First Reported Case of a Pyrophosphate Kidney Stone in a Human.

Urolithiasis composed of pyrophosphate salts has only been reported in animals, in the form of potassium magnesium pyrophosphate. However, there have been no reports of pyrophosphate stones in humans. Hypophosphatasia is an inherited disease characterized by low alkaline phosphatase activity and elevated levels of pyrophosphate in blood and urine. Urolithiasis is a part of the hypophosphatasia phenotype. The role of elevated urine pyrophosphate levels in the formation of stones in hypophosphatasia is unknown. Here, we report a case of a 60-year-old man with recurrent urolithiasis. The patient's most recent presentation was gross hematuria and his computed tomography scan showed bilateral kidney stones. Stones were removed via retrograde intrarenal surgery. Stone analysis revealed a composition of potassium magnesium pyrophosphate. The patient also has a long history of fracturing bone disease which led to the consideration of hypophosphatasia as the cause of both his bone disease and pyrophosphate stones. Hypophosphatasia was confirmed by genetic analysis. Pyrophosphate has been of interest in the fields of mineral metabolism because of its action as a crystallization inhibitor. However, pyrophosphate at elevated concentrations in the presence of divalent cations can exceed its solubility. Nephrocalcinosis and stone disease have been described in hypophosphatasia; stones have been assumed to be calcium phosphate but no compositional analysis has been reported. This is the first report of human stones composed of pyrophosphate salts, which led to the subsequent diagnosis of hypophosphatasia in this patient.

Nocturnal bladder emptying: a simple technique for reversing urinary tract deterioration in children with neurogenic bladder.

PURPOSE: In this preliminary study we sought to determine the effect of instituting nocturnal bladder emptying (NBE) in children with neurogenic (NGB) or nonneurogenic neurogenic bladder (NNGNGB) in whom urinary tract deterioration developed despite optimal daytime clean intermittent catheterization (CIC) and urotropic medications. We hypothesize that a syndrome of nocturnal overdistention of the bladder (SNOB) can cause urinary tract deterioration through increased nighttime storage pressures manifested by recurrent urinary tract infection (UTI), worsening incontinence, hydronephrosis and/or decreasing bladder compliance and capacity, and may be reversed by NBE. MATERIALS AND METHODS: A total of 19 children with NGB (17) or NNGNGB (2) who displayed urinary tract deterioration while on CIC and urotropic medications were started on NBE. Of the patients 15 used a continuously draining nighttime catheter while 4 had scheduled awakenings during the night to perform CIC. The primary indications for NBE were recurrent symptomatic UTI in 5, new or progressive hydronephrosis in 7, and decreasing bladder capacity and compliance in 7. RESULTS: At a mean followup of 23 months 15 (79%) patients showed improvement or complete resolution of 1 or more signs or symptoms of hydronephrosis (7), increase in bladder capacity (5), recurrent UTI (6) and worsening incontinence (3). The remaining 4 patients had no response to NBE. No adverse effects were observed with 10 hours or less of nightly indwelling catheter time. CONCLUSIONS: Patients with NGB or NNGNGB on idealized daytime programs of CIC and urotropic drugs may have high intravesical pressures and experience urological deterioration because of an unrecognized SNOB. NBE is a simple technique for treating this condition and reversing the pathophysiological changes. The observation that NBE alone may increase bladder compliance and capacity sufficient to avoid bladder augmentation suggests that development of decreased bladder compliance and capacity in children with NGB may not simply represent normal progression of NGB disease. These changes may be avoidable consequences of untreated SNOB. Early institution of NBE may prevent urinary tract deterioration from developing in this population.