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Biomedical subjects

U S Alon

Publications and source records attributed to U S Alon.

At least 19 recordsLinked to original sources
PubMed2001

Synaptopodin expression in idiopathic nephrotic syndrome of childhood.

BACKGROUND: Synaptopodin is a proline-rich protein intimately associated with actin microfilaments present in the podocytes' foot processes. We investigated for synaptopodin expression in children with idiopathic nephrotic syndrome (INS), including minimal change disease (MCD), diffuse mesangial hypercellularity (DMH), and focal segmental glomerulosclerosis (FSGS); in children with congenital nephrotic syndrome of the Finnish type (CNF); and in normal kidney tissue. In particular, we examined whether an association exists between synaptopodin expression in podocyte cells and the response to steroids in INS, and whether synaptopodin expression can predict FSGS upon the initial kidney biopsy in children who progress from MCD or DMH to FSGS. METHODS: Immunohistochemistry was performed for synaptopodin expression on renal tissues from MCD (N = 18), DMH (N = 7), FSGS (N = 13), CNF (N = 9), and normal children (N = 7). Synaptopodin expression in nonsclerosed glomeruli was quantitated by computerized image analysis on the Optimastrade mark software for both luminance (L) and percentage of glomerular area (A). RESULTS: Synaptopodin expression was absent in areas of sclerosis. In nonsclerosed glomeruli, synaptopodin was significantly less expressed in all groups of INS and in CNF compared with normal (P < 0.0001 for both L and A, in each MCD, DMH, FSGS, and CNF). In INS, synaptopodin expression decreased in order from MCD to DMH to FSGS, reaching statistical significance between MCD and FSGS (P = 0.001 for L and P = 0.05 for A). Greater synaptopodin expression in podocytes was associated with a significantly better response to steroid therapy (P < 0.05 for both L and A). On the other hand, the expression of synaptopodin did not predict progression of MCD or DMH to FSGS. CONCLUSION: We conclude that measurement of synaptopodin has the potential to be used as a marker to study the alteration in podocyte cell and response to therapy in INS.

Child↗
PubMed2000

Success and safety of same-day kidney biopsy in children and adolescents.

Renal biopsy is crucial for the diagnosis, management, and monitoring of many kidney diseases. Although percutaneous renal biopsy is considered a routine safe procedure in children, the optimal length of in-hospital observation following the procedure is not yet known. We prospectively studied two comparable groups of children to compare the success and safety of performing native renal biopsy as an outpatient procedure versus keeping the children hospitalized post biopsy. Doppler ultrasonography of the biopsied kidney was performed approximately 2 weeks after the procedure. For 40 children the biopsy was performed on a same-day basis (study group) and another 15 children were kept for overnight observation (control group). All biopsies yielded adequate tissue for histopathological diagnosis. There was no difference between the two groups in the amount of reported pain and analgesics used after the procedure. Only 1 child in the study group was readmitted 5 days after the biopsy for 48 h, but no major complications were detected. The incidence of post-biopsy intra- or perirenal hematoma detection by sonography was not statistically different between the two groups (39% study group, 43% control group). Follow-up imaging studies were performed on 10 of the 20 children who had an early post-biopsy hematoma and all were completely normal. Patients and their families appreciated being discharged home the same day. In addition, total charges for hospitalization were significantly less for the study group than the control group. We conclude that in selected patients, same-day discharge after renal biopsy may be performed safely without an increased risk of complications.

Adolescent↗
PubMed2000

Pediatric biopsy of a single native kidney.

Technological improvements have reduced the frequency of complications in children receiving a percutaneous renal biopsy. No study has systematically compared the safety of open and percutaneous kidney biopsy. Yet many nephrologists consider a single native kidney an absolute contraindication to percutaneous biopsy. We have established an international registry of single native kidney biopsies in children and we now report our early results. Eight biopsies are included. Seven patients had percutaneous biopsies and one an open biopsy. None of the patients had major complications, and adequate tissue was obtained from all. Our limited experience indicates that the presence of a single native kidney is not an absolute indication for an open approach. We encourage our colleagues to report to the international registry in order to further document the safety of percutaneous biopsy of the single native kidney in children.

