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SummaryChildren with refractory epilepsy who are co-treated with the ketogenic diet (KD) and carbonic anhydrase inhibitor (CA-I) anti-epileptic medications including topiramate (TPM) and zonisamide (ZNS) are at risk for urolithiasis. Retrospective chart review of all children treated with ketogenic therapy at our institution was performed in order to estimate the minimal risk of developing signs or symptoms of stone disease. Children (N = 93) were classified into groups according to KD +/− CA-I co-therapy. Fourteen patients had occult hematuria or worse, including 6 with radiologically confirmed stones. Three of 6 calculi developed in the KD + ZNS group of 17 patients who were co-treated for a cumulative total of 97 months (3.1 stones per 100 patient months). One confirmed stone was in the KD + TPM group of 22 children who were co-treated for a cumulative total of 263 months (0.4 stones per 100 patient months). All six patients had at least three of five biochemical risk factors including metabolic acidosis, concentrated urine, acid urine, hypercalciuria and hypocitraturia. Standard of care interventions to minimize hypercalciuria, crystalluria and stone formation used routinely by pediatric nephrologists should also be prescribed by neurologists treating patients with combination anti-epileptic therapy. Non-fasting KD initiation, fluid liberalization, potassium citrate prophylaxis as well as regular laboratory surveillance are indicated in this high risk population.

Rabbit proximal straight tubules swell abruptly when exposed to hypotonic medium but then shrink in a few minutes as they approach their base-line volume following loss of solute and water. Potassium, the major intracellular cation, as well as sodium, is lost during this process. In the present experiments, we studied hypotonic cell volume regulation in the presence of barium, an agent reported to decrease potassium permeability. Exposure to BaCl2 significantly prolonged hypotonic volume recovery in a dose-dependent manner. Tubules depleted of potassium and loaded with sodium chloride by exposure to 10(-4) M ouabain for 1 h swelled osmometrically and subsequently volume regulated in dilute medium. Volume regulation in such tubules is a consequence of transbasement membrane hydrostatic forces. By contrast, tubules similarly loaded with sodium, but also exposed to 10(-3) M BaCl2, volume regulated only minimally in dilute medium, suggesting BaCl2 might also affect sodium movement. However, hypotonic volume regulation was restored in sodium-loaded BaCl2-treated tubules when cells were more effectively depleted of potassium by incubation in 0-mM potassium medium. We conclude that barium retards hypotonic volume regulation primarily because of its effect on potassium movement.

Management of childhood urinary tract infections is conceptually straightforward, but controversies persist. Specimens must be collected carefully or culture results can be difficult to interpret. Urine culture remains the diagnostic standard but does not substitute for careful urinalysis. Radiography studies are designed to define abnormalities predisposing patients to pyelonephritis and to assess the extent of renal involvement during infection, but there is no agreement on the most appropriate combination of studies. Circumcision reduces the incidence of urinary infections in male infants. Vaginal reflux may have an impact on recurrent infections, especially after courses of antibiotics. The importance of vesicoureteral reflux remains controversial because renal scarring appears to be related more to infection than to reflux itself. A strong argument can be made for the avoidance of prophylactic antibiotic therapy, even in patients with reflux. Increased attention to early diagnosis and treatment may be responsible for a decreasing incidence in renal failure from reflux nephropathy in children.

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