¹²⁵I-Sodium Iothalamate in the Determination of the Glomerular Filtration Rate

Summary

One hundred ¹²⁵I-sodium iothalamate and endogenous creatinine clearances in 36 subjects were compared with standard inulin clearance measurements. There was a very close correlation of the urine/plasma ratios between any two of the three clearances studied, hence both labelled iothalamate and creatinine can be relied upon for the estimation of the glomerular filtration rate in clinical practice. The mean ratio of ¹²⁵I-sodium iothalamate to inulin clearance was 1.01 and that of creatinine to inulin 1.03. It is concluded that the clearance of ¹²⁵I-sodium iothalamate can be substituted for the clearance of inulin in clinical determinations of the glomerular filtration rate but that in centres without radioisotope facilities the endogenous creatinine clearance can be used instead.

Chez 36 sujets, 100 déterminations de la clearance du ¹²⁵I-iothalamate de soude et de celle de la créatinine endogène ont été faites simultanément avec des déterminations de la clearance d’inuline en vue de les comparer. Les quotients urine : plasma des concentrations de chacune de ces trois substances avaient une corrélation très étroite, et par conséquent en pratique clinique, la détermination de la filtration glomérulaire peut s’effectuer avec de l’iothalamate de soude ou avec de la créatinine. La valeur moyenne du quotient clearance de l’iothalamate/clearance de l’inuline était de 1.01, celle du quotient clearance de la créatinine/clearance de l’inuline de 1.03. Il est évident que la clearance du ¹²⁵I-iothalamate de soude pourrait remplacer celle de l’inuline pour la détermination de la filtration glomerulaire en clinique. Dans l’absence de laboratoires isotopiques, cependant, la clearance de la créatinine endogène peut aussi être employée.

An 36 Personen wurden 100 ¹²⁵J-Natriumiothalamat- und endogene Kreatinin-Clearances bestimmt und mit gleichzeitig durchgeführten Inulin-Clearancebestimmungen verglichen. Der Urin-Plasma-Quotient zeigte eine sehr gute Korrelation zwischen je zwei der drei untersuchten Clearancemethoden, so daß beide Methoden, die nuklearmedizinische und die chemische, zur Bestimmung der glomerulären Filtration in der klinischen Praxis verwendet werden können. Der durchschnittliche ¹²⁵J-Natriumiothalamat/Inulin Clearance-Quotient betrug 1.01, der durchschnittliche endogene Kreatinin/Inulin Clearance-Quotient betrug 1.03. Es wird daraus geschlossen, daß die ¹²⁵J-Natriumiothalamat Clearance bei der klinischen Bestimmung des Glomerulusfiltrats die Inulin-Clearance ersetzen kann. In Zentren, die über keine Möglichkeit der Anwendung von Radioisotopen verfügen, kann stattdessen die endogene Kreatinin-Clearance verwandt werden.

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