Dr. med. Dirk Manski

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Medullary Sponge Kidney

Review literature: (Foster et al, 2007).

Definition of the Medullary Sponge Kidney

A medullary sponge kidney is a congenital malformation of the kidney with cystic enlargement and calcification of the collecting ducts.



In the majority of sporadic cases, the exact cause is unknown. In some patients with medullary sponge kidney, mutations can be detected in the RET (rearranged during transfection) and GDNF (glial cell line-derived neurotrophic factor) genes, the patients may also show extrarenal malformations (Ria et al, 2017).

Pathology of the Medullary Sponge Kidney

The distal collecting ducts are dilated and have cysts with a diameter of 1–8 mm. The cut surface of the renal medulla looks like a sponge. Calcifications (70% calcium phosphate and 30% calcium oxalate) develop within the cysts. In 75%, medullary sponge kidney is bilateral.

Signs and Symptoms of a Medullary Sponge Kidney

Diagnostic Work-Up of a Medullary Sponge Kidney

Ultrasound of the kidneys:


The contrast media fills the ectatic collecting ducts, the excretion is delayed: appearance suggestive of "bristles on a brush" [fig. medullary sponge kidney in urography]. With progression of the disease, calcifications are seen in the distal collecting ducts: appearance suggestive of a "bouquet of flowers".

fig. medullary sponge kidney with ectatic collecting ducts

Urography of a medullary sponge kidney: The contrast media fills the ectatic collecting ducts, the excretion is delayed: appearance suggestive of "bristles on a brush". With kind permission of Dr. G. Antes, Kempten.

Differential Diagnosis of Bilateral Renal Calcification:

Treatment of the Medullary Sponge Kidney

Treatment in medullary sponge kidney is only necessary in complications like nephrolithiasis, urinary tract infection or renal insufficiency.

Treatment of Nephrolithiasis:

Thiazide diuretics are suitable for the prevention of nephrolithiasis in nephrocalcinosis. Otherwise, the stone therapy does not differ to patients without medullary sponge kidney.

Treatment of Urinary Tract Infections:

Frequent urinary tract infections with coagulase-positive staphylococci should be treated even in non-significant number of bacteria according to the results of the urine culture.

Prognosis of Medullary Sponge Kidney

The risk of renal failure in medullary sponge kidney for symptomatic patients was reported to be 10% in previous studies. Due to improved minimally invasive stone therapy options, this figure should be lower nowadays.

Index: 1–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


Forster, J. A.; Taylor, J.; Browning, A. J. & Biyani, C. S.
A review of the natural progression of medullary sponge kidney and a novel grading system based on intravenous urography findings.
Urol Int, 2007, 78, 264-269

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