Renal Clearance of [14C]oxalate: Comparison of Constant-Infusion with Single-Injection Techniques

1982 ◽  
Vol 63 (1) ◽  
pp. 47-51 ◽  
Author(s):  
J. A. C. Prenen ◽  
P. Boer ◽  
E. J. Dorhout Mees ◽  
H. J. Endeman ◽  
S. M. Spoor ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Renal Clearance ◽  
Single Injection ◽  
Compartment Model ◽  
Constant Infusion ◽  
Injection Technique ◽  
Clearance Ratio ◽  
Urine Sampling ◽  
Two Compartment Model ◽  
Infusion Technique

1. The renal clearance of [14C]oxalate was assessed by the constant-infusion technique and single-injection technique (plasma sampling only: one-compartment and two-compartment model; plasma and urine sampling). Healthy volunteers and patients with renal stones were studied. 2. Results with the constant-infusion techniques (with and without urine sampling) were not significantly different from each other. 3. The renal clearance of [14C]oxalate measured with the single-injection technique as compared with the constant-infusion technique was overestimated in the single-injection one-compartment model (52%) as well as in the two-compartment model (30%). 4. The calculated level of plasma oxalate in the healthy volunteers ranged from 1·04 to 1·78 μmol/l (mean 1·39). 5. The biological half-life of [14C]oxalate, estimated by the cumulative excretion of 14C in urine after equilibrium had been established, was 128 min (range: 113–142). 6. The oxalate/creatinine clearance ratio in the healthy volunteers ranged from 1·73 to 2·22 (mean 2·01).

Reassessment of the single intravenous injection method with inulin for measurement of the glomerular filtration rate in man

1991 ◽  
Vol 80 (2) ◽  
pp. 167-176 ◽  
Author(s):  
L. F. Prescott ◽  
S. Freestone ◽  
J. A. N. McAuslane
Keyword(s):  
Renal Failure ◽  
Healthy Volunteers ◽  
Renal Clearance ◽  
Single Injection ◽  
Linear Regression Analysis ◽  
Constant Infusion ◽  
Injection Method ◽  
Renal Clearances ◽  
Infusion Method ◽  
Total Body

1. Factors influencing the total body and renal clearances of inulin were investigated in a total of 37 healthy adult volunteers and 10 patients with stable chronic renal failure after the single intravenous injection of a dose of 70 mg/kg given over 5 min. 2. The elimination of inulin was highly concentration-dependent, and in healthy volunteers the renal clearance fell from 103.7 ± 14.4 ml min−1 1.73 m−2 during the first hour after administration to 49.1 ± 20.9 ml min−1 1.73 m−2 over the period 6-8 h. In the patients with renal failure the renal clearance fell correspondingly from 39.7 ± 16.5 to 26.6 ± 8.6 ml min−1 1.73 m−2. There were no changes in the simultaneously measured clearances of creatinine. 3. The values obtained for the total body clearance of inulin after a single injection depend critically on dose, the number and timing of blood samples, the choice of pharmacokinetic model, the number of data points chosen for estimation of the slope of the terminal elimination phase for analysis by the methods of residuals, and the weighting used for curve fitting by non-linear regression analysis. 4. With standardized conditions of sampling from 0 to 2 h and weighted non-linear regression analysis of the plasma concentration-time data, the total body and renal clearances of inulin were almost identical in subjects with normal renal function at 105.2 ± 10.2 and 102.9 ± 13.0 ml min−1 1.73 m−2. In the patients with chronic renal failure sampling was continued for 3 h and the corresponding clearances were 40.4 ± 15.3 and 38.9 ± 15.7 ml min−1 1.73 m−2. 5. The 0-2 h total body and renal clearances of inulin were measured by the single injection method and the renal clearance was measured by the standard constant infusion method on different occasions in 10 healthy volunteers. The respective clearances were similar at 101.4 ± 6.6, 94.9 ± 11.9 and 88.4 ± 12.1 ml min−1 1.73 m−2. 6. The reproducibility of the single injection and constant infusion methods was compared by measuring the inulin clearance with both techniques on three occasions in separate groups of eight and nine healthy volunteers. The mean coefficient of variation for the total body clearance with the single injection method was only 3.9% compared with 9.5% for the renal clearance determined the same way and 12.0% for the renal clearance during constant infusion. 7. Urine collection and fluid loading are not required for the single injection technique, and it is more reproducible and less demanding than the constant infusion method. With simple precautions, the single injection method with inulin is suitable for routine estimation of the glomerular filtration rate.

Simultaneous Measurement of Renal Clearance and Plasma Clearance of 99mTc-Labelled Diethylenetriaminepenta-Acetate, 51Cr-Labelled Ethylenediaminetetra-Acetate and Inulin in Man

1984 ◽  
Vol 66 (5) ◽  
pp. 613-619 ◽  
Author(s):  
M. Rehling ◽  
M. L. Møller ◽  
B. Thamdrup ◽  
J. O. Lund ◽  
J. Trap-Jensen
Keyword(s):  
Renal Function ◽  
Renal Clearance ◽  
Plasma Clearance ◽  
Single Injection ◽  
Close Correlation ◽  
Volume Of Distribution ◽  
Injection Technique ◽  
Clearance Ratio ◽  
51Cr Edta ◽  
Kinetics Of

1. The present investigation was undertaken to study the kinetics of 99mTc-labelled diethylene-triaminepenta-acetate (DTPA) as compared with inulin and 51Cr-labelled ethylenediaminetetra-acetate (EDTA). 2. Twenty patients with various degrees of decreased renal function were studied. The renