Diagnostic yield of parathyroid hormone testing in children evaluated for hypercalciuria.

Hypercalciuria is a frequent cause of non-glomerular hematuria in pediatric patients. Because hypercalciuria can be secondary to primary hyperparathyroidism, measurement of serum parathyroid hormone (PTH) levels is often performed in children with this urinary abnormality. A retrospective chart review was performed to determine the diagnostic yield of PTH measurements when performed under these clinical circumstances. Over a 30-month period (January 1, 2001 to September 30, 2003), among 31 children who had a PTH determination, the level was elevated in 1 (3%) patient. Based on these findings and the serious nature of untreated primary hyperparathyroidism, serum PTH level should be measured in pediatric patients with newly diagnosed hypercalciuria.

Glomerular permeability activity: prevalence and prognostic value in pediatric patients with idiopathic nephrotic syndrome.

BACKGROUND: A circulating factor that increases in vitro glomerular permeability to albumin (P alb ) has been isolated from patients with recurrence of focal segmental glomerulosclerosis in their renal allografts. The prevalence and prognostic significance of permeability activity has not been examined in children with idiopathic nephrotic syndrome (INS). METHODS: P alb activity level was determined in sera from 26 children with new-onset INS before the initiation of therapy by using an in vitro assay. Permeability factor was considered present if P alb was greater than 0.5. The following clinical and laboratory data for patients were tabulated: demographic information, serum albumin and cholesterol concentrations, calculated glomerular filtration rate, age at disease onset, response to corticosteroid treatment, and long-term outcome. RESULTS: Patients ranged in age from 2 to 18 years, and 19 patients (73%) were male. Mean P alb was 0.45 +/- 0.04 (SEM). P alb in patients with a steroid-responsive course (n = 17) did not differ from that of patients with steroid-resistant disease (n = 9). Percentages with P alb greater than 0.5 did not differ between patients with steroid-responsive and steroid-resistant disease (47% and 33%, respectively). P alb was determined after 41 +/- 5 months in 6 patients with steroid-responsive INS. These patients had normal serum creatinine concentrations, and 4 of 6 patients were in prolonged remission. P alb at the onset of INS before therapy was 0.51 +/- 0.09 (P alb > 0.5 in 2 patients) and was not changed at follow-up (P alb = 0.40 +/- 0.12; P alb > 0.5 in 2 patients). CONCLUSION: Permeability activity, defined as P alb greater than 0.5, is present in pretreatment serum samples from nearly half the children with INS. The presence of permeability activity does not predict clinical response to steroid treatment, renal histopathologic characteristics, or clinical outcome at up to 5 years of follow-up.

Angiotensin converting enzyme inhibitor therapy in children with Alport syndrome: effect on urinary albumin, TGF-beta, and nitrite excretion.

BACKGROUND: Angiotensin converting enzyme inhibitors are routinely prescribed to patients with chronic kidney disease because of their known renoprotective effects. We evaluated the effect of short-term therapy with the angiotensin converting enzyme inhibitor, enalapril, in early Alport syndrome, defined as disease duration less than 10 years and a normal glomerular filtration rate. METHODS: 11 children with early Alport syndrome were investigated. Two consecutive early morning urine specimens were collected at the start of the study for measurement of urinary creatinine, total protein, albumin, TGF-beta, and nitrite excretion. Patients were treated with enalapril, congruent with 0.2 mg/kg/day, once a day for 14 days. Two early morning urine specimens were collected on days 13 and 14 of enalapril treatment and two weeks later for measurement of urinary creatinine, total protein, albumin, TGF-beta, and nitrite excretion. RESULTS: Prior to treatment, urinary excretion of transforming growth factor-beta and nitrite, the major metabolite of nitric oxide, was within normal limits in all patients. Administration of enalapril for 2 weeks did not alter urinary albumin, transforming growth factor-beta, or nitrite excretion. CONCLUSION: These findings suggest that early Alport syndrome represents a disease involving exclusively intrinsic glomerular barrier dysfunction. At this stage of the illness, there is no evidence of angiotensin II-mediated proteinuria or increased production of transforming growth factor-beta and, therefore, routine treatment with an angiotensin converting enzyme inhibitor may not be warranted.