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Biomedical subjects

U Alon

Publications and source records attributed to U Alon.

At least 19 recordsLinked to original sources
PubMed1992

Creatinine for estimation of glomerular filtration rate.

The aim of this study was to evaluate the plasma creatinine concentration (PCr) and creatinine clearance (CCr) for estimation of glomerular filtration rate (GFR). Inulin clearance (Cin) was used as the reference standard for GFR. Thirty-nine concurrent Cin and CCr studies provided data for comparing Cin with the measured CCr and with the calculated CCr (calc-CCr). (Calc-CCr = k.L/PCr, where L = height in centimeters and k is the proportionality constant.) Thirty-one children 5.3-20.8 years of age, with Cin ranging from 2.8 to 138.8 ml/min per 1.73 m2, participated in these studies at The Children's Mercy Hospital. The measured CCr was 16.7 +/- 10.3 ml/min per 1.73 m2 (P < 0.001) greater than the Cin, and the calc-CCr overestimated Cin by a mean of 31.6 +/- 20.8 ml/min per 1.73 m2 (P < 0.001). Although there is good correlation between Cin and CCr (r = 0.96), and Cin and calc-CCr (r = 0.90), the 95% confidence intervals are quite broad. Hence, the CCr and the calc-CCr, derived using Schwartz values for k, consistently overestimate GFR. However, if the k value in the equation GFR = k.L/PCr is derived from k = Cin/L, rather than from k = CCr.PCr/L, a more accurate estimate of GFR may be obtained.

Adolescent↗
PubMed1992

Metabolic and histologic investigation of the nature of nephrocalcinosis in children with hypophosphatemic rickets and in the Hyp mouse.

To investigate the biochemical nature of nephrocalcinosis in children with hypophosphatemic rickets treated with orally administered phosphate and vitamin D, we studied five such patients, aged 3.7 to 12.3 years, during treatment and again 3 days after it had been discontinued. Treatment was associated with significant increases in mean serum phosphate concentration and urine phosphate/creatinine ratio, from 0.71 to 1.03 mmol/L and from 3.61 to 9.42 mmol/mmol, respectively. Significant correlation was found between urine phosphate/creatinine and oxalate/creatinine ratios (r = 0.670; p less than 0.01); however, the mean urine oxalate/creatinine ratio of 65.0 mumol/mmol while patients were taking phosphate orally was not significantly different from the ratio of 59.0 mumol/mmol when treatment was discontinued. Kidney biopsy specimens from three of the patients showed that the renal calcifications were located mainly intratubularly and were composed exclusively of calcium phosphate. In a further investigation of the nature of phosphate-induced nephrocalcinosis, six 6-week-old male Hyp mice, the murine analog of the human disease, received oral phosphate therapy with drinking water for 48 days; six others served as control animals. Mice in the experimental group excreted more phosphate (p less than 0.001) and less calcium (p less than 0.01) than control mice did, and medullary nephrocalcinosis, with a high kidney calcium content, developed (p less than 0.001). Histologic sections showed that the renal calcifications were located intratubularly and were composed of calcium phosphate. We conclude that, both in children with hypophosphatemic rickets and in the Hyp mouse, the development of nephrocalcinosis is associated with high oral phosphate intake and subsequent deposition of calcium phosphate precipitates in the kidney.

Animals↗
PubMed1992

Kidney function in very low birth weight infants with furosemide-related renal calcifications at ages 1 to 2 years.