Acute Kidney Injury↗
PubMed2000

Sieving coefficient inaccuracies during hemodiafiltration in patients with hyperbilirubinemia.

Hemodiafiltration has assumed an important role in the supportive therapy of critically ill patients. The viability of the filter used for hemodiafiltration can be monitored by estimating the sieving coefficient of small molecules such as creatinine and/or urea. We report on three patients with severe hyperbilirubinemia whose creatinine sieving coefficient was spuriously elevated as a result of discordance in the accuracy of creatinine measurement in plasma and ultrafiltrate respectively. This discordance was a consequence of lack of bilirubin clearance during hemodiafiltration. As a result, while the plasma creatinine determination by the kinetic Jaffe method was negatively influenced by the hyperbilirubinemia, the ultrafiltrate creatinine was not. This report is the first to document the lack of bilirubin clearance during hemodiafiltration and its impact on the calculation of sieving coefficient based on creatinine. The use of urea as the solute for determining the sieving coefficient allows for an accurate estimate and provides a valid means of monitoring this parameter in the setting of hyperbilirubinemia.

Bilirubin↗
PubMed2000

Effect of thiazide on established furosemide-induced nephrocalcinosis in the young rat.

A previous study on furosemide-induced nephrocalcinosis (NC) showed only partial resolution of the calcifications after discontinuation of the diuretic. We investigated whether treatment with chlorothiazide (CTZ) will expedite the resolution of established furosemide-induced NC. Seventy-eight weanling male Sprague-Dawley rats were divided into eight groups. Three groups were studied for 1 week: A, control; B, furosemide 40 mg/kg per 24 h; C, CTZ 100 mg/kg per 24 h. Five groups were studied for 5 weeks: D, control; E, F, G, furosemide 40 mg/kg per 24 h for 1 week followed by 4 weeks of observation (E), CTZ 50 mg/kg per 24 h (F), and CTZ 100 mg/kg per 24 h (G) and; and CTZ 100 mg/kg per 24 h (H) for 5 weeks. At the end of each study period urine and blood were collected, one kidney was studied histologically and the contralateral ashed for quantitative calcium (Ca) analysis. Animals in group B developed NC with a kidney Ca content of 1,844 +/- 203 micrograms/g dry tissue compared with group A 248 +/- 86 (P < 0.05) and group C 256 +/- 56 (P < 0.05). There were no differences among the three groups with regard to creatinine clearance, urine phosphate (P) or Ca excretion, although the latter tended to be lower in group C. Animals in group E showed a reduction in the magnitude of NC, with kidney Ca of 550 +/- 398 micrograms/g dry tissue, which was lower than in group B (P < 0.05) but still higher than in groups D (140 +/- 27) (P < 0.05) or H (162 +/- 63) (P < 0.05). Kidney Ca content in groups F (497 +/- 142) and G (489 +/- 271 micrograms/g dry tissue) was similar to that in group E. There were no differences among the five groups with regard to creatinine clearance or urine P excretion. Urine Ca excretion was significantly lower in groups F and G than groups D and E. We conclude that once established, NC caused by furosemide is not affected by CTZ therapy in spite of the anticalciuric property of the latter.

Animals↗
PubMed2000

C1q nephropathy presenting as rapidly progressive crescentic glomerulonephritis.

