Hypertension in a patient with medullary sponge kidney: A case report

RATIONALE

Medullary sponge kidney (MSK) is a congenital renal disorder characterized by recurrent nephrolithiasis or nephrocalcinosis. Recently, it has been found that MSK can be also combined with other diseases, such as primary aldosteronism and Beckwith-Wiedemann, but whether it is associated with secondary hypertension remains unknown.

PATIENT CONCERNS

A 22-year-old hypertensive female presented to our hospital characterized by hypokalemia and hypertension.

DIAGNOSIS

The laboratory examination showed secondary aldosteronism. And the common causes for secondary aldosteronism include renal artery stenosis, glomerulonephritis, lupus nephropathy, and diabetic nephropathy, all of which were excluded except MSK.

INTERVENTIONS

She was treated with angiotensin-converting enzyme inhibitors.

OUTCOMES

Her blood pressure, serum potassium, and plasma renin levels were reversed after treatment with angiotensin-converting enzyme inhibitors.

LESSONS

We presumed that MSK may be associated with secondary hypertension, and the mechanism may be the activation of the renin-angiotensin-aldosterone system.

Lithiasis in cystic kidney disease and malformations of the urinary tract

The prevalence of renal stones in renal cystic and malformative conditions exceeds the prevalence of renal stones in the general population, suggesting that the above-mentioned cystic and malformative disorders favor stone formation. Urinary stasis is generally assumed to play a major part in the pathogenesis of the nephrolithiasis associated with distorted renal anatomy due to a delayed washout of crystals and risk of urinary infections. However metabolic factors are also important in the pathogenesis of stones in these conditions. Indeed, metabolic abnormalities have been observed in the majority of stone-forming patients with conditions such as horseshoe kidney and ureteropelvic junction obstruction. Five different models of stone formation can be identified, depending on stone composition, risk of infection stones, and pathogenesis of renal cystic and malformative conditions. A proper metabolic evaluation should be conducted to diagnose specific, treatable metabolic disorders, thereby reducing the frequency of recurrent stone disease in these conditions as well.

Renal tubular dysfunction in patients with cystic disease of the kidneys

OBJECTIVE

To define the renal tubular functional abnormalities in patients with cystic disease of the kidneys.

METHODS

Patients with autosomal dominant polycystic kidney disease (ADPKD) (n = 4) and medullary sponge kidneys (MSK) (n = 3) with normal glomerular filtration rate (GFR), determined by inulin clearance, and effective renal plasma flow (ERPF), measured by p-aminohippurate clearance, underwent measurement of proximal and distal tubular functions. Proximal tubular functions were determined by the maximum reabsorption of glucose (TmGlucose) and the maximum secretion of p-aminohippurate (TmPAH). Distal tubular functions were measured by the maximum urinary concentrating and diluting mechanisms, and the urinary acidification response to acid load.

RESULTS

TmGlucose was low in both groups (209 +/- 25 mg/min/1.73 m2 in the ADPKD group and 110 +/- 28 mg/min/1.73 m2 in the MSK, compared with 375 +/- 40 mg/min/1.73 m2 in healthy controls; P < 0.05). Likewise, TmPAH was significantly diminished in patients with ADPKD (72 +/- 6 mg/min/1.73 m2) and MSK (63 +/- 5 mg/min/1.73 m2) when compared with healthy controls (89 +/- 4 mg/min/1.73 m2; P < 0.05). Urinary maximum concentration after fluid deprivation was impaired in both ADPKD and MSK patients, but the diluting mechanism was intact. Finally, the ability to excrete urinary ammonium and titratable acids following an oral acid load was inadequate in both the ADPKD and MSK groups.

CONCLUSIONS

Proximal and distal tubular functions are impaired in patients with ADPKD and MSK when GFR and ERPF are normal, indicating tubular disruption by the cysts and the alteration of the tubulo-interstitial vascular relationship.

Medullary sponge kidney associated with congenital hemihypertrophy

Medullary sponge kidney is a developmental disorder characterized by ectatic and cystic malformation of the collecting ducts and tubules. Clinical manifestations include urinary tract infections, renal stones, and hematuria. It can be associated with other developmental disorders. A case of medullary sponge kidney associated with congenital hemihypertrophy, complicated by nephrocalcinosis and nephrolithiasis, is reported here.

Renal acidification defects in medullary sponge kidney

Thirteen patients with medullary sponge kidney underwent a short ammonium chloride loading test to investigate their renal acidification capacity. All but 1 presented with a history of recurrent renal calculi and showed bilateral widespread renal medullary calcification on X-ray examination. Nine patients had some form of renal acidification defect; 8 had the distal type of renal tubular acidosis, 2 the complete and 6 the incomplete form. One patient had proximal renal tubular acidosis. These findings, which suggest that renal acidification defects play an important role in the pathogenesis of renal calculi in medullary sponge kidney, have considerable therapeutic implications.

Unilateral and segmental medullary sponge kidney: renal function and calcium excretion

The renal acidification defect and renal hypercalciuria have been reported in patients with pan-renal and bilateral medullary sponge kidney. However, little is known about patients with unilateral or segmentally affected medullary sponge kidney. We report 2 cases of partially affected medullary sponge kidney with normal acidification ability and normal urinary calcium excretion, although the ability to concentrate urine was diminished. These findings suggest that in patients with partially affected medullary sponge kidney nephrolithiasis is not the consequence of renal hypercalciuria induced by systemic acidosis but is owing to the urinary stasis caused by cystic dilatation of the terminal collecting duct.