To determine whether long-term renal sequelae follow the use of furosemide in preterm infants, we evaluated renal function in 27 former very low birth weight infants (less than 1500 gm) at 1 to 2 years of age. Patients were classified into three groups on the basis of status at the time of discharge from the hospital: group 1 (n = 7) had no furosemide treatment or renal calcifications, group 2 (n = 10) had furosemide therapy but no calcifications, and group 3 (n = 10) had furosemide therapy with renal calcifications. Renal ultrasonography at the time of the study demonstrated resolution of the calcifications in six patients in group 3. No differences in renal function were observed between groups 1 and 2. Creatinine clearance (mean +/- SEM) in group 3 (83.6 +/- 7.8 ml/min per 1.73 m2) was significantly lower than clearance in groups 1 and 2 (103.2 +/- 6.5 and 109.1 +/- 5.1, respectively; p less than 0.05). Children in group 3 had significantly higher urinary calcium/creatinine ratios and fractional excretion of sodium and lower tubular reabsorption of phosphate than children in the two other groups had. Urine-blood difference in carbon dioxide tension after oral acetazolamide load, which indicates the ability of the distal tubule to secrete hydrogen ions, was 8.4 +/- 3.4 mm Hg in group 3, significantly lower than values in groups 1 and 2 (22.6 +/- 3.1 and 28.0 +/- 4.3 mm Hg, respectively, p less than 0.05). Within group 3 the four children with persistent renal calcifications had significantly lower urine-blood carbon dioxide tension differences than did those with resolution of calcifications (p = 0.02). We conclude that furosemide-related renal calcifications in very low birth weight infants may lead to glomerular and tubular dysfunction; further long-term follow-up of this population is recommended.

Absorption↗
PubMed1992

Residential summer camp for children with end-stage renal disease.

Residential summer camps exist for children with all varieties of chronic illness with the goal of improving their quality of life. This paper describes the development and implementation of a summer camp for children 9-18 years old who receive long-term peritoneal dialysis or who have received a kidney transplant. Thirty-five to forty children regularly participate in activities such as water olympics, survival hikes and campouts while continuing to receive their medical needs from trained personnel. A study to evaluate the impact of a summer camp revealed less patient hopelessness and improved self-esteem following the 1-week camping experience. Attendance at camp provided the medical staff with a unique perspective of childhood illness, while the period of respite for the parents was uniformly welcomed and may contribute to the prevention of parent burnout. It is hoped that the success of this camp and others like it will lead to the development of similar experiences for other children with chronic disease.

Adolescent↗
PubMed1992

Idiopathic infantile hypercalcemia: rapid response to treatment with calcitonin.

We report on a 7-week-old infant with idiopathic hypercalcemia, hypercalciuria and nephrocalcinosis. At the time of admission, serum concentrations of parathyroid hormone and 1,25(OH)2D3 were found to be inadequately high, and those of calcitonin and 24,25(OH)2D3 too low, relative to the hypercalcemia. Treatment with calcitonin normalized serum calcium concentrations within 4 days, and a 3-week course of thiazides combined with a decreased dietary calcium:phosphorus ratio corrected the hypercalciuria. A repeat profile of the calcium-regulating hormones done at the age of 5.5 months was normal. Based on the clinical course and the hormonal profiles, we hypothesize that the idiopathic infantile hypercalcemia in this patient could have resulted from a generalized maturational delay of calcium homeostasis. Treatment with calcitonin, therefore, seems to be the most appropriate way to control the hypercalcemia.

24,25-Dihydroxyvitamin D 3↗
PubMed1991

Recombinant human erythropoietin therapy in pediatric patients receiving long-term peritoneal dialysis.

We evaluated the impact of (s.c.) recombinant human erythropoietin (r-HuEPO) therapy on the hematological status, exercise capacity, and dietary intake of nine pediatric patients (mean age 12.4 +/- 3.2 years) receiving long-term peritoneal dialysis. Five children without medical illness served as controls for the exercise testing portion of the study. Following 7.9 +/- 2.8 weeks of twice weekly r-HuEPO (50 units/kg per dose), the hematocrit increased from 21.9 +/- 3.5% to 31.3 +/- 2.5% (P less than 0.001). A further increase to 33.2 +/- 3.0% occurred after 2 months of once weekly therapy. The blood transfusion requirement decreased from 0.5 transfusions per patient-month to 0.05 transfusions per patient-month (P less than 0.01). Graded exercise testing demonstrated an increase in peak oxygen consumption from 17.8 +/- 5.2 to 24.0 +/- 7.6 ml/kg per min (P less than 0.01). The oxygen consumption at anaerobic threshold increased from 13.1 +/- 3.9 to 17.1 +/- 3.5 ml/kg per min (P less than 0.02). Treadmill time increased from 5.3 +/- 1.2 to 7.5 +/- 1.3 min (P less than 0.001). In each case, the percentage improvement was significantly greater than the improvement seen in the control population. Dietary evaluation revealed no significant change in caloric or protein intake, despite a subjectively improved appetite. r-HuEPO, given by the s.c. route, corrects the anemia and improves the exercise capacity of pediatric patients receiving long-term peritoneal dialysis.

