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Ng DK, Furth SL, Warady BA, Crews DC, Seegmiller JC, Schwartz GJ. Self-reported Race, Serum Creatinine, Cystatin C, and GFR in Children and Young Adults With Pediatric Kidney Diseases: A Report From the Chronic Kidney Disease in Children (CKiD) Study. Am J Kidney Dis 2022; 80:174-185.e1. [PMID: 34974031 PMCID: PMC9243196 DOI: 10.1053/j.ajkd.2021.10.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 10/24/2021] [Indexed: 01/27/2023]
Abstract
RATIONALE & OBJECTIVE Recent reassessment of the use of race in estimated glomerular filtration rate (eGFR) in adults has instigated questions about the role of race in eGFR expressions for children. Little research has examined the associations of self-reported race with measured GFR (mGFR) adjusting for serum creatinine or cystatin C in children and young adults with chronic kidney disease (CKD). This study examined these associations and evaluated the performance of the previously published "U25" (under the age of 25 years) eGFR equations in a large cohort of children and young adults with CKD. STUDY DESIGN Observational cohort study. SETTING & PARTICIPANTS Participants in the Chronic Kidney Disease in Children (CKiD) study including 190 Black and 675 non-Black participants contributing 473 and 1,897 annual person-visits, respectively. EXPOSURE Self- or parental-reported race (Black, non-Black). Adjustment for serum creatinine or cystatin C, body size, and socioeconomic status. OUTCOME mGFR based on iohexol clearance. ANALYTICAL APPROACH Linear regression with generalized estimating equations, stratified by age (<6, 6-12, 12-18, and ≥18 years) incorporating serum creatinine or serum cystatin C. Contrasting performance in different self-reported racial groups of the U25 eGFR equations. RESULTS Self-reported Black race was significantly associated with 12.8% higher mGFR among children in regression models including serum creatinine. Self-reported Black race was significantly associated with 3.5% lower mGFR after adjustment for cystatin C overall but was not significant for those over 12 years. The results were similar after adjustment for body size and socioeconomic factors. The average of creatinine- and cystatin C-based U25 equations was unbiased by self-reported race groups. LIMITATIONS Small number of children < 6 years; lean body mass was estimated. CONCLUSIONS Differences in the creatinine-mGFR relationship by self-reported race were observed in children and young adults with CKD and were consistent with findings in adults. Smaller and opposite differences were observed for the cystatin C-mGFR relationship, especially in the younger age group. We recommend inclusion of children for future investigations of biomarkers to estimate GFR. Importantly, for GFR estimation among those under 25 years of age, the average of the new U25 creatinine and cystatin C equations without race coefficients yields unbiased estimates of mGFR.
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Affiliation(s)
- Derek K. Ng
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Susan L. Furth
- Children’s Hospital of Philadelphia, Philadelphia, PA, USA,Department of Pediatrics, Division of Nephrology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Bradley A. Warady
- Division of Pediatric Nephrology, Children’s Mercy Kansas City, Kansas City, MO, USA
| | - Deidra C. Crews
- Division of Nephrology, Department of Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Jesse C. Seegmiller
- Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota, Minneapolis, MN
| | - George J. Schwartz
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
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Abstract
Renal functional reserve (RFR) is described as the difference between a glomerular filtration rate (GFR) measured at baseline and after protein stimulation. The percent change in GFR after a protein load varies based on differences in experimental conditions, with the use of an oral meat protein stimulus and a creatinine clearance method to quantify GFR showing the greatest RFR. A decline in RFR has been found in numerous patient groups. Recent investigations have suggested that a lower RFR may be associated with an increased risk of acute kidney injury and eventual chronic kidney disease.
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Affiliation(s)
- Dana Y Fuhrman
- Pediatrics, Critical Care Medicine, and Nephrology, Department of Critical Care Medicine, The Center for Critical Care Nephrology, University of Pittsburgh School of Medicine, UPMC Children's Hospital of Pittsburgh, 4401 Penn Avenue, Children's Hospital Drive, Faculty Pavilion, Suite 2000, Pittsburgh, PA 15224, USA.
