ESPN 50th Annual Meeting

ESPN 2017


 
Single-point iohexol plasma clearance in children: validation of multiple formulas and sampling times
CAMILLA TøNDEL 1 CATHRIN LYTOMT SALVADOR 2 KARL OVE HUFTHAMMER 1 BJøRN BOLANN 1 BRACKMAN DAMIEN 1 ANNA BJERRE 2 EINAR SVARSTAD 1 ATLE BRUN 1

1- HAUKELAND UNIVERSITY HOSPITAL, BERGEN, NORWAY
2- OSLO UNIVERSITY HOSPITAL, OSLO, NORWAY
 
Introduction:

The non-ionic agent iohexol is increasingly seen as the marker of choice for glomerular filtration rate (GFR) measurement. Since estimated GFR (eGFR) has low accuracy in children and limitation of number of blood draws to a minimum is especially relevant in children, we performed a study to evaluate different methods and find the optimal sampling point for calculating measured GFR (mGFR) based on iohexol clearance with a blood sample drawn at only one time-point (GFR1p).

Material and methods:

96 children with chronic kidney disease (CKD), median age 9.2 years, range 3 months to 17.5 years, were examined using iohexol plasma clearance and blood sampling at seven time points within five hours (GFR7p) as the reference method. Median GFR7p was 65.9 mL/min/1.73m2, range 6.3 – 153 mL/min/1.73m2. The performances of six different formulas (Fleming-2005, Ham-1991a, Ham-1991b, Stake-1991, Groth-1984, Jacobsson-1983) were validated against the reference.

Results:

GFR1p calculated according to the formula of Fleming with sampling at 3 hours, had the best performance with 80 percent within +/-10 percent of the reference (P10). The Fleming formula gave GFR1p with significantly better P10 (p < 0.05) than all other tested formulas with sampling at 2 hours, 3 hours and 3.5 hours. With sampling at 4 hours both the Fleming formula and the Jacobsen formula performed significantly better than the other formulas with P10 of 73 and 70 percent, respectively. At 5 hours the formula of Jacobsen had the best performance with P10 of 74 percent, significantly better than all other tested formulas.

Conclusions:

The Fleming formula with sampling at 3 hours is recommended when GFR1p is used in children with CKD.