Adolescent↗
PubMed1991

Oral acetazolamide in the assessment of (urine-blood) PCO2.

Urine-blood (U-B)Pco2 difference in children is usually assessed following urine alkalinization with oral sodium bicarbonate (NaHCO3). Since oral NaHCO3 is often poorly tolerated by children, we compared oral acetazolamide with oral NaHCO3 in a study of (U-B)Pco2. In the first phase of the study 14 children and adolescents aged 11.1 +/- 3.7 years (mean +/- SD) were studied. Eight participants had normal kidney function and 6 had disturbed distal acidification capacity. Each child was studied twice, once with oral NaHCO3 (2.5 mEq/kg) and once with acetazolamide (17 +/- 2 mg/kg). All studies were performed according to the standard protocol. Acetazolamide administration resulted in a lower blood pH than NaHCO3 (7.30 +/- 0.03 vs 7.38 +/- 0.06, P less than 0.001) and a lower serum bicarbonate (HCO3-) concentration (25.1 +/- 2.2 mEq/l vs 27.5 +/- 2.1 mEq/l, P less than 0.025). Acetazolamide also resulted in a higher urine Pco2 (81.9 +/- 26.2 mm Hg vs 71.6 +/- 18.2 mm Hg) than NaHCO3 (P less than 0.025). No significant differences between acetazolamide and NaHCO3 were observed with respect to their effects on urinary pH and HCO3- concentration, plasma Pco2 and (U-B)Pco2. Good linear correlations were found between the effects of acetazolamide and NaHCO3 on urine Pco2 (r = 0.878, P less than 0.001), and on (U-B)Pco2 (r = 0.795, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetazolamide↗
PubMed1991

Furosemide-related renal calcifications in the premature infant. A longitudinal ultrasonographic study.

Low birthweight infants treated with chronic furosemide therapy are at risk for the development of intrarenal calcifications. A prospective longitudinal renal ultrasound investigation was conducted to study the correlation of diuretic therapy, clinical course and ultrasonographic findings. Of 117 premature infants studied ultrasonographically upon discharge from the hospital, 20 had intrarenal calcifications. Eight patients at age 16.3 +/- 2.6 months had sonographic resolution of renal calcifications, 6.6 +/- 1.1 months after furosemide therapy had been discontinued. Of the 12 patients with persistent calcifications, 4 died from severe pulmonary disease and autopsy in 3 of them confirmed the ultrasonographic diagnosis. All 12 children but 2 continued to receive furosemide for their chronic lung disease demonstrating significant association between chronic use of loop diuretics and persistence fo the renal calcifications (p less than 0.001). Two patients required nephrolithotomy and 4 suffered from recurrent urinary tract infections. In 4 patients, 5 kidneys were of small size and in 2 bilateral collecting system dilation was noted. We conclude that discontinuation of furosemide therapy is associated with resolution of the renal calcifications. On the other hand, continued treatment with furosemide is associated with high renal morbidity which indicates ongoing clinical and ultrasonographic follow-up.

Child, Preschool↗
PubMed1991

Primary nocturnal enuresis: current concepts about an old problem.

In summary, all children and families who present with nocturnal enuresis should be offered education, reassurance, and ongoing support as a premier component of any treatment regimen. At the same time, the family should be informed about all the treatment options that exist with a goal of tailoring the specific treatment to the individual patient. In most cases, this approach will lead to child, family, and physician satisfaction.

Behavior Therapy↗
PubMed1990

The value of ultrasound in Schoenlein-Henoch purpura.

We report the results of ultrasound studies on 11 children with Schoenlein-Henoch purpura. In 8 children the ultrasound examination was normal. In two of three patients with macroscopic haematuria, haemorrhagic cystitis, a previously undescribed finding in Schoenlein-Henoch purpura, was found. In one case the gall bladder wall and the wall of several adjacent loops of bowel were markedly thickened. Follow up examinations after clinical recovery demonstrated complete resolution of these abnormalities. Our observations demonstrate that diagnostic ultrasound may have an important role before more expensive and invasive procedures are employed in patients with Schoenlein-Henoch purpura.

Child↗