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PubMed1997

Determination of glomerular filtration rate using technetium-99m-DTPA with differing degrees of renal function.

UNLABELLED: Glomerular filtration rate (GFR) is an important index of renal function. Twenty-four-hour creatinine clearance overestimates GFR in patients with poor renal function. Inulin and iothalamate clearances are accepted reference standards for determining GFR but are expensive and laborious. We have previously reported that GFRs obtained by measuring the disappearance of 99mTc-DTPA from ultrafiltered (protein-free) samples of plasma were virtually identical to those obtained by the iothalamate method. However, the subjects used in that study had normal to only moderately decreased renal function. METHODS: The accuracy of measuring GFR by plasma clearance of 99mTc-DTPA was determined in subjects where renal function varied from normal to severely impaired. In all subjects, GFR was established by clearance of 125I-iothalamate from urine and serum and was used as the standard of reference. RESULTS: For subjects with normal to moderately diminished renal function (GFR > 20 ml/min), the correlation between values of GFR obtained by the DTPA and iothalamate methods was high (n = 18, r = 0.966). The difference between the pairs of GFR values obtained by the two methods was not statistically significant (p > 0.1). In patients with severe renal insufficiency (GFR < 20 ml/min), the correlation between the DTPA and iothalamate methods was poor (n = 11, r = 0.236), and the GFR values obtained by the two methods were statistically different (p < 0.01). CONCLUSION: These results suggest that GFR can be determined accurately by plasma clearance of 99mTc-DTPA in all patients except those with severe renal insufficiency.

Adult↗
PubMed1997

Predictors of progression of diabetic nephropathy: implication for timing of kidney transplantation.

Multiple risk factors are important predictors in the development of diabetic nephropathy (DN). Once DN has developed, it progresses steadily to renal failure. To determine the rate of renal function decline and the parameters that influence the rate of decline, we retrospectively reviewed the charts of patients with DN who had undergone dialysis or kidney transplantation at the Mayo Clinic from 1983 to 1993. Forty patients were found to have two or more iothalamate clearance (IothmCl) measurements where a slope of renal function decline over time, expressed as mL/ min/month/1.73 m2, can be calculated. The parameters examined included age of onset and duration of diabetes (DM); age at initial presentation, insulin dosage, glycosylated hemoglobin level, proteinuria, blood pressure (BP), number of antihypertensive medications (HTM), use of ACE inhibitors, creatinine, and initial IothmCl. The mean overall decline of clearance was 1.36 +/- 1.1 mL/min/month, corrected. Univariate regression analysis showed that only systolic and mean BP (p < 0.05), use of HTM (p = 0.02), and the number of HTM used (p = 0.0001) correlated with the rate of clearance decline. No other parameter was significant. The decline of IothmCl was 0.72 +/- 0.41, 1.20 +/- 0.9, and 2.34 +/- 1.38 mL/min/month, for patients taking no HTM, < 3 HTM, and > or = 3HTM, respectively. Of the eight patients on HTM who presented with initial IothmCl of < 30 mL/min/1.73 m2, seven (88%) had clearance of < 10 mL/min/1.73 m2 within 1 yr. We conclude that hypertension is an important marker of DN progression, and that the more HTM required for control of BP, the faster the decline of renal function. We recommend that a suitable transplant candidate with DN who presents with hypertension requiring HTM and a clearance of < 30 mL/min should be placed on the transplant waiting list.

Adult↗
PubMed1976

[Paralysis following Dimer X radiculography].

The authors report four cases of cauda equina syndrome following Dimer X radiculography. The cases are described and commented upon. The conclusion is that Dimer X is a substrate associated with a certain degree of toxicity. Indications for and technique in sacroradiculography should be rigorous.

Adult↗
PubMed1997

Long-term renal function in heart transplant recipients receiving cyclosporine therapy.

