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Biomedical subjects

Stanley Hellerstein

Publications and source records attributed to Stanley Hellerstein.

11 recordsLinked to original sources
PubMed2006

Acute urinary tract infection--evaluation and treatment.

PURPOSE OF REVIEW: The evaluation and management of urinary tract infections in infants and children is undergoing changes due to the impact of evidence-based studies and new technology. RECENT FINDINGS: The uncircumcised male infant is at increased risk for a urinary tract infection, but there is marked difference in the frequency of circumcision carried out to lower the risk of infection in the United States compared with Europe. Commentaries presenting different interpretations of the current data make for interesting reading and present the many sides of this issue. Vesicoureteric reflux, previously viewed as the major risk factor for acquired renal damage, now shares this role with nonreflux nephropathy. Procalcitonin has been evaluated as a biochemical tool to identify patients at risk for kidney damage, with dimercaptosuccinic acid scintigraphy as the reference method to detect renal scarring. SUMMARY: The previously accepted concept that vesicoureteric reflux as detected radiologically is almost always the key factor in acquired renal injury secondary to a urinary tract infection is no longer accepted. Current studies show that nonreflux nephropathy occurs as often as reflux nephropathy. There is now a question of the value of imaging studies designed to identify vesicoureteric reflux and of the use of suppressive antibiotics for vesicoureteric reflux. There exist useful evidence-based studies for antibiotic therapy for upper and lower tract urinary tract infections, but no such data are available for guidance in selecting imaging studies for the infant or child with a first febrile urinary tract infection.

Acute Disease↗
PubMed2006

Creatinine for evaluation of glomerular filtration rate in children.

This report is to provide primary care physicians with a convenient method for identifying children with impaired kidney function. This is important because of the prevalence of chronic kidney disease in adults and because intervention may delay disease progression. The glomerular filtration rate (GFR) measured using cimetidine clearance and calculated using height and serum creatinine concentration were compared during 222 clearance studies in 32 pediatric patients over 8 years. A child 1 year or older with a calculated GFR<60 mL/min/1.73 m2 has a significantly reduced GFR and should be referred to a pediatric nephrologist for further evaluation.

Adolescent↗
PubMed2005

Timed-urine collections for renal clearance studies.

The purpose of this study was to describe the reproducibility of timed-urine collections for renal clearance studies and the effect variations in urine collection has on measurement of glomerular filtration rate (GFR). Data from 222 cimetidine clearance studies (GFR-Cim) were obtained from 32 pediatric renal patients over a period of 8 years. There were three to 18 studies per child aged 4.8 years to 21 years at the time of a study. The urinary creatinine excretion rate is measured during supervised urine collection periods. The creatinine excretion rates in each child were compared to obtain data on the reproducibility of the urine collections. The coefficient of variation (CV) of the creatinine excretion rate is approximately 10% in both children and adults. The variation in GFR to be expected during repeated renal clearance studies in subjects with stable GFR, using voided urine collections, was similar in children and adults, with a CV of 12% to 14%.

Adolescent↗
PubMed2004

Measurement of renal functional reserve in children.

Renal functional reserve was measured during 89 studies in 78 children as the difference between the baseline glomerular filtration rate (GFR) and that following a protein meal. GFR was measured using creatinine as the filtration marker in children pre-treated with cimetidine. The children had been on a diet free of meat, fish, and fowl for 24 h. The protein meal to stimulate GFR was derived from milk, cheese, eggs, and baked goods. The increase in GFR following the protein meal was due mainly to an increase in the glomerular filtration of creatinine, with a small contribution by decreased serum creatinine concentration. This study confirmed that renal functional reserve can be measured using a meat-free protein meal to stimulate GFR. The protocol employed is a relatively noninvasive and inexpensive procedure for identifying glomerular hyperfiltration in children.

Adolescent↗
PubMed2004

Comparison of two formulae for estimation of glomerular filtration rate in children.

Glomerular filtration rate (GFR) was measured in 216 studies in 151 children using the cimetidine protocol. This was compared with the GFR calculated using Léger's pharmacokinetic equation and with that calculated using k*L/[Cr](s )(constant x length in centimeters divided by serum creatinine concentration). The GFR calculated using the equation GFR=k*L/[Cr](s) yielded a closer approximation to the measured GFR than that using Léger's pharmacokinetic equation. Currently there is focus on screening children for decreased GFR to identify those with asymptomatic chronic kidney disease at a time when intervention may delay progression to chronic renal failure. This study showed close approximation of the calculated GFR with the measured GFR using the equation GFR=k*L/[Cr](s), when the values for k were determined in the laboratory in which creatinine was measured.

