The Use of Radioactive Compounds for Evaluating Liver Function

Abstract

SummaryThree radioactive compounds (I-131 iodipamide, I-131 glyceryl trioleate, intravenous emulsion, Fe-59 EDTA) have been tested to determine whether or not they discriminate the normal from the abnormal liver. The procedure for all three compounds was similar. Hospital patients were transported to the radioisotope laboratory and scintillation detectors placed over their hearts and livers with the patients in supine position. 5 to 20 microcuries of the various radioactive compounds were injected intravenously and the hepatic and cardiac radioactivity recorded by means of count ratemeters and recorders for time intervals from 10 to 30 minutes. At 2- or 3-hour intervals after this injection blood samples were withdrawn so that plasma radioactivity could be determined. Urine collections were made at 3- or 4- and 24-hour intervals for determining the fraction of the administered dose excreted by the kidneys.The results of these various procedures were analyzed for possible statistical differences between patient groups. For the iodipamide and glyceryl trioleate intravenous emulsion studies the classification was merely patients with and without liver disease. Because of the preponderant renal role in the excretion of chelate, the patients in this series were further divided into those without liver or renal disease, with liver disease, with renal disease, and with both liver and renal disease. This differentiation was made on the basis of clinical and routine laboratory examinations.Statistical differences between groups with and without liver disease were noted for nearly all procedures for each of the compounds.Because the hepatic tracing of radioactivity for the iodipamide procedure is highly discriminating between the normal and abnormal liver and the curve is easily interpreted, this would appear to be the procedure of choice for this compound. To obtain the most information from this tracing for the glyceryl trioleate intravenous emulsion and Fe-59 EDTA, a semilogarithmic plot of the data was necessary. The excretory portion of these curves were significantly decreased in patients with liver disease. The semilogarithmic plots of the data from patients to whom Fe-59 EDTA was administered routinely resolved into two linear curves. Analysis of the data indicated that the first and more rapid of these was due to hepatic function and the second slower portion to urinary excretion.It is thought that the iodipamide is dependent upon hepatic uptake; the glyceryl trioleate intravenous emulsion, on hepatic lipid metabolism; and the Fe-59 EDTA, upon some possible metabolic alteration of the molecule and/or competition and exchange of radioactive iron with physiologic chelates.