbances due to impaired renal hydrogen ion excretion (type 1), impaired bicarbonate resorption (type 2), or abnormal aldosterone... read more (overt metabolic acidosis is rare) and decreased urine-concentrating ability in patients without symptomatic polyuria.

Diagnosis is generally confirmed by CT, but IVU can be used. Ultrasonography is not helpful because cysts are small and located deep in the medulla.

Treatment of Medullary Sponge Kidney

  • Control of complications (eg, UTI, renal calculi)

Treatment is indicated only for UTIs Introduction to Urinary Tract Infections (UTIs) Urinary tract infections (UTIs) can be divided into upper tract infections, which involve the kidneys (pyelonephritis), and lower tract infections, which involve the bladder (cystitis), urethra... read more and for recurrent calculus formation Urinary Calculi Urinary calculi are solid particles in the urinary system. They may cause pain, nausea, vomiting, hematuria, and, possibly, chills and fever due to secondary infection. Diagnosis is based on... read more . Thiazide diuretics (eg, hydrochlorothiazide 25 mg orally once/day) and high fluid intake may inhibit calculus formation by reducing urinary calcium excretion and preventing urinary stasis. These effects may reduce incidence of obstructive complications in patients with recurrent calculi.

Drugs Mentioned In This Article

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MICROZIDE
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