BACKGROUND: Immunosuppression with cyclosporine has improved allograft function and reduced both morbidity and mortality in organ transplantation. However, cyclosporine-induced nephrotoxicity still is a concern. The purpose of our study was to evaluate the effects of cyclosporine on renal function in orthotopic heart transplant recipients. METHODS: Thirty-nine patients who received transplants from 1985 to 1991 and had at least three yearly glomerular filtration rate measurements posttransplantation by 125I-iothalamate clearance method were included in the study. In addition, serum creatinine (before and after transplantation) and cyclosporine doses were analyzed. RESULTS: Maintenance immunosuppression at 1 year consisted of prednisone (0.1 mg/kg/day), azathioprine (2 mg/kg/day), and cyclosporine (12-hour trough level 100 to 150 ng/ml by fluorescence polarization immunoassay). The mean serum creatinine at 1 year was significantly higher than the mean pretransplantation serum creatinine (1.51 +/- 0.32 versus 1.28 +/- 0.38, p < 0.05) and stabilized after the first year. The mean glomerular filtration rate by 125I-iothalamate clearance method was 70.6 +/- 20.3 ml/min/1.73 m2 (range 32 to 105) at 1 year and remained relatively stable during the follow-up period of up to 7 years. Creatinine clearance calculated by the Cockcroft and Gault formula overestimated the true glomerular filtration rate after the third year. The mean cyclosporine dosage was significantly lower after the first-year dose of 3.9 +/- 1.8 mg/kg/day (p < 0.05). Three patients in 39 started hemodialysis at 5, 7, and 10 years after transplantation. CONCLUSION: Our data indicate that the adequacy of renal function is preserved with long-term cyclosporine therapy in heart transplant recipients.

Adolescent↗
PubMed1998

Assessment of PD treatment delivered by 125I-Iothalamate plasma disappearance.

The calculation of treatment delivered to PD patients requires the collection of PD effluent, plasma and urine samples. 125I-Iothalamate plasma disappearance, which eliminates the need for PD effluent collections, was tested as an alternate method to measure the weekly PD treatment delivered. Two protocols were designed. In protocol A, a 35 microCi dose of 125I-Iothalamate was injected in three subjects and allowed to equilibrate. A plasma sample was taken and patients returned on both of the following two days with timed labeled effluent bags and a 24-hour urine collection for each day. The timed PD effluent and 24-hour urine collections were measured for 125I-Iothalamate, urea and creatinine concentrations. 125I-Iothalamate and urea clearances were strongly correlated for both PD (R2 = 0.76, n = 24) and renal (R2 = 0.92, n = 6) clearances. In protocol B, thirteen subjects were given a 35 microCi injection of 125I-Iothalamate. A blood sample was taken one hour post injection and a second blood sample taken on day five. Kt/V were calculated from the 125I-Iothalamate plasma disappearance curve and compared to weekly Kt/V values extrapolated from one day's collections (Traditional Method). The comparison of Kt/V values found by 125I-Iothalamate Method vs. the "Traditional Method" yielded R2 = 0.79, n = 13. In conclusion, the plasma disappearance of 125I-Iothalamate is an alternate method of determining weekly Kt/V, over an extended period of time, which eliminates the need for PD effluent collections.

Creatinine↗
PubMed1976

[A new contrast-medium (author's transl)].

Infusion urograms were carried out on 2 groups of 100 in-patients each. The first group had injections of Conray FL 36, the second of Conray FL. Contrast in the early phase after 7 minutes was better with Conray FL 36 than with Conray FL. At later stages there was no clear difference.

Humans↗
PubMed1976

[Concentration of contrast medium in xerophlebography (author's transl)].

We examine with phlebography usually a damaged vascular system. Radio-contrastmedia damage vascular endothelium. If we dilute them we may minimize the damaging effect. But when using the usual film-foliae combination, diagnostic results diminish the more we dilute. Results of 31 comparative investigations with film and xerphlebography show that dilution of contrast medium to 50 or even 25% will still produce phlebograms sufficient for evaluation with xerophlebography. It also has the advantage of a large picture: soft parts, veins and bony structures are visible of the same time. At present the method (chance of screening, gaps) renders routine use not advisable.

Humans↗
PubMedDate not supplied

Evaluation of renal functions in children with congenital heart disease before and after cardiac angiography.

Radiocontrast nephrotoxicity, which has increased in incidence with widespread use of radiological methods in medicine, is a serious complication of radiocontrast materials. In this study, we have prospectively investigated whether children with cyanotic congenital heart disease are at risk for radiocontrast nephrotoxicity with the use of a nonionic low osmolar contrast agent. Thirty-five children (17 cyanotic and 18 acyanotic patients) who underwent diagnostic cardiac catheterization were subjects of the study. The age range was from five days to 13 years. The volume of contrast material was 3.11 +/- 1.37 ml/kg in cyanotic patients and 2.67 +/- 0.86 ml/kg in acyanotic patients. Blood samples and timed urine samples were taken from all patients 24 hours before and 48 hours after cardiac catheterization. Blood urea nitrogen, creatinine, sodium, and phosphorus in serum, and creatinine and N-acetyl-beta-D-glucosamine in urine were analyzed. There was not a statistically significant difference between the values before and after angiography. As a result, we could find no evidence of radiocontrast nephrotoxicity with the use of a nonionic contrast agent in cyanotic and acyanotic patients who underwent cardiac angiography.

