The clearance of iohexol as a measure of the glomerular filtration rate in children with chronic renal failure

Stake, G; Monn, E; Rootwelt, K; Monclair, Tom

doi:10.3109/00365519109104587

Cited by 44 publications

(25 citation statements)

References 21 publications

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“…However, the effect of duration of the study to measure the precision of plasma clearance or compare the GFR estimates resulting from different durations have not been rigorously analyzed although several investigators have pointed to the need for longer sampling intervals when measuring GFR (22)(23)(24) (23). In children, for GFR below 20 ml/ min/1.73m 2 , GFR was overestimated by 50% from plasma iohexol sampled 3.5 h after injection when compared with plasma sampled at 24 h (25).…”

Section: Discussionmentioning

confidence: 99%

Assessment of Iothalamate Plasma Clearance

Agarwal¹,

Bills²,

Yigazu³

et al. 2009

Clinical Journal of the American Society of Nephrology

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Background and objectives: Measurement of GFR is important for the management of chronic kidney disease (CKD).Although bolus administration of radiocontrast agents is commonly used to measure GFR, the optimal duration of sampling to assess their plasma clearance is unknown. The purpose of this study was to evaluate whether the duration of plasma sampling influences precision and estimation of GFR.Design, setting, participants, & measurements: GFR was measured by sampling plasma 12 times over 5 h in 56 patients with CKD (mean age 64 yr, 98% men, 79% Caucasian, 34% diabetics, estimated GFR 31.8 ؎ 14.2 ml/min/1.73 m 2 ). In a subset of 12 patients we measured GFR by sampling plasma 17 times over 10 h.Results: Short sampling intervals considerably overestimated GFR measured using total plasma iothalamate clearance, especially in larger patients. In the higher estimated GFR group (>30 ml/min/1.73m2 ), the 5-h GFR was 17% higher and 2-h GFR 54% higher compared with the 10-h GFR, which averaged 40.3 ml/min/1.73 m 2 . In the lower estimated GFR group (<30 ml/min/1.73m2 ), the 5-h GFR was 36% higher and 2-h GFR 126% higher compared with the 10-h GFR, which averaged 22.2 ml/min/1.73 m 2 . Short sampling duration also reduced the precision of the estimated GFR from 1.67% for 10-h GFR, to 3.48% for 5-h GFR, and to 7.07% for 2-h GFR.Conclusions: GFR measured over a longer duration with multiple plasma samples spanning the distribution and elimination phases may improve precision and provide a better measure of renal function.

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Section: Discussionmentioning

confidence: 99%

Assessment of Iothalamate Plasma Clearance

Agarwal¹,

Bills²,

Yigazu³

et al. 2009

Clinical Journal of the American Society of Nephrology

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“…In children, because of the lower absolute GFR compared with adults, an accurate plasma disappearance curve should be based on blood samples taken over at least 5 h (31,36). In the setting of CKD and severely reduced GFR, or in premature infants, late sampling should be performed 8 to 24 h after injection (36,37).…”

Section: Iohexol Clearancementioning

confidence: 99%

Measurement and Estimation of GFR in Children and Adolescents

Schwartz

Work

2009

Clinical Journal of the American Society of Nephrology

826

604

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GFR is the best indicator of renal function in children and adolescents and is critical for diagnosing acute and chronic kidney impairment, intervening early to prevent end-stage renal failure, prescribing nephrotoxic drugs and drugs cleared by a failing kidney, and monitoring for side effects of medications. Renal inulin clearance was the gold standard for GFR but is compromised by lack of availability, difficult assays, and problems of collecting timed urine samples, especially in children with vesicoureteral reflux or bladder dysfunction. Creatinine clearance-based estimates of GFR are often used in pediatrics. The addition of cimetidine to eliminate creatinine secretion permits accurate measurement of GFR in those who can completely empty their bladders to provide timed urine collections. Radioisotopes are used in plasma disappearance GFR determinations; however, these are not ideal for use in children, especially for repeated studies. The plasma disappearance of iohexol serves as a promising alternative GFR marker, because it is safe and not radioactive, easily measured, not metabolized or transported by the kidney, and excreted primarily by glomerular filtration. GFR estimating equations, based on serum concentrations of creatinine or cystatin C, are popular clinically and in research studies. Efforts are ongoing to improve these estimating equations for children and make the results readily available to clinicians obtaining standard chemistry profiles, as is being done for adults. However, at this time, there is no dependable substitute for an accurately determined GFR, and iohexol plasma disappearance offers the best combination of safety, accuracy, and reproducible precision.

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“…1,2,6 GFR as estimated by the Schwartz formula has been used as one of the enrollment criteria for the Chronic Kidney Disease in Children (CKiD) study, an National Institutes of Health-funded North American cohort study whose goal is to recruit children and adolescents with mild to moderate chronic kidney disease (CKD) and characterize progression and the effects of CKD on cardiovascular, growth, and behavioral indices. We used iohexol plasma disappearance as a gold standard in measuring GFR (iGFR) on the basis of its success as such an agent in Scandinavian adults 7,8 and children, 9,10 as well as in our recently published pilot study. 11 Iohexol is used as a safe, nonionic, low-osmolar contrast agent of molecular weight 821 Da (Omnipaque).…”

mentioning

confidence: 99%

New Equations to Estimate GFR in Children with CKD

Schwartz

Muñoz

Schneider

et al. 2009

Journal of the American Society of Nephrology

3,045

2,267

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The Schwartz formula was devised in the mid-1970s to estimate GFR in children. Recent data suggest that this formula currently overestimates GFR as measured by plasma disappearance of iohexol, likely a result of a change in methods used to measure creatinine. Here, we developed equations to estimate GFR using data from the baseline visits of 349 children (aged 1 to 16 yr) in the Chronic Kidney Disease in Children (CKiD) cohort. Median iohexol-GFR (iGFR) was 41.3 ml/min per 1.73 m 2 (interquartile range 32.0 to 51.7), and median serum creatinine was 1.3 mg/dl. We performed linear regression analyses assessing precision, goodness of fit, and accuracy to develop improvements in the GFR estimating formula, which was based on height, serum creatinine, cystatin C, blood urea nitrogen, and gender. This formula yielded 87.7% of estimated GFR within 30% of the iGFR, and 45.6% within 10%. In a test set of 168 CKiD patients at 1 yr of follow-up, this formula compared favorably with previously published estimating equations for children. Furthermore, with height measured in cm, a bedside calculation of 0.413*(height/serum creatinine), provides a good approximation to the estimated GFR formula. Additional studies of children with higher GFR are needed to validate these formulas for use in screening all children for CKD.

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The clearance of iohexol as a measure of the glomerular filtration rate in children with chronic renal failure

Cited by 44 publications

References 21 publications

Assessment of Iothalamate Plasma Clearance

Assessment of Iothalamate Plasma Clearance

Measurement and Estimation of GFR in Children and Adolescents

New Equations to Estimate GFR in Children with CKD

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