C1q nephropathy is an immune complex glomerulonephritis defined by the presence of mesangial immunoglobulins and complement deposits, most notably C1q, and the absence of clinical and laboratory evidence of systemic lupus erythematosus. Histology in C1q nephropathy is characterized by a slight to severe increase in mesangial cellularity and matrix, with or without segmental sclerosis. C1q nephropathy usually presents with nephrotic-range proteinuria in older children and young adults, and has a poor response to steroids. Patients may have decreased creatinine clearance at presentation, but progression to end-stage renal disease (ESRD) is slow. Severe crescentic glomerulonephritis has not been reported in C1q nephropathy. We describe a 3-year-old Hispanic girl who presented with renal insufficiency. Kidney biopsy showed C1q nephropathy with severe crescentic glomerulonephritis. The clinical and serological evaluation ruled out systemic lupus erythematosus or other immunological or infectious etiologies. In spite of immunosuppressive therapy, she progressed to ESRD within 14 weeks and is currently on chronic peritoneal dialysis. The atypical features of C1q nephropathy observed in our patient, which have not been described in earlier reports, are an early age of onset, severe crescentic glomerulonephritis, and rapid progression to ESRD. C1q nephropathy should be added to the differential diagnosis of glomerulonephritis in young children and in the patient with crescentic glomerulonephritis.

Antigen-Antibody Complex↗
PubMed2000

Idiopathic hypercalciuria of childhood: 4- to 11-year outcome.

Apart from a minority with urolithiasis, the majority of children diagnosed with idiopathic hypercalciuria present with macro- or microhematuria, abdominal or back pain, or voiding symptoms. With dietary and pharmacological interventions, most such children become asymptomatic and are lost to follow-up, hence their long-term outcome is unclear. In the present study, we evaluated the status of 14 males and 19 females aged 8-17 years (mean 11.9 years, median 11.2 years) 4-11 years (mean 6.9 years, median 6.5 years) after the initial diagnosis of idiopathic hypercalciuria not associated with urolithiasis. A questionnaire was answered and two random urine samples provided 3-4 weeks apart were analyzed for calcium (Ca), sodium (Na), potassium (K), and creatinine (Cr). Urine Ca/Cr ratio > or =20.21 (mg/mg) was defined as hypercalciuria. At the time of the study none were under follow-up, although 7 children were still exhibiting voiding symptoms. No child developed clinical urolithiasis. Based on the first urine specimen, 16 of the 33 (48.4%) were hypercalciuric. Their 2nd urinalysis showed persistent hypercalciuria in 8 and normocalciuria in 8. Urine Na/K ratio (mEq/mEq) decreased in the latter 8 from 5.08+/-2.67 to 3.03+/-2.23 (P<0.05). Of the 17 initially normocalciuric children, 5 did not submit a 2nd specimen, 11 remained normocalciuric, and 1 became hypercalciuric with an increase in urine Na/K ratio. Twenty-three children (all 8 persistently and 9 intermittently hypercalciuric plus 6 normocalciuric) were studied by ultrasonography. Only in 1 asymptomatic persistently hypercalciuric child was a single small renal calcification noted. Introduction of a low-Na/high-K diet in 7 persistently hypercalciuric children resulted in a decrease in UNa/K ratio from 7.34+/-2.15 to 4.14+/-3.09 (P<0.01) and UCa/Cr ratio from 0.25+/-0.04 to 0.13+/-0.03 (P<0.01). We conclude that even though over time most hypercalciuric children become asymptomatic, many remain hypercalciuric. Further follow-up is required to ascertain whether these children are at risk of developing kidney stones. If they are at risk then long-term compliance with a low-Na/high-K diet might be beneficial, as it can normalize calciuria in the majority of these children.

Adolescent↗
PubMed2000

Tenckhoff catheters prove superior to cook catheters in pediatric acute peritoneal dialysis.

Peritoneal dialysis (PD) is the most common form of renal replacement therapy in infants and young children with acute renal failure (ARF). The two most commonly used catheters for performing acute PD are the Cook catheter (CC), placed at the bedside, and the surgically placed Tenckhoff catheter (TC). In the present study, we compared the complications and survival rates of the two catheters. The records of 59 children (age, 1 day to 16.7 years) who underwent PD for ARF from March 1989 through June 1999 in our hospital were reviewed. The initial (primary) catheter was a TC in 22 patients and a CC in 37 patients. The age of the patients who received a primary TC (2.8 +/- 4.5 years) was no different than the age of those with a primary CC (1.4 +/- 2.0 years; P = not significant). The duration of use (mean +/- SD) of TCs (16.5 +/- 14.2 days) was significantly greater than the duration of CC use (4.9 +/- 4.2 days; P < 0.001). Only two patients with a TC (9%) developed complications, whereas 18 patients with a CC (49%) developed complications, 13 of whom required catheter replacement (P < 0.01). Thirty-five patients (59%) recovered renal function after undergoing dialysis for 11.5 +/- 8.0 days. Twenty-three of those patients (66%) required dialysis for more than 5 days. Only 4 patients with a primary CC had successful completion of dialysis without catheter-associated complications compared with 15 patients with a primary TC. Kaplan-Meier survival analysis showed that by day 6 of dialysis, only 46% of primary CCs were functioning without complications compared with 90% of TCs that were free of complications. We conclude that the use of a CC is associated with significantly more complications than a TC, and nearly one half of the CCs are likely to be nonfunctional beyond 5 days of dialysis, at a time when two thirds of the patients are still expected to be undergoing dialysis. Therefore, when possible, a TC should be the catheter of choice when initiating acute PD in children. In those patients for whom a CC is chosen as the initial catheter, an elective change to a TC should be considered once dialysis is expected to extend beyond 5 days.

Acute Kidney Injury↗
PubMed1999

High incidence of focal segmental glomerulosclerosis in nephrotic syndrome of childhood.

In recent adult literature, there have been reports of an increasing incidence of focal segmental glomerulosclerosis (FSGS) among patients with nephrotic syndrome. To examine whether this observation is also relevant to the pediatric population we utilized our hospital computerized database to analyze the data on children with primary nephrotic syndrome seen first between the years 1984 and 1995. A questionnaire was also sent to all metropolitan Kansas City pediatricians to identify possible patients outside the database. The inclusion criteria were clinical nephrotic syndrome or proteinuria with a kidney biopsy. A total of 148 patients (group A) were identified; 86 of them from metropolitan Kansas City (group B). In group A the incidence of minimal change disease (MCD) and FSGS was 52.7% [95% confidence interval (CI) 44%-60%] and 23.0% (95% CI 16-29%), respectively and in group B 54.7% (95% CI 44%-65%) and 24.5% (95% CI 15%-33%), respectively. Those numbers were significantly different from the International Study of Kidney Disease in Children (IS-KDC) reported incidence of 76.4% for MCD and 6.9% for FSGS. Similar to the ISKDC, in our population children over 6 years had a higher incidence of FSGS than younger children (32.8% vs. 16.7%, P = 0.028). The annual incidence rate for nephrotic syndrome in group B was 2.2 cases/10(5) children per year, of which MCD comprised 1.22 cases/10(5) children per year and FSGS 0.5 cases/10(5) children per year. The annual incidence rates of both primary nephrotic syndrome (3.6) and FSGS (1.6) were significantly higher in African-Americans, than Caucasians (1.8 and 0.3 cases/10(5) children per year, respectively). Our study indicates nearly no change in the annual incidence of pediatric primary nephrotic syndrome, but a higher incidence of FSGS with reciprocal decline in the incidence of MCD. The possibility of primary nephrotic syndrome being caused by a non-MCD entity is further raised among African-American and in children over 6 years. We conclude that our perception of primary nephrotic syndrome of childhood as a benign condition has to be carefully reexamined and a more-guarded prognostic approach adopted in our geographic area.

Adolescent↗
PubMed1999

Bilateral nephrectomy reverses hypothyroidism in congenital nephrotic syndrome.

A state of biochemical hypothyroidism is commonly seen in infants with congenital nephrotic syndrome (NS) and therefore the current recommendation is to place all patients with congenital NS on supplemental thyroid preparations. We report our experience in five children with congenital NS in whom thyroid supplementation was discontinued following bilateral nephrectomy and initiation of renal replacement therapy. Immediately after nephrectomy, thyroid function tests normalized, except serum thyroid-stimulating hormone (TSH) concentration, which initially rose, but normalized later. This observation supports the hypothesis that hypothyroidism in these patients is secondary to the chronic massive proteinuria and is not the result of a defect intrinsic to the thyroid gland itself. Abatement of massive proteinuria enables discontinuation of thyroid supplementation, and a transient rise in TSH in the early post-nephrectomy stage should be potentially expected.

Child↗
PubMed1999

Should renal ultrasonography be done routinely in children with first urinary tract infection?

To reassess the impact of renal ultrasonography on the care of children with first febrile urinary tract infection (UTI) we conducted a computer search and review of medical records of (1) all children who were admitted to our hospital with first febrile urinary tract infection and underwent renal ultrasonography during a 25-month period beginning February 1, 1995, (2) all children diagnosed by ultrasound to have hydronephrosis during the same time period. Of a total of 124 patients with UTI, renal ultrasound appeared normal or showed evidence of acute pyelonephritis in 105 (84.7%), and in another nine (7.2%) it showed only minor findings. In 10 children (8.1%) ultrasound showed hydronephrosis and/or hydroureter. In eight of the latter 10, voiding cystourethrography showed vesicoureteral reflux; in one, posterior urethral valves; and in one, who had a unilateral nonobstructed dilatated system, cystography appeared normal. Except for the last patient, who was given prophylactic antibiotics and continued to have urinary tract infections, in no other case did ultrasound alone have any impact on the patient's management. Four children with both abnormal-appearing renal ultrasound and voiding cystourethrography required surgical intervention. One hundred of the 124 children had a voiding cystourethrogram. In 38 children it detected vesicoureteral reflux and, in another two, bladder abnormalities. Thirty-five of those with abnormal-appearing cystogram but without an indication for surgery were given prophylactic antibiotics. During the same 25-month period, 63 children without urinary tract infection were diagnosed by ultrasound with hydronephrosis. In 45 of them (71.4%) the urologic abnormality had already been detected by prenatal ultrasound. Fourteen of these 45 children (31.1%) required surgery, all for congenital anomalies related to obstructive uropathy. We conclude that routine renal ultrasonography in children with first urinary tract infection has negligible influence on their clinical management. This seems to be due to the recent widespread use, in industrialized countries, of maternal-fetal ultrasonography, which already detects a significant number of children with congenital obstructive uropathy prenatally. On the other hand imaging of the lower urinary tract is of high yield and contributes significantly to patient care. Therefore, whereas imaging of the lower urinary tract should continue to be done routinely in children with first urinary tract infection, renal ultrasound may be reserved for more select cases.

Female↗
PubMed1999

Bisphosphonates: from grandparents to grandchildren.

Bisphosphonates are synthetic analogues of pyrophosphate that inhibit bone resorption by their action on osteoclasts. Bisphosphonates have been extensively used in the elderly with primary and secondary osteoporosis, Paget's disease, and hypercalcemia of malignancy. In recent years, bisphosphonates have been used to treat children acutely for resistant hypercalcemia and chronically for various metabolic bone diseases. The theoretical concerns of possible adverse effects of these drugs on the growing skeleton have not been proven to be true. In the present review, we have critically analyzed the available literature on bisphosphonate therapy in both adult and pediatric clinical trials. Although not yet approved by the FDA for use in children, bisphosphonates, from published experience, demonstrate benefit to the child with no serious adverse effects. Based on the literature analysis the review furnishes detailed recommendations and practical guidelines regarding the use of oral and intravenous bisphosphonates in children. Bisphosphonates might be the first agents to provide the pediatrician with an opportunity to treat mineral and bone disorders of childhood, which until recently did not have satisfactory therapy.

