scholarly journals A more accurate replacement for the revised Schwartz equation: quadratic or Flanders metadata? Flaws in the authors reply

2014 ◽  
Vol 85 (1) ◽  
pp. 215-216
Author(s):  
Hans Pottel
Keyword(s):  
Schwartz Equation

Novel estimating equation of GFR in children without height information performs as well as the Schwartz equation

2013 ◽  
Vol 81 (S1) ◽  
pp. 8-8
Author(s):  
Hester N. Blufpand ◽  
Rik Westland ◽  
Gertjan J.L. Kaspers ◽  
Joanna A.E. van Wijk ◽  
Arend Bökenkamp
Keyword(s):  
Estimating Equation ◽  
Schwartz Equation

Elevated Glomerular Filtration Rate (GFR) in Young Patients with Sickle Cell Anemia.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3745-3745
Author(s):  
Sherri A. Zimmerman ◽  
Jacqueline S. Davis ◽  
Nicole A. Mortier ◽  
Russell E. Ware
Keyword(s):  
Renal Function ◽  
Glomerular Filtration Rate ◽  
Young Children ◽  
Glomerular Filtration ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Filtration Rate ◽  
Plasma Clearance ◽  
Glomerular Hyperfiltration ◽  
Schwartz Equation

Abstract Nephropathy is a well-recognized complication of sickle cell anemia (SCA) that is associated with considerable morbidity and mortality. Sickle nephropathy begins early in life, with glomerular damage characterized by hyperfiltration and glomerulomegaly, as well as tubular damage characterized by hyposthenuria. School-aged children can develop proteinuria and one-third of patients will eventually develop chronic renal failure as adults. Among the earliest markers of sickle nephropathy is glomerular hyperfiltration, typically measured as an elevated glomerular filtration rate (GFR). To date, however, no formal measurements of GFR have been published in young children with SCA, and its feasibility and interpretation in this age group have not been demonstrated. As part of a prospective, single-institution, IRB-approved open-label protocol using hydroxyurea in toddlers with SCA, the pre-treatment GFR was measured using plasma clearance of 99-Tc DTPA. The goal of this procedure was to determine the onset of hyperfiltration among young children with SCA, to identify risk factors associated with its onset, and to investigate the potential benefit of hydroxyurea in improving or preserving renal function. After intravenous injection of the DTPA radiotracer, 3–5 mL aliquots of venous blood were removed at 1 and 3 hours post-injection and analyzed for plasma radioactivity. Because DTPA is filtered at the glomerulus without substantial metabolism, secretion, or reabsorption, the plasma clearance allows an accurate and precise GFR measurement. The GFR was also estimated using the Schwartz equation, where GFR = height (cm) x k/serum creatinine, with k=0.55 for children between ages 1 and 12 years. A total of 13 children with HbSS (3 females, 10 males) were enrolled in this study, none of whom had laboratory evidence of renal disease at the time of evaluation. One child could not complete the DTPA study due to inadequate venous access. For the remaining 12 children, baseline GFR measurements were performed at age 3.0 ± 0.8 years (range 1.7 to 4.4 years) without complications. The average GFR measurement (mean ± SD) by DTPA clearance was 140.3 ± 20 mL/min/1.73m2, median 133 mL/min/1.73m2, range 117.9 to 172.7 mL/min/1.73m2 (normal 100 ± 20 mL/min/1.73m2). The baseline DTPA GFR measurement was elevated above 150 mL/min/1.73m2 in 5 of the 12 children, including 4 of 7 over age 3 years, although there was no signfiicant correlation between GFR and age or fetal hemoglobin. GFR estimates by the Schwartz equation were modestly correlated with the DTPA GFR measurements (R2 = 0.32, p = 0.055) but were typically slightly higher than the corresponding DTPA measurements. Three children who completed 24 months of hydroxyurea therapy had post-treatment DTPA clearance studies that revealed stable GFR measurements (average increase = 5.6 mL/min/1.73m2). These results illustrate that GFR measurement by DTPA clearance can be performed without difficulty in young children with SCA, requiring only peripheral intravenous access. Glomerular hyperfiltration as a manifestation of renal damage begins early in life for children with SCA, with elevated GFR values observed in the toddler age range. The Schwartz equation provides an estimate of GFR but probably cannot be used in lieu of the DTPA clearance study. Treatment with hydroxyurea may preserve renal function by abrogating further GFR hyperfiltration.

scholarly journals Height-Independent Estimation of Glomerular Filtration Rate in Children: An Alternative to the Schwartz Equation

2013 ◽  
Vol 163 (6) ◽  
pp. 1722-1727 ◽  
Author(s):  
Hester N. Blufpand ◽  
Rik Westland ◽  
Joanna A.E. van Wijk ◽  
Elianne A. Roelandse-Koop ◽  
Gertjan J.L. Kaspers ◽  
...  
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Schwartz Equation

Is the new Schwartz equation derived from serum creatinine and body length suitable for evaluation of renal function in Japanese children?