Adolescent↗
PubMed1976

[Side reaction after lumbar myelography with dimer-x (author's transl)].

The existence of several very impressive spinal paroxysms after lumbar myelography with Dimer-X1 caused us to make a retrospective investigation of 327 patients with 355 myelographies. In 7.1% of the investigations we have found partly heavy, but mostly reversible neurological complications. The latter cannot be classified, contrary to prevailing statements, in spinal, meningeal or cerebral reactions, since mostly all 3 anatomical structures are being concerned. Corresponding casuistical information are being presented and with their neurological symptomatic discussed. The spinal paroxysms appeared approximately 6 hours after the myelography and lasted over 8-10 hours, in spite of intensive therapeutical efforts. The pathogenesis points to a multifactorial occurrence caused by the coincidence of an increased dosage of the contrast media, too bed rest time, rising of the contrast media in the spinal cord zone and disturbed liquor fluid circulation and contrast media resorption. Pathophysiologically is in connection with spinal cramps an epileptic mechanism probable. Additional spinal reflexive components could be an explanation for the little therapeutical effect of Diacepam (Valium), which is contrary to the statement in the literature. We have seen a better effect in particular cases with Phenothiazine. With strict observance of specific precautionary measures, the Dimer-X seems to be a good media for the presentation of the lumbar subarachnoid space. A further development in this field is desirable.

Adolescent↗
PubMedDate not supplied

New media. Particulate contrast media.

Particulate contrast agents, when compared to water-soluble media, offer the advantage of allowing the administration of high doses without creating hypertonicity gradients and ionic imbalances. Since these radiopaque particles are accumulated in the reticuloendothelial system, they could be ideal hepatic CT contrast agents. We have developed a method for making particles of 2 +/- 1 microns by precipitating from an organic solvent. Preincubation of these particles in human serum albumin overcomes the very serious problem of in vivo particle aggregation and embolization. The ethyl esters of iothalamic and iodipamic acid have been injected intravenously into mice, rats, and rabbits. Radiopacification of the liver is maximal within 2-3 hours postinfusion, with radiopaque material subsequently clearing through the biliary system. Elimination from the organism seems to be complete within a few days postinfusion. Efforts to decrease the subacute toxicity of these agents are underway.

Animals↗
PubMed1992

Renal scanning 99mTc diethylene-triamine pentaacetic acid glomerular filtration rate (GFR) determination compared with iothalamate clearance GFR in diabetics. The Collaborative Study Group for The study of Angiotensin-Converting Enzyme Inhibition in Diabetic Nephropathy.

Traditionally, creatinine clearance is used as an estimation of the glomerular filtration rate (GFR) because of its relative ease and low cost. Errors in collection limit its usefulness. Estimation of GFR using 99mTc diethylene-triamine pentaacetic acid (Tc-DTPA) by direct scintigraphic determination of fractional radionuclide accumulation within each kidney does not require blood or urine sampling, takes 10 to 15 minutes to perform, and has been reported to give a GFR that correlates with 24-hour urinary creatinine clearance (CC) in hospitalized patients (r = 0.95). To assess its usefulness in the outpatient diabetic with nephropathy, 24 patients with type I diabetes underwent 56 iothalamate clearances during water diuresis and 56 simultaneous Tc-DTPA GFR estimations. GFR was also estimated from 24-hour urinary CC, 100/creatinine, and by the formula of Cockcroft and Gault. Tc-DTPA GFR estimation by direct renal scanning correlated relatively poorly with iothalamate GFR (r = 0.74) in this patient population when all levels of iothalamate GFR were compared (n = 56), but improved (r = 0.80) when iothalamate GFR values greater than or equal to 120 mL/min were excluded from analysis (n = 45). Given all levels of iothalamate GFR, the best correlation was obtained with the estimation using the equation of Cockcroft and Gault (r = 0.86).

Adult↗
PubMed1990

Inhibition of intermediary metabolism by amiodarone in dog thyroid slices.

