Renal function during hydropenia and water diuresis in children with recurrent urinary tract infections

Decreased concentrating capacity in children with febrile urinary tract infection and normal 99mTc-dimercaptosuccinic acid scan: does medullonephritis exist?

BACKGROUND

Although 99mTc-dimercaptosuccinic acid (DMSA) scan is considered the gold standard for the diagnosis of acute pyelonephritis (AP), sometimes it produces false results in children with clinical features of AP. There are no studies on the comparison of the sensitivity of DMSA and concentrating capacity test.

METHODS

Eighty-five infants with AP of less than one year old were studied to evaluate whether they had real AP or not. Data were compared between infants with an abnormal (group A, n=64) and those with a normal DMSA scan (group B, n=21) respectively. A DDAVP test was performed for each infant.

RESULTS

All the infants in both groups presented a high level of C-reactive protein and fever (≥38°C). There were no differences in clinical and analytical variables except C-reactive protein level in the two groups. Both groups exhibited a low urinary osmolality (87.5% in the group A vs. 85.7% in the group B). The patients with normal DMSA and decreased concentrating capacity have some renal parenchymal damage and not only a lower urinary infection. Of the infants with an abnormal DMSA scan, 33.9% showed renal scars after 6-12 months. No infant with a normal DMSA scan showed scars. The biochemical variables in both groups of infants were not related to vesicoureteral refl ux.

CONCLUSION

Infants with AP, normal DMSA scan and low concentrating capacity may be characterized by a localized infection in the medulla (medullonephritis) or by a false negative DMSA scan.

Pediatric urinary tract infection: does the evidence support aggressively pursuing the diagnosis?

The epidemiology of pediatric fever has changed considerably during the past 2 decades with the development of vaccines against the most common bacterial pathogens causing bacteremia and meningitis. The decreasing incidence of these 2 conditions among vaccinated children has led to an emphasis on urinary tract infection as a remaining source of potentially hidden infections in febrile children. Emerging literature, however, has led to questions about both the degree and nature of the danger posed by urinary tract infection in nonverbal children, whereas the aggressive pursuit of the diagnosis consumes resources and leads to patient discomfort, medical risks, and potential overdiagnosis. We review both early and emerging literature to examine the utility and efficacy of early identification and treatment of urinary tract infection in children younger than 24 months. We conclude that in well children of this age, it may be reasonable to withhold or delay testing for urinary tract infection if signs of other sources are apparent or if the fever has been present for fewer than 4 to 5 days.

Renal dysfunction in recurrent urinary tract infections in childhood

One hundred children aged 1.5-19.5 years, with recurrent urinary tract infections, at least one of which was febrile (pyelonephritis, PN), were investigated by means of inulin and para-aminohippurate (PAH) clearance tests for the evaluation of glomerular filtration rate (GFR), effective renal plasma flow, and concentrating and diluting capacities. Renal function data were collated with the clinical history and radiological findings. GFR and PAH clearance were found to be reduced compared with controls. Patients whose first PN was diagnosed before the age of 3--particularly those with a history of three or more PN infections--showed the lowest values for GFR and PAH clearance. Furthermore, parenchymally reduced kidneys were found most frequently in this group of patients. Concentrating capacity was decreased in some patients, but a low concentrating capacity did not reveal patients with reduced GFRs. Diluting capacity evaluated as minimal urine osmolality was normal, but was reduced when evaluated as free water clearance in some patients with reduced values for GFR.

Age as a main determinant of renal functional damage in urinary tract infection

Renal function was studied in 61 girls suffering from recurrent urinary tract infections, with at least one febrile infection. Clearance of inulin was determined. Intravenous urography and micturating cystourethrography were performed 1-6 months after the first infection and 0-6 months before or after the function test. A low glomerular filtration rate (GFR) was found only among children with their first pyelonephritis before the age of 3 years. A low GFR was found mostly in patients with small or scarred kidneys but was also seen in a few patients with normal intravenous urographs. Low GFR as well as radiologically small kidneys at the time of the function test were found independently of the presence or grade of vesicoureteral reflux at first infection. Patients with early onset pyelonephritis (before age 3 years) had a low capacity for early compensatory hypertrophy in contrast to patients with late onset pyelonephritis.

Relationship between area and function of the kidney in well defined childhood nephropathies

Length, parenchymal area planimetrically determined and volume of the kidney were estimated at urography and related to glomerular filtration rate in patients with different nephropathies. The results demonstrate that the size of the kidney is an excellent index of renal function in patients with pyelonephritic scarring secondary to urinary tract infection and vesicoureteral reflux. It is also a good index in patients with obstructive hydronephrosis but a poor index in patients with glomerulonephritis.