Comparison of serum iohexol clearance and plasma creatinine clearance in clinically normal horses

Abstract

Objective-To determine whether a limited sampling time method based on serum iohexol clearance (Cl(iohexol)) would yield estimates of glomerular filtration rate (GFR) in clinically normal horses similar to those for plasma creatinine clearance (Cl(creatinine)). Animals-10 clinically normal adult horses. Procedures-A bolus of iohexol (150 mg/kg) was administered IV, and serum samples were obtained 5, 20, 40, 60, 120, 240, and 360 minutes after injection. Urinary clearance of exogenous creatinine was measured during three 20-minute periods. The GFR determined by use of serum Cl(iohexol) and plasma Cl(creatinine) was compared with limits of agreement plots. Results-Values obtained for plasma Cl(creatinine) ranged from 1.68 to 2.69 mL/min/kg (mean, 2.11 mL/min/kg). Mean serum Cl(iohexol) was 2.38 mL/min/kg (range, 1.95 to 3.33 mL/min/kg). Limits of agreement plots indicated good agreement between the methods. Conclusions and Clinical Relevance-Use of serum Cl(iohexol) yielded estimates of GFR in clinically normal adult horses similar to those for plasma Cl(creatinine). This study was the first step in the evaluation of the use of serum Cl(iohexol) for estimating GFR in adult horses.

Determination of Glomerular Filtration Rate in Adult Horses and Donkeys by Single IV Administration of Iohexol

“…Plasma clearance of IOX was recently used to evaluate GFR both in adult horses and foals. Wilson et al [29] reported a GFR of 2.38 mL/kg/min in adult horses, whereas Gonda et al [28] obtained a GFR of 2.15 mL/kg/min in foals. Our results obtained in horses with the nine-point method are in line with literature.…”

“…To the authors' knowledge, literature regarding the use of IOX to evaluate GFR in the horse is scarce [28,29], and no data are reported in donkeys. The aims of this study were (1) to estimate GFR using IOX clearance in horses and donkeys and (2) to evaluate the use of limited sampling models to establish an accurate and clinically suitable GFR test.…”

“…Iohexol (IOX) is a nonionic low-osmolarity contrast medium widely used in many species because of its low toxicity. The renal clearance of IOX is close to the renal clearance of inulin in man, thus IOX has been used to estimate GFR both in humans [18][19][20] and in animals [21][22][23][24][25][26][27][28][29].…”

Optimum conditions for serum clearance of iodixanol, applicable to the estimation of glomerular filtration rate in horses

“…The dose of 20 mg I/kg iodixanol corresponded to about one-twenty-sixth the human clinical dose as the contrast medium for angiography, and about one-seventh the iohexol dose (150 mg I/kg) described in the previous report (Wilson et al 2009). The three-blood-sample method is considered to have many practical advantages such as repeated application to the same animals, usage of non-radiolabeled agent and a small amount of serum specimen (80 μL), compared to the previously reported methods in horses (Brewer et al 1988;Gleadhill et al 1999;Matthews et al 1992;Walsh and Royal 1992;Wilson et al 2009;Zatzman et al 1982). However, since species differences in the formula of Bröchner-Mortensen (1972) have not been systematically evaluated, further studies are required to collect cumulative background data including increased number of horses together with clinical cases showing reduced renal function.…”

“…Renal dysfunction in horses may develop secondary to changes in hemodynamics (Gleadhill et al 2000), intrinsic renal diseases, or postrenal diseases (Wilson et al 2009). However, there is no information dealing with a simple prediction of equine GFR.…”