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Schwartz GJ, Cox C, Seegmiller JC, Maier PS, DiManno D, Furth SL, Warady BA, Munoz A. Recalibration of cystatin C using standardized material in Siemens nephelometers. Pediatr Nephrol 2020; 35:279-285. [PMID: 31680199 PMCID: PMC7249730 DOI: 10.1007/s00467-019-04389-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/06/2019] [Accepted: 09/27/2019] [Indexed: 10/25/2022]
Abstract
BACKGROUND Cystatin C is a key GFR biomarker. Recently, Siemens recalibrated the assay based on certified reference material ERM-DA471/IFCC. The NIH-funded longitudinal chronic kidney disease in children (CKiD) study has > 3000 cystatin C measurements based on a pre-IFCC calibrator provided by Siemens. Since cystatin C values for CKiD are now standardized to IFCC certified reference material, it is important to relate the IFCC-calibrated results to the previous values so that there are no discontinuous results. METHODS We diluted cystatin C ERM-DA471/IFCC (5.48 mg/L) into buffer and compared results with predicted ones. We then updated the cystatin C application on our BN II nephelometer to provide results based on pre-IFCC and IFCC calibrations of CKiD specimens simultaneously. We assayed 51 previously analyzed sera and 62 fresh additional specimens. RESULTS The predicted concentrations from the IFCC standard were consistently 17% higher than the measured values using the pre-IFCC calibration (y = 1.1686x). Similarly, the re-run and fresh sample concentrations were 17% higher via the IFCC calibration than by the pre-IFCC calibration (y = 1.168x). There was very high reliability in the measurements using the previous calibration for re-run specimens (0.99) and for 33 pristine specimens using IFCC calibration (0.99). CONCLUSIONS We confirm the recalibration proposed by Siemens. To convert pre-IFCC results to IFCC-calibrated concentrations, the value is multiplied by 1.17. Conversely, one divides IFCC-calibrated results by 1.17 to estimate GFR via previously published pre-IFCC CKiD eGFR equations. For older adolescents, cystatin C has already been standardized and can be directly applied to the CKD-EPI equations.
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Affiliation(s)
| | | | | | | | - Donna DiManno
- University of Rochester Medical Center, Rochester, NY
| | - Sue L Furth
- Children’s Hospital of Philadelphia, Philadelphia, PA
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Lillås BS, Tøndel C, Gjerde A, Vikse BE. Measurement of renal functional response using iohexol clearance-a study of different outpatient procedures. Clin Kidney J 2019; 14:181-188. [PMID: 33564417 PMCID: PMC7857819 DOI: 10.1093/ckj/sfz167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 10/21/2019] [Indexed: 11/14/2022] Open
Abstract
Background Glomerular filtration rate (GFR) increases after a heavy protein load; an increase termed renal functional response (RFR). Decreased RFR could be a marker of early kidney damage, but published methods are cumbersome in the outpatient setting. The present study investigates the use of iohexol clearance to measure RFR in outpatients using both one- and two-sample methods. Methods Fourteen healthy volunteers with a mean ± SD age of 42 ± 12 years were included (six males and eight females). GFR was measured using plasma iohexol clearance with one- and two-sample methodologies. Four measurements in each individual were performed: one baseline test and three protein loading tests containing 80 g protein (commercially available protein supplementations from Myo Nutrition and Proteinfabrikken and 350 g chicken breast). RFR was calculated as percentage increase in GFR from the baseline test. Results Mean RFR was 11.4 ± 5.4% and 12.1 ± 6.4% using one- and two-sample methods, respectively. The three different protein loads resulted in similar mean RFR but there was considerable intra-individual variability. One- and two-sample methods for measurement of RFR showed similar results with near-identical means, but there was some intra-individual variation that was similar for different protein loads. The overall 95% limit of agreement between one- and two-sample methods for calculating RFR was -8.7 to 7.3. Conclusions RFR can be investigated using plasma iohexol clearance in an outpatient setting. Protocols using commercially available protein supplementation showed a mean RFR of about 12%. One- and two-sample methods for measuring RFR yield similar results.
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Affiliation(s)
- Bjørn Steinar Lillås
- Department of Medicine, Haugesund Hospital, Haugesund, Norway.,Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Camilla Tøndel
- Department of Clinical Medicine, University of Bergen, Bergen, Norway.,Department of Pediatrics, Haukeland University Hospital, Bergen, Norway
| | - Anna Gjerde
- Department of Medicine, Haugesund Hospital, Haugesund, Norway.,Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Bjørn Egil Vikse
- Department of Medicine, Haugesund Hospital, Haugesund, Norway.,Department of Clinical Medicine, University of Bergen, Bergen, Norway
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Cochat P, Febvey O, Bacchetta J, Bérard E, Cabrera N, Dubourg L. Towards adulthood with a solitary kidney. Pediatr Nephrol 2019; 34:2311-2323. [PMID: 30276534 DOI: 10.1007/s00467-018-4085-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 08/03/2018] [Accepted: 09/10/2018] [Indexed: 02/07/2023]
Abstract
Around 1/1000 people have a solitary kidney. Congenital conditions mainly include multicystic dysplastic kidney and unilateral renal aplasia/agenesis; acquired conditions are secondary to nephrectomy performed because of urologic structural abnormalities, severe parenchymal infection, renal trauma, and renal or pararenal tumors. Children born with congenital solitary kidney have a better long-term glomerular filtration rate than those with solitary kidney secondary to nephrectomy later in life. Acute and chronic adaptation processes lead to hyperfiltration followed by fibrosis in the remnant kidney, with further risk of albuminuria, arterial hypertension, and impaired renal function. Protective measures rely on non-pharmacological renoprotection (controlled protein and sodium intake, avoidance/limitation of nephrotoxic agents, keeping normal body mass index, and limitation of tobacco exposure). Lifelong monitoring should include blood pressure and albuminuria assessment, completed by glomerular filtration rate (GFR) estimation in case of abnormal values. In the absence of additional risk factors to solitary kidney, such assessment can be proposed every 5 years. There is no current consensus for indication and timing of pharmacological intervention.
