History
Patients with medullary sponge kidney often are asymptomatic. Not infrequently, the diagnosis is made during radiologic investigations, including abdominal radiography and excretory pyelography, performed for other clinical situations. [6, 7]
Hematuria is frequent, and gross hematuria may be present in 10-20% of cases. Gross hematuria usually results from pelvic obstruction due to stones. Microscopic hematuria may be present with or without urinary tract infection (UTI). (See Table 1, below.)
Renal stones also result in UTI, urinary obstruction, and nephrocalcinosis. The stones in medullary sponge kidney are usually composed of calcium phosphate (apatite) and calcium oxalate. (See Table 1, below.)
UTI is common in medullary sponge kidney, with and without nephrolithiasis. Sterile pyuria also is common. Patients with medullary sponge kidney have more UTIs than other patients with nephrolithiasis, and the incidence of urinary infection is higher in women than in men. (See Table 1, below.)
Recurrent nephrolithiasis is a major complication of medullary sponge kidney. The most common presenting symptom of this complication is renal colic, often accompanied by hematuria. (See Table 1, below.)
Table 1. Clinical Features of Medullary Sponge Kidney and Etiologic Correlation (Open Table in a new window)
Frequency |
Clinical Findings |
Etiology |
Common* |
Nephrolithiasis (calcium oxalate, calcium apatite) |
Hypercalciuria Increased oxalate concentration Tubular acidification defects Hypocitraturia |
Hematuria (gross 10-20%, microscopic) |
Acute pelvic obstruction UTI, renal stones, or absence of both |
|
UTI |
Sterile pyuria common even in absence of stones Presence of renal stones |
|
Rare |
Chronic kidney disease |
Repeated urinary obstruction Repeated pyelonephritis due to urease-producing organisms (Proteus) |
*Asymptomatic |
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Medullary sponge kidney can occur in conjunction with other congenital abnormalities, as follows:
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Anodontia
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Autosomal dominant polycystic kidney
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Beckwith-Wiedemann syndrome
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Caroli syndrome
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Congenital hemihypertrophy - As many as 10% of patients with hemihypertrophy have medullary sponge kidney, and as many as 25% of patients with medullary sponge kidney have hemihypertrophy
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Congenital pyloric stenosis
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Distal renal tubular acidosis
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Ehlers-Danlos syndrome
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Horseshoe kidney
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Marfan syndrome
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Parathyroid adenomas
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Renal artery stenosis
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Ureteral duplication
When associated with medullary sponge kidney, Beckwith-Wiedemann syndrome (high birth weight, macroglossia, omphalocele, visceromegaly, mental retardation, cysts in the adrenal cortex, enlarged kidneys, medullary sponge kidney, and hemihypertrophy) has a high tumor rate, especially Wilms tumor, adrenal gland cancer, and hepatoblastoma.
If any suggestion of a history of medullary sponge kidney in other family members exists, further investigations may be indicated to unravel the genetic pattern of transmission.
Physical Examination
The following may be encountered on physical examination:
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No physical findings are usually present except for hematuria
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Renal colic may occur
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Costovertebral angle tenderness occurs in cases of pyelonephritis or ureteral obstruction by a calculus
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Hemihypertrophy is present in 25% of cases
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Other signs of associated congenital disorders may be present (as listed in the History section)
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IVU-like, volume-rendered (VR) computed tomography (CT) scan of both kidneys demonstrates brushlike densities throughout multiple papillae of both kidneys consistent with renal tubular ectasia. Correlation of the stone disease with the ectatic tubules is diagnostic of medullary sponge kidney. Image courtesy of Dr. Terri J. Vrtiska, Consultant, Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
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Unenhanced coronal, volume-rendered (VR) computed tomography (CT) scan of the kidneys demonstrates 2 small calculi in the midportion of the right kidney and 2 small calculi in the lower pole of the left kidney (arrowheads). A large, low-density lesion in the lower pole of the right kidney and a small, low-density lesion in the upper pole of the left kidney (short arrows) were shown to represent benign simple renal cysts on the contrast-enhanced CT scans. Image courtesy of Dr. Terri J. Vrtiska, Consultant, Department of Radiology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
Tables
Frequency |
Clinical Findings |
Etiology |
Common* |
Nephrolithiasis (calcium oxalate, calcium apatite) |
Hypercalciuria Increased oxalate concentration Tubular acidification defects Hypocitraturia |
Hematuria (gross 10-20%, microscopic) |
Acute pelvic obstruction UTI, renal stones, or absence of both |
|
UTI |
Sterile pyuria common even in absence of stones Presence of renal stones |
|
Rare |
Chronic kidney disease |
Repeated urinary obstruction Repeated pyelonephritis due to urease-producing organisms (Proteus) |
*Asymptomatic |
||
Radiologic Test |
Appearance |
Plain radiograph |
Normal or enlarged kidney Medullary nephrocalcinosis indicated by isolated, single or multiple precaliceal concretions or clusters of grapelike calcifications |
Excretory urogram* |
Papillary blush Faint pyramidal striation Papillary streaking or brushlike appearance Precaliceal tubular dilatation filled with contrast Papillary blush and multiple precaliceal dilatation Bouquet of flowers |
CT scan |
Papillary calcification Hyperdense papilla Ectasia of precaliceal tubules |
*Findings limited to medullary pyramids |
|
