Conditions · Nephrology and urology
Medullary sponge kidney and medullary cystic disease !
Sponge kidney: small cysts in the collecting ducts that favour stones and infection. Medullary cystic disease: an inherited cause of kidney failure.
Updated 2026-11-01
Structures involved
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Why it happens
- Renal handling of calcium, phosphate and magnesium
- Renal handling of H⁺ and bicarbonate
- Kidney: cortex, medulla and the nephron
What it is
Medullary sponge kidney (Cacchi–Ricci disease) is a developmental disorder in which the collecting ducts of the renal pyramids are dilated into small cysts, giving the medulla a sponge-like look; it predisposes to stones, infection and haematuria but rarely to kidney failure. Medullary cystic kidney disease, now called autosomal dominant tubulointerstitial kidney disease (ADTKD), is a different, inherited disorder with tubulointerstitial fibrosis and small cysts at the corticomedullary junction that progresses to kidney failure in adulthood.
Who gets it
Medullary sponge kidney is found in roughly 1 in 5,000 people overall but in a notable share of people who form calcium stones; it is often diagnosed between ages 20 and 40. ADTKD is rare but probably underdiagnosed and is a cause of unexplained chronic kidney disease with a family history.
Causes
- Medullary sponge kidney: a disorder of kidney development, usually sporadic, rarely familial
- Medullary sponge kidney can occur with other developmental conditions such as hemihypertrophy
- ADTKD: autosomal dominant variants, mainly in the UMOD (uromodulin) and MUC1 genes
- Nephronophthisis, a related autosomal recessive disorder, causes kidney failure in childhood
Risk factors
- Family history of kidney stones or of kidney failure of unclear cause
- Recurrent calcium stones from a young age
- Hypercalciuria and low urinary citrate
Pathophysiology
In medullary sponge kidney the dilated collecting ducts let urine stagnate. Stasis, together with hypercalciuria, low citrate and sometimes distal tubular acidification defects, leads to tiny calcium stones in the ducts (nephrocalcinosis) and favours infection. In ADTKD, mutant uromodulin or mucin-1 accumulates in tubular cells, causing cell injury and interstitial fibrosis; uromodulin variants also impair urate handling, so hyperuricaemia and early gout are clues. Urinary sediment is bland and proteinuria is minimal.
Classification
- Medullary sponge kidney: usually bilateral, sometimes limited to a few pyramids
- ADTKD by gene: UMOD (early gout), MUC1, REN (anaemia, low blood pressure, high potassium) and HNF1B
- Nephronophthisis (autosomal recessive, childhood, polyuria and growth failure)
Symptoms and signs
- Often no symptoms in medullary sponge kidney
- Kidney stones with colicky flank pain
- Haematuria
- Recurrent urinary tract infections
- ADTKD: polyuria and nocturia from poor urine concentration, early gout
- ADTKD: slowly progressive kidney failure in adulthood with symptoms of uraemia
Diagnosis
- Clinical
- Suspect medullary sponge kidney in young adults with recurrent calcium stones and nephrocalcinosis; suspect ADTKD with slowly declining kidney function, bland urine, early gout and an affected parent.
- Tests
- Urinalysis and culture, creatinine, calcium, uric acid and bicarbonate; 24-hour urine for calcium, citrate, oxalate and volume. Genetic testing confirms ADTKD.
- Imaging
- CT urography shows contrast-filled dilated ducts with a "paintbrush" or "bouquet of flowers" pattern in the pyramids, plus medullary nephrocalcinosis on unenhanced CT. In ADTKD, ultrasound shows normal or small kidneys with few corticomedullary cysts.
Differential diagnosis
- Autosomal dominant polycystic kidney disease (enlarged kidneys, cortical and medullary cysts)
- Other causes of medullary nephrocalcinosis: distal renal tubular acidosis, primary hyperparathyroidism
- Renal papillary necrosis
- Chronic interstitial nephritis from drugs or toxins
- Renal tuberculosis
Goal of treatment
Prevent stones and infection in medullary sponge kidney; slow progression and prepare for kidney replacement in ADTKD.
Treatment
- Lifestyle
- High fluid intake to produce a dilute urine, moderate salt and animal protein, normal dietary calcium.
- Medical
- Drug prevention guided by urine studies: thiazide diuretics for hypercalciuria and potassium citrate for low citrate or acidosis.
- Medical
- Culture-guided antibiotics for urinary infections; urate-lowering therapy for gout in ADTKD.
- Procedure
- Stone removal by ureteroscopy, shock-wave lithotripsy or percutaneous surgery when stones obstruct or do not pass.
- Follow-up
- Follow-up of kidney function, blood pressure and stone activity; in ADTKD, genetic counselling, standard chronic kidney disease care and planning for dialysis or transplantation.
Complications
- Recurrent kidney stones and obstruction
- Pyelonephritis
- Nephrocalcinosis
- Chronic kidney disease and kidney failure (mainly in ADTKD)
- Gout (ADTKD from UMOD variants)
Prognosis
Medullary sponge kidney has a good long-term outlook; kidney failure is rare and depends on stones and infections. ADTKD usually progresses to kidney failure between the third and seventh decades and does not recur in a transplanted kidney.
Prevention
- Hydration and dietary measures to reduce stone recurrence
- Screening of relatives in families with ADTKD
Test yourself
Think of the answer, then tap the question to see it.
What is the typical CT urography appearance of medullary sponge kidney?
Linear streaks of contrast in dilated papillary ducts, a "paintbrush" or "bouquet of flowers" pattern.
What are the main complications of medullary sponge kidney?
Calcium kidney stones, nephrocalcinosis, haematuria and urinary infections; kidney failure is rare.
How is medullary cystic kidney disease inherited and what clue suggests the UMOD form?
Autosomal dominant; hyperuricaemia with early gout.
How does ADTKD differ from autosomal dominant polycystic kidney disease on imaging?
Kidneys are normal-sized or small with few medullary cysts, rather than enlarged with many cysts.
Related conditions
- Kidney stones (urolithiasis)
- Urinary tract infection (acute cystitis)
- Acute pyelonephritis
- Autosomal dominant polycystic kidney disease
- Renal tubular acidosis
- Chronic kidney disease
- Primary hyperparathyroidism
- Bartter, Gitelman and Liddle syndromes
- Gout
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Medullary Sponge Kidney - NIDDK (NIDDK (National Institutes of Health), 2024).
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Representative model, for educational purposes only.