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Affiliation(s)
- Pierre Cochat
- Centre de référence des maladies rénales rares Néphrogones, Hospices Civils de Lyon, Lyon, France.
- EPICIME Epidémiologie Pharmacologie Investigation Clinique Information Médicale de l'Enfant, Hospices Civils de Lyon, Lyon, France.
- Université Claude-Bernard Lyon 1, Lyon, France.
- Service de Néphrologie Rhumatologie Dermatologie Pédiatriques, Hôpital Femme Mère Enfant, 59 Boulevard Pinel, 69677, Bron Cedex, France.
| | - Olivia Febvey
- EPICIME Epidémiologie Pharmacologie Investigation Clinique Information Médicale de l'Enfant, Hospices Civils de Lyon, Lyon, France
| | - Justine Bacchetta
- Centre de référence des maladies rénales rares Néphrogones, Hospices Civils de Lyon, Lyon, France
- EPICIME Epidémiologie Pharmacologie Investigation Clinique Information Médicale de l'Enfant, Hospices Civils de Lyon, Lyon, France
- Université Claude-Bernard Lyon 1, Lyon, France
| | | | - Natalia Cabrera
- Centre de référence des maladies rénales rares Néphrogones, Hospices Civils de Lyon, Lyon, France
| | - Laurence Dubourg
- Centre de référence des maladies rénales rares Néphrogones, Hospices Civils de Lyon, Lyon, France
- Université Claude-Bernard Lyon 1, Lyon, France
- Exploration fonctionnelle rénale, Hospices Civils de Lyon, Lyon, France
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De Moor B, Vanwalleghem JF, Swennen Q, Stas KJ, Meijers BKI. Haemodynamic or metabolic stimulation tests to reveal the renal functional response: requiem or revival? Clin Kidney J 2018; 11:623-654. [PMID: 30288259 PMCID: PMC6165749 DOI: 10.1093/ckj/sfy022] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 02/26/2018] [Indexed: 12/24/2022] Open
Abstract
Renal stimulation tests document the dynamic response of the glomerular filtration rate (GFR) after a single or a combination of stimuli, such as an intravenous infusion of dopamine or amino acids or an oral protein meal. The increment of the GFR above the unstimulated state has formerly been called the renal functional reserve (RFR). Although the concept of a renal reserve capacity has not withstood scientific scrutiny, the literature documenting renal stimulation merits renewed interest. An absent or a blunted response of the GFR after a stimulus indicates lost or diseased nephrons. This information is valuable in preventing, diagnosing and prognosticating acute kidney injury and pregnancy-related renal events as well as chronic kidney disease. However, before renal function testing is universally practiced, some shortcomings must be addressed. First, a common nomenclature should be decided upon. The expression of RFR should be replaced by renal functional response. Second, a simple protocol must be developed and propagated. Third, we suggest designing prospective studies linking a defective stimulatory response to emergence of renal injury biomarkers, to histological or morphological renal abnormalities and to adverse renal outcomes in different renal syndromes.
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Affiliation(s)
- Bart De Moor
- Faculty of Medicine and Life Sciences, University of Hasselt, Diepenbeek, Belgium
- Department of Nephrology, Jessa Hospital of Hasselt, Hasselt, Belgium
| | | | - Quirine Swennen
- Faculty of Medicine and Life Sciences, University of Hasselt, Diepenbeek, Belgium
| | - Koen J Stas
- Department of Nephrology, Jessa Hospital of Hasselt, Hasselt, Belgium
| | - Björn K I Meijers
- Department of Nephrology, Universitair Ziekenhuis Leuven, Leuven, Belgium
- Department of Immunology and Microbiology, Faculty of Medicine, Katholieke Universiteit Leuven, Leuven, Belgium
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Mian AN, Schwartz GJ. Measurement and Estimation of Glomerular Filtration Rate in Children. Adv Chronic Kidney Dis 2017; 24:348-356. [PMID: 29229165 DOI: 10.1053/j.ackd.2017.09.011] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Rapid, accurate, and precise measures of kidney function are essential for daily management of patients. While plasma and urinary clearances provide the greatest accuracy for assessing glomerular filtration rate (GFR), these are often impractical particularly for the care of children. Serum creatinine, the most commonly used endogenous marker, is simple, convenient, and practical but less accurate because of the influence of non-GFR determinants such as muscle mass, which increases with age in children. GFR estimating equations have been developed for adults and children to improve the accuracy of endogenous biomarkers, such as creatinine and cystatin C, by accounting for some of the non-GFR determinants, thus enhancing the practitioner's ability to assess GFR. In the steady state, when height is used as a surrogate for growth, there is a strong correlation between height/SCr and GFR. Current national guidelines recommend routine reporting of the estimated GFR alongside the serum creatinine value for adults using the Chronic Kidney Disease Epidemiology Collaboration creatinine-based formula and the updated Schwartz "bedside" formula (CKiD 2009) for children.
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