2012 ◽  
Vol 171 (9) ◽  
pp. 1401-1404 ◽  
Author(s):  
Osamu Uemura ◽  
◽  
Masataka Honda ◽  
Takeshi Matsuyama ◽  
Kenji Ishikura ◽  
...  
Keyword(s):  
Renal Function ◽  
Serum Creatinine ◽  
Body Length ◽  
Japanese Children ◽  
Schwartz Equation

THE MAIN HASEMAN TYPE BOUNDARY VALUE PROBLEM FOR METAANALYTIC FUNCTION IN THE CASE OF CIRCULAR DOMAINS

2001 ◽  
Vol 6 (1) ◽  
pp. 68-76 ◽  
Author(s):  
B. F. Fatulaev
Keyword(s):  
Boundary Value Problem ◽  
Analytic Functions ◽  
Boundary Value ◽  
Initial Problem ◽  
Circular Domains ◽  
Type Boundary ◽  
Schwartz Equation

In the presented work a main Haseman type boundary value problem is investigated in the class of metaanalytic functions in the case of circular domains. With the help of Schwartz equation for circumference the initial problem can be reduced to the totality of two ordinary Haseman problems for analytic functions. Besides, the picture of solvability of the problem depending on values of indexes of coefficients of boundary value conditions is is investigated in this work.

Evaluation of Renal Function by Glomerular Filtration Rate (GFR) in Infants with Sickle Cell Anemia.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1672-1672
Author(s):  
Winfred C. Wang ◽  
Renee R. Rees ◽  
Daner Li ◽  
Zora Rogers ◽  
Rathi Iyer ◽  
...  
Keyword(s):  
Renal Function ◽  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Filtration Rate ◽  
Plasma Clearance ◽  
Renal Damage ◽  
Phase Iii ◽  
Schwartz Equation

Abstract Chronic anemia and intraparenchymal sickling within the kidney lead to intravascular volume expansion and an increased glomerular filtration rate (GFR) in sickle cell anemia (SCA). An elevated GFR is considered to be an early indicator of renal damage in SCA, and the pathophysiologic changes leading to sickle nephropathy and elevated GFR likely begin at a young age. The Pediatric Hydroxyurea Phase III Clinical Trial (BABY HUG), an NHLBI-sponsored multi-center double-blinded placebo-controlled study, compares hydroxyurea versus placebo in infants with SCA, with the primary goal of determining the efficacy of hydroxyurea for the prevention of organ dysfunction in the spleen and kidney. In the Feasibility and Safety Pilot, a primary objective is to assess GFR in infants with SCA between the age of 12 and 18 months by measuring plasma clearance of 99m Tc-DTPA (diethylenetriaminepentaacetic acid) and by estimating GFR using the Schwartz equation. The DTPA GFR was determined following administration of an IV bolus of 25–50 μCi/kg of the radiotracer, with venous blood samples obtained at 1, 2, and 4 hours. GFR was also calculated using the Schwartz equation: 0.55 x body length (cm) ÷ plasma creatinine (mg/dL). For both measurements, a logarithmic transformation was applied to improve linearity between the variables, and to stabilize the variance of the transformed data. To date, 17 infants with SCA (median age 13.2 months) have had GFR measurements, with no complications occurring. The geometric mean of the GFR (± SD) as measured by DTPA plasma clearance was 112 ± 14.6 mL/min/1.73m2 (range 53–178 mL/min/1.73m2). By regression analysis, the GFR was correlated with age, with an increase of approximately 10% per month (univariate p = 0.006, multivariate p = 0.02), and this correlation could not be ascribed to other age-adjusted changes in hemoglobin concentration (p = 0.35), % fetal hemoglobin (HbF, p = 0.67), white blood cell (WBC) count (p = 0.64), or platelet count (p = 0.76). The estimated GFR calculated by the Schwartz equation was not significantly correlated with age (univariate p = 0.12), and adjustments using hemoglobin, %HbF, platelet or WBC counts did not improve the correlation. There was a modest correlation between GFR determined by DTPA and the Schwartz equation (r = 0.44; p = 0.08). These data indicate that (1) GFR measurement using DTPA plasma clearance is feasible in one year-old infants with SCA; (2) renal damage as measured by an elevated DTPA GFR appears to be present early in life and to be increasing with age; (3) preliminary evaluation of the use of the Schwartz formula indicates only a modest level of correlation with results obtained using DTPA measurements; and (4) in the BABY HUG trial, further evaluation of the efficacy of hydroxyurea in preservation of renal function will likely require DTPA GFR measurements rather than GFR estimates using the Schwartz equation.