Adolescent↗
PubMed2004

The ratio of urinary cystatin C to urinary creatinine for detecting decreased GFR.

Glomerular filtration rate (GFR) and urine and serum concentrations of cystatin C and creatinine were measured in 40 boys and 42 girls. The fractional excretion of cystatin C (FE Cyst C) increased in proportion to the decrease in GFR. Since serum creatinine concentration (S-Creatinine) in the numerator of the fractional excretion equation and serum cystatin C concentration (S-Cystatin C) in the denominator have similar numerical values, they cancel out. The result is an equation in which the FE Cyst C is equal to the ratio of urinary cystatin C to urinary creatinine (u[cystatin-C/Cr]). The ratio of u[cystatin C/Cr] was compared with GFR. Using a receiving operating characteristic (ROC) plot, the data showed that a ratio of u[cystatin C/Cr]*100 that is > or =0.100 has a sensitivity of 90.0% for identification of children with GFR < or =60 ml/min per 1.73 m(2). The false-positive rate is 16.1%. The u[cystatin C/Cr] ratio is a reliable screening tool for detecting decreased GFR that does not require a serum sample.

Adolescent↗
PubMed2002

Prophylactic antibiotics in children at risk for urinary tract infection.

The outcome of using prophylactic antibiotics in children considered at risk for a urinary tract infection (UTI) was documented in 66 children during the period of suppressive antibiotics and for a follow-up period of 3.7+/-2.2 years (range 0.92-9.83 years). A breakthrough UTI occurred in 13 girls but none of the boys during the initial course of prophylactic antibiotics. During the follow-up period, 33 girls and 5 boys had no recurrence of infection, while 25 girls and 3 boys had UTIs. Statistical analysis of the data using chi-square and risk estimate relating factors for infection to the occurrence of a UTI showed that during the period of initial prophylactic antibiotic there was significant risk of infection among children with voiding dysfunction and abnormal kidneys and during the follow-up there was increased risk of infection among those with voiding dysfunction and vesicoureteric reflux (VUR) of grade 3 or greater severity. Lesser grades of VUR and constipation did not significantly increase the risk of UTI. These observations should be useful in developing a study to define the risks and benefits of prophylactic antibiotic in "at-risk" children.

Anti-Bacterial Agents↗
PubMedDate not supplied

Voiding dysfunction in pediatric patients.

The goals of this study were to describe the pattern of voiding disorders in children in our community, to describe clinical criteria for making the specific diagnoses, and to comment on management. The medical records of 226 children referred because of voiding dysfunction or urinary tract infections (UTI) were evaluated. Children with normal voiding patterns when uninfected, with monosymptomatic nocturnal enuresis, and with known neurologic or anatomic abnormalities were excluded. Detrusor instability, an abnormal voiding pattern characterized by urgency with or without frequency, was the diagnosis in 175 of the 226 children. Children with detrusor instability who used various posturing maneuvers to avoid urinary incontinence had a significantly higher incidence of UTIs than those who did not attempt to obstruct urine outflow. Detrusor instability appeared to be secondary to constipation in 19 of the children. The other diagnoses were extraordinary daytime urinary frequency, infrequent voiding, monosymptomatic daytime wetting, transient voiding dysfunction, giggle incontinence, dysfunctional voiding, and unexplained dysuria. It is concluded that children with detrusor instability who use posturing maneuvers to avoid incontinence are at high risk for recurrent UTIs. Constipation is 1 cause of detrusor instability. Dysfunctional voiding, the form of voiding dysfunction most likely to result in renal damage, was present in only 2 of 226 children seen for voiding disorders.

Age Distribution↗
PubMedDate not supplied

Outcome of overactive bladder in children.

One hundred forty-four children with a clinical diagnosis of overactive bladder were observed for a mean of 3.15 +/- 1.92 years. Initial management consisted of a behavioral modification program that included increased fluid intake, a timed voiding schedule and, if applicable, treatment of constipation. Those who failed to improve with the preceding intervention within 10 days to 2 weeks received an anticholinergic medication. Follow-up information was obtained by telephone. Caretakers and/or patients were asked a standard set of questions. The outcome with respect to urinary urgency, urinary frequency, daytime incontinence, posturing and urinary tract infections was recorded. After an average follow-up period of 3 years, 68 (47.2%) of the 144 children recovered from all symptoms of overactive bladder and 61 (42.4%) had decreased symptoms. Fifteen of the children, or 10.4%, still had all of the symptoms originally associated with overactive bladder. Children who had posturing as one of their symptoms had a significantly increased risk of urinary tract infection.

Behavior Therapy↗