Administration, Oral↗
PubMed1998

Creatinine clearance following cimetidine for estimation of glomerular filtration rate.

Simultaneous inulin (C[in]) and creatinine clearance (C[Cr]) studies were performed on 53 pediatric renal patients using a cimetidine protocol. Since cimetidine blocks the tubular secretion of creatinine, it was hypothesized that C(Cr) measured following cimetidine would closely approximate the C(in). C(in) was compared with C(Cr) with the latter calculated from: (1) a 24-h urine collection, (2) plasma creatinine, height, and a proportionality constant, (3) the same plasma and urine specimens used for calculating C(in), and (4) from the plasma and urine specimens of the four 30-min clearance periods treated as a single 2-h clearance. The C(in) was very closely approximated by the C(Cr) calculated from the same specimens used for the C(in) and by the 2-h clearance. The cimetidine protocol, with C(Cr) derived from a 2-h urine collection obtained under supervision in the office or clinic, provides a convenient and inexpensive procedure for estimation of glomerular filtration rate in a clinical setting.

Adolescent↗
PubMed1998

Effect of age on furosemide-induced nephrocalcinosis in the rat.

Furosemide (F)-induced nephrocalcinosis (NC) has been traditionally described in low birth weight premature infants. To investigate the role of age on F-induced nephrocalcinosis we studied 24 Sprague-Dawley male rats grouped by age and F therapy vs. control as follows: A (4-week-old control), B (4-week-old + F), C (6-week-old control), D (6-week-old + F), E (10-week-old control), F (10-week-old + F). The rats were placed in metabolic cages for measurement of urine output, food and water intake. At day 14 they were anesthetized, exsanguinated and their kidneys harvested. Renal calcium deposition was assessed using NC score (scale 0-4) and quantitative calcium analysis in the contralateral kidney. Treated animals gained less weight and had higher urine output and fluid intake than the age-matched controls demonstrating the diuretic effect of furosemide. Control groups A, C, and E scored 0 histologically compared with B 2.75 +/- 0.50, D 2.00 +/- 0.58, and F 3.00 +/- 0.82 (p < 0.05 in all three paired groups). Kidney calcium content (micrograms/g dry weight) in B was 2,815.68 +/- 1,553.77 vs. A 202.58 +/- 32.02 (p = 0.04); D 1,574.05 +/- 540.21 vs. C 212.22 +/- 30.91 (p = 0.02); F 2,591.40 +/- 1,269.80 vs. E 210.38 +/- 26.79 (p = 0.02). There was no difference in the magnitude of NC among the three treated groups themselves. To determine the possible effect of age on timing of onset of NC additional 30 4-week-old and 30 10-week-old rats were studied. All 60 rats received furosemide. Six rats from each group were sacrificed on days 1, 3, 5, 7 and 11. In both groups, significant calcifications were seen already on day 3 and maximum calcification noted between days 3 and 5. We conclude that in this model the development of NC occurs within a few days of furosemide administration and that this phenomenon is not age dependent but rather reflects a property of the loop diuretic itself.

Aging↗
PubMed1997

Salt supplementation, growth, and nephrocalcinosis in the furosemide-treated weanling rat.