scholarly journals A more accurate replacement for the revised Schwartz equation: quadratic or Flanders metadata?

2013 ◽  
Vol 84 (2) ◽  
pp. 416-417 ◽  
Author(s):  
Alaleh Gheissari ◽  
Peyman Roomizadeh ◽  
Amin Abedini
Keyword(s):  
Schwartz Equation

Modifying the “Modified Schwartz Equation” for Lung Cancer Volume Estimates

2015 ◽  
Vol 22 (11) ◽  
pp. 1466 ◽  
Author(s):  
David F. Yankelevitz ◽  
Mingzhu Liang ◽  
Xueguo Liu ◽  
Claudia I. Henschke
Keyword(s):  
Lung Cancer ◽  
Volume Estimates ◽  
Schwartz Equation

scholarly journals The role of cystatin C and various methods of glomerular filtration rate calculation in evaluation of renal dysfunction in children with acute infectious diarrhea

2020 ◽  
Vol 49 ◽  
Author(s):  
O. L. Chugunova ◽  
E. Yu. Grebеnkina ◽  
D. V. Usenko ◽  
I. I. Volodina ◽  
E. V. Galeeva ◽  
...  
Keyword(s):  
Renal Dysfunction ◽  
Cystatin C ◽  
Filtration Rate ◽  
Kidney Injury ◽  
Infectious Diarrhea ◽  
Serum Cystatin C ◽  
Serum Cystatin ◽  
Acute Period ◽  
Acute Kidney Injury Development ◽  
Schwartz Equation

Rationale: Acute infectious diarrhea (AID) is the fourth leading cause of death among children <5 years worldwide. Kidney damage is one of the poorly studied aspects of pediatric AID. The level of serum cystatin C is independent on gender and age, and it is highly informative even in the early stages of renal dysfunction.Aim: To optimize diagnosis of renal dysfunction in children with moderate AID through comparison of different methods of glomerular filtration rate (GFR) calculation and determination of serum cystatin C level.Materials and methods: Observational cross-sectional study enrolled 80  children in pediatric hospital with moderate AID not followed by hemolytic uremic syndrome. Serum creatinine and serum cystatin C levels were determined in all the patients in acute period with GFR calculating according to Schwartz equation in unmodified (1976) and modified (2009) versions. GFR was also calculated using a  single-factor equation based on serum cystatin C level.Results: GFR in acute period, calculated according to unmodified and to modified Schwartz equation was in patients <3  years (n=40) 115.47±3.33  ml/min/1.73  m2  and 98.56±2.84  ml/min/1.73  m2  (p<0.001), in patients 3–7  years 132.13±4.2  ml/min/1.73  m2 and 108.85±3.84  ml/min/1.73  m2  (p<0.001), respectively. Increased serum cystatin  C level (>950  ng/ml) occurred in 18  patients (22%). In other patients level of serum cystatin  C remained within the reference range or lower. The risk of acute kidney injury development based on two indicators  – GFR according to the modified Schwartz equation and GFR according to the equation used cystatin C level  – occurred in 4  (10%) patients aged 1–3  years and in 1  (2.5%) child in the age group 3–7  years; risk, based on one indicator  – the calculation of GFR according to the formula using cystatin C  – in 8  (20%) and 9 (22.5%) children, respectively, and based on the assessment of only GFR according to the modified Schwartz equation  – in 3  (7.5%) children of both age groups.Conclusion: We have confirmed that the GFR values calculated with usage of unmodified Schwartz equation (1976) are higher than those calculated with usage of modified Schwartz equation (2009) and taking into account the level of cystatin  C. Thus, usage of unmodified Schwartz equation for GFR calculation in infants and preschool children seems incorrect. Level of serum cystatin C is promising marker permitted to select patients with risk of acute kidney injury development among children in acute period of moderate AID.

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