Amiodarone, an iodine-containing antiarrhythmic drug, has been reported to interfere with thyroid function and thyroid hormone metabolism. We studied the effects of amiodarone on basal and agonist [thyroid-stimulating hormone (TSH), phorbol ester, or carbachol]-stimulated glucose oxidation, 32PO4 incorporation into phospholipids, and adenosine 3',5'-cyclic monophosphate (cAMP) concentration in dog thyroid slices. Slices were preincubated with amiodarone at 37 degrees C for 1 h before the addition of agonist and the appropriate radioisotope. cAMP stimulation was measured after 20 min, glucose oxidation for 45 min, and 32PO4 incorporation into phospholipids for 2 h. Amiodarone (0.5 mM) had no effect on basal 14CO2 formation or 32PO4 incorporation into phospholipids but significantly inhibited TSH, phorbol ester, and carbachol stimulation of these parameters. It also inhibited cAMP stimulation by TSH. Inhibition of TSH-stimulated [14C]glucose oxidation was also obtained with another iodide-containing compound, iopanoic acid (0.5 mM), but not with iothalamate (up to 10 mM). Inhibition by amiodarone was still present, but to a lesser extent, when it was added at the same time as the agonist. Inhibition of stimulated [14C]glucose oxidation persisted even after the slices were incubated without amiodarone for 6 h. Inhibition by amiodarone, in contrast to that by inorganic iodide, was not prevented by 1 mM methimazole added at the same time as amiodarone. These results indicate that the inhibitory effects of amiodarone on thyroid function are not due to dissociation of iodide from the molecule.

Amiodarone↗
PubMed1985

Renal tubular accumulation of organic substances: a new in vivo method which differentiates between luminal and peritubular uptake.

Using a modification of the Sperber technique we studied cellular uptake of organic substances in the kidney. A test substance was mixed with an extracellular marker (ethylenediaminetetraacetate or inulin), both radiolabelled with an activity ratio close to I, and injected into the renal portal system on one side via a leg vein. The animals were killed 1-10 min after injection and the radioactivity in different organs determined. Results showed significantly higher ipsilateral (injection) to contralateral (control) kidney ratios (substance to marker) at 1 min after injection for 125I-Na-o-iodohippurate (125I-Hipp; P less than 0.001), 14C-tetraethylammonium bromide (14C-TEA; P less than 0.001), 3H-dihydromorphine (3H-DHM; P less than 0.01), and 125I-iothalamate (P less than 0.01), with a progressive decrease in injection kidney ratios for 125I-Hipp and 14C-TEA when death occurred after a longer period. Inhibition of renal tubular transport with novobiocin or mepiperphenidol markedly reduced 1- and 4-min injection kidney ratios for 125I-Hipp and 14C-TEA, respectively. When death occurred after a longer period, ratios in both kidneys increased significantly for 125I-iothalamate. A good correlation was found between peak cellular accumulation in the kidney and excretion efficiency of test substances. Thus, the results indicate that 125I-Hipp, 125I-iothalamate, 14C-TEA, and 3H-DHM were accumulated from the peritubular side of the nephron through the transport systems for organic acids and bases, respectively, and that 125I-iothalamate also showed luminal uptake. In conclusion, this new in vivo technique is simple and well suited for studying renal tubular accumulation of organic substances and offers the advantage of being able to distinguish luminal from peritubular uptake.

Animals↗
PubMed1997

GFR determined by nonradiolabeled iothalamate using capillary electrophoresis.

Traditional measurements of glomerular filtration rate (GFR) in clinical practice include the measurement of serum creatinine or creatinine clearance. Increasing evidence concerning the limitation of these measurements in clinical practice and clinical trials has resulted in efforts to develop technologies that improve measurement of GFR. Recent efforts in that regard have used radioisotopic labeling of markers of GFR, such as 125I-iothalamate, and 51Cr-ethylenediaminetetraacetic acid. Limitations of these technologies include radiation exposure as well as cost considerations for the management of radioisotopes, including safety, disposal, mailing, and deteriorating activity that results in short shelf life. We report a test that used 0.5 mL Conray dye injected subcutaneously and subsequent measurement of the nonisotopic (cold) iothalamate by capillary electrophoresis in blood and urine. GFR using cold iothalamate compared with standard clearance using 125I-iothalamate was 0.99. The method is cost-effective and allows for avoiding exposure to isotopes, as well as problems such as the disposal and short shelf life of isotopes. This technology could allow for replacement of 125I-iothalamate as a marker for GFR.

Adolescent↗