title: Measurement of glomerular filtration rate by rapid intravenous injection of a newly developed inulin fraction.
abstract: OBJECTIVE
  Since the conventional drip-infusion method for measuring inulin clearance (Cin) has problems related to its accuracy and performance, we explored a more accurate and concise method by rapid intravenous injection of a newly developed inulin fraction (Inulead(®)), in which spot urine sampling was omitted and the administration period of inulin was shortened from 120 to 5 minutes.
  
  
  METHODS
  Twenty seven patients (M/F: 15/12, 67.8 ± 12.9 years old) admitted to the Nephrology ward were enrolled in this study. Inulead(®), 1500 mg dissolved in 150 mL of saline, was intravenously administered in 5 minutes. Then, sequential blood samplings and urine collection were performed for 24 hours. Cins were calculated by the following three formulae: (1) a pharmacokinetic analysis using a two compartments model based on the plasma inulin concentration to determine Cin, which was the administered dose divided by the area under the curve (AUC) from 0 to ∞, (2) urinary inulin excretion divided by the AUC for 24 hours and (3) the Bayesian method using a three-point set of plasma inulin concentrations to predict the change of inulin concentration to determine Cin as in 1. These Cins were compared with levels of estimated GFR (eGFR), creatinine clearance (Ccr), serum β2 microglobulin (β2MG) and serum cystatin C (Cys C).
  
  
  RESULTS
  Cins obtained by the above three methods were well correlated with each other (r. = 0.9088 (- )0.9998) and with eGFR (r. = 0.8286 - 0.8650), Ccr (r. = 0.821 - 0.864), 1/β2MG (r. = 0.631 - 0.752) and 1/CysC (r. = 0.830 - 0.857). The averaged differences of each Cin from eGFR were distributed between - 4.4 and - 4.5 mL/min.
  
  
  CONCLUSIONS
  Since the Cins by rapid inulin injection showed satisfactory correlation and differences with other GFR parameters, this method will be a good alternative to the drip infusion method, and may reduce the burden of patients and medical staff.
authors: Nephrology Division, Department of Internal Medicine, Toride Kyodo General Hospital, Japan.
authors: Yoshitaka
authors: Y
authors: Maeda
authors: Nephrology Division, Department of Internal Medicine, Toride Kyodo General Hospital, Japan.
authors: Yuya
authors: Y
authors: Araki
authors: Nephrology Division, Department of Internal Medicine, Toride Kyodo General Hospital, Japan.
authors: Tomomi
authors: T
authors: Uno
authors: Nephrology Division, Department of Internal Medicine, Toride Kyodo General Hospital, Japan.
authors: Akiko
authors: A
authors: Yoshida
authors: Nephrology Division, Department of Internal Medicine, Toride Kyodo General Hospital, Japan.
authors: Keisuke
authors: K
authors: Nishigaki
authors: Nephrology Division, Department of Internal Medicine, Toride Kyodo General Hospital, Japan.
authors: Naoto
authors: N
authors: Inaba
authors: Department of Drug Disposition & Pharmacokinetics, School of Pharmaceutical Sciences, Teikyo University, Japan.
authors: Hiroaki
authors: H
authors: Hayashi
authors: Department of Drug Disposition & Pharmacokinetics, School of Pharmaceutical Sciences, Teikyo University, Japan.
authors: Yoshiharu
authors: Y
authors: Deguchi
keywords: Area Under the Curve (AUC); Bayesian method; Chronic Kidney Disease (CKD); Inulead; inulin clearance
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