OBJECTIVE: Furosemide treatment in the human neonate is associated with sodium depletion, growth retardation, hypercalciuria and nephrocalcinosis. Dietary sodium intake is known to directly influence urinary calcium excretion. The objectives of this study were to create a rat model of furosemide-induced nephrocalcinosis and to test the effects of dietary sodium supplementation on growth, electrolyte balance, calciuria, and renal calcifications. METHODS: Initially, 18 weanling Sprague-Dawley rats were randomly divided into three groups. Groups A (control) and B were fed a basal diet. Group C was fed a sodium-enriched diet. Groups B and C received furosemide (40 mg/kg) intraperitoneally daily for 28 days. At the end of the study, serum, urine, and kidney samples were obtained for biochemical and histologic analyses. The three groups were then compared for differences in growth, electrolyte homeostasis, calcium excretion and nephrocalcinosis. Subsequently an additional 15 rats were studied to confirm our findings regarding urinary calcium excretion and kidney calcifications. RESULTS: Treatment with furosemide without sodium supplementation (group B) resulted in decreased weight gain compared with group A (137.5 +/- 12.9 vs 154.0 +/- 10.6 g; p < 0.05), hypokalemia (3.7 +/- 0.1 vs. 4.4 +/- 0.4 mEq/l; p < 0.05), and nephrocalcinosis (187.1 +/- 155 vs. 18.8 +/- 6.9 micrograms Ca/g dry kidney; p < 0.05). Sodium supplementation (group C) normalized weight gain and corrected electrolyte abnormalities without increasing calciuria or nephrocalcinosis. CONCLUSIONS: We conclude that in this animal model, chronic furosemide treatment results in growth failure and development of nephrocalcinosis. Sodium supplementation protects against the deleterious effects of furosemide on weight gain and electrolyte homeostasis with no adverse effect on nephrocalcinosis.

Animals↗
PubMed1997

The relationship between urinary calcium, sodium, and potassium excretion and the role of potassium in treating idiopathic hypercalciuria.

OBJECTIVES: 1) To evaluate the relationships between urinary sodium (UNa), potassium (UK), and calcium (UCa) excretion in the pediatric population; and 2) to determine the effect of increasing potassium intake in patients with idiopathic hypercalciuria and investigate whether this intervention can be offered as another mode of therapy in this patient population. DESIGN: Prospectively, we determined UNa, UK, UCa, and creatinine (Cr) concentrations in randomly collected urine samples from children on initial evaluation for urinary frequency, dysuria, hematuria, enuresis, or kidney stones to identify children with hypercalciuria. SETTING: The outpatient renal clinic of an academic hospital. PARTICIPANTS: Twenty-three black children (13 girls and 10 boys) and 77 white children (44 girls and 33 boys) 3.92 to 16.67 years of age. INTERVENTIONS: Eleven children with hypercalciuria were given potassium supplementation or placed on a high-potassium diet for at least 2 weeks. OUTCOME MEASURES: UNa to UK, UNa to Cr, UK to Cr, and UCa to Cr ratios were calculated from measured levels of urinary minerals. These were repeated in 11 hypercalciuric patients after 2 weeks of increased potassium intake. RESULTS: A total of 100 urine samples were analyzed. The UCa/Cr ratio in blacks 0.04 +/- 0.06 (mean +/- standard deviation) was significantly lower than in whites 0.16 +/- 0.12. There were 21 hypercalciuric white children versus only 1 black child. Linear regression analysis revealed a positive direct correlation between UNa/Cr and UCa/Cr in all 100 subjects and in whites alone but not in blacks. An inverse relationship existed between UK/Cr and UCa/Cr in all subjects and in whites and showed a strong trend in blacks. A marked direct relationship was found between UNa/K and UCa/Cr in all subjects (r = .43) as well as in whites (r = .59) and blacks (r = .49). One black child and 10 white hypercalciuric children were treated with "extra" K for at least 2 weeks. The UNa/K decreased from 4.73 +/- 2.28 to 1.98 +/- 1.09, and the UCa/Cr decreased from 0. 31 +/- 0.10 to 0.14 +/- 0.07, with resolution or improvement of the patients' symptoms. CONCLUSIONS: In our patient population with urinary symptoms, the UCa/Cr ratio in black children is lower and hypercalciuria less common than in white children. In both white and black populations, the UNa/K ratio had the strongest association with the UCa/Cr ratio, indicating an opposing role of UNa and UK on the UCa/Cr ratio. Increased potassium intake was found to be beneficial for hypercalciuric children by decreasing the UNa/K ratio and, consequently, the UCa/Cr ratio.

Adolescent↗