Preparation and Use of I131 Labeled Sodium Iodohippurate in Kidney Function Tests

Abstract

Introduced by A. L. Sellers)There is need for a rapid and non-traumatic method for assessing individual kidney function. Use of labeled compounds and external radioactivity measurements over the kidneys appear quite adequate for the purpose. After injection, uptake and clearance by each kidney are measured by means of radioactivity, producing a printed record by use of appropriate instrumentation ( 1 ) . However, the methold used previously was complicated because the diethanolamine salt of 1131 labeled 3,5-diiodo-4-pyridone-N-acetic acid (Diodrast) was not kidney-specific and because of its hepatic uptake, required careful placement of the probes ( 2 ) . In addition, labeled analogs of sodium 3,5-diacetamido-2, 4,6-triiodobenzoate (Hypaque) , methyl-glucamine 3 , 5 -diace tamido-2,4,6-triiodobenzoa te (Renografin) , sodium 3-acetamido-2,4,6-triiodobenzoate (Urokon) , and sodium 3,5dipropionylamino-2,4,6-triiodobenzoate ( Miokon), all have the disadvantage oif being cleared slowly by the kidneys, prolonging test time to 15-25 minutes. Although they are essentially noit picked up by the liver, they differentiate less clearly the function of the individual kidneys. Theoretical considerations indicated that sodium o-idohippurate (Hippuran) had the desired characteristics folr comparing separate kidney function, namely rapid and complete removal frolm the blood by the kidneys only. This compound containing I*"* was then prepared by the 2 methods described and proved quite satisfactory for the purpose.Methods. Hippuran containing was prepared by 2 methods of exchange. In Method I , ca. 20 mc was released from N a P solution (Oak Ridge) by 0.33 ml 0.01 M KI, 0.1 ml M NaN02 and 0.2 ml 2.5 Ril:HCI and the iodine shaken out with 2 ml K l $ . The shakeout wits repeated with the same quantities of reagents but no IJ;{l. The combined CC14 solutions of were washed by shaking with 2 ml H20, then extracted with 0.5 ml H20 plus 0.6 ml 0.1 bf NaOH followed by 0.5 ml H20 plus 0.2 ml 0.02 M NaOH.The N a F solutions were added to 363 mg Hippuran dissolved in 2 ml H20 in 10 ml serum vial and adjusted to pH 6 with 0.1 M HCl and pH paper. The vial was closed with rubber stopper covered on underside with Saran film, sealed with aluminum seal and heated 2 hours in boiling water. The contents were transferred tc 201 ml beaker and evaporated to dryness, redissolved in 1 ml boiling H20 and transferred to 1 2 ml centrifuge tube. The o-iodohippuric acid was then precipitated with 0.6 ml (1 + 9) HCI, centrifuged 2500 rpm/lO min., the supernate removed, the precipitate dissolved in ca. 4.5 ml boiling H20, 1 mg K I in 0.1 ml H20 added and solution cooled in ice water and centrifuged. The precipitate was transferred using a minimum amount of supernate to a small sintered glass filter: washed with small polrtions of ice-cold saturated solutioin of non-radioactive o-iodohippuric acid and dried to constant weight a t 100". The yield was 55% of the weight of Hippuran taken and specific activity 49 pc/mg. The m.p. was 173.5" (corr.), which differed fr...

First experience in healthy volunteers with technetium-99m l,l-ethylenedicysteine, a new renal imaging agent

“…As none of the atoms of PAH can be replaced by a suitable 7-emitting radioisotope, Tubis and co-workers developed in 1960 a radioiodinated derivative of PAH, o-iodohippurate (OIH, hippuran) [1]. OIH, labelled with 123I, 12sI or 1311, has since become the standard radiopharmaceutical for the radioisotopic measurement of effective renal plasma flow (ERPF).…”

Monoanionic 99m Tc-tricarbonyl-aminopolycarboxylate complexes with uncharged pendant groups: Radiosynthesis and evaluation as potential renal tubular tracers

“…The accuracy of scan interpretation and camera-based measurements of renal function are optimized by a high renal extraction efficiency, providing a rapid renal clearance and high target-to-background ratio. Because only 20% of renal plasma flow in humans is filtered, the extraction efficiency of glomerular filtration rate (GFR) tracers such as 99m Tc-diethylenetriaminepentaacetic acid ( 99m Tc-DTPA) cannot be greater than 20%; consequently, to achieve a high extraction efficiency, it is necessary to design new tracers that are extracted by the renal tubules in a manner similar to that for 131 I-o-iodohippurate ( 131 I-OIH), the radioactive standard for the measurement of effective renal plasma flow (ERPF) [1–3]. 99m Tc-based renal agents have attracted the most interest owing to the widespread availability of 99m Tc and its superior nuclear medicine properties ( t 1/2 = 6 h, 140 keV γ-radiation) over the beta emission, 8-day half-life and 364 keV photon of 131 I.…”

Nuclear Medicine and Radiochemistry

“…The radiodiagnostic preparation should be selectively accumulated by the organs or systems whose scintigrams are to be recorded or whose function is to be tested, since the radiation of radioactive material concentrated elsewhere interferes with the measurement. 4. To avoid chemical noxae, radiodiagnostic preparations whose residence time in the body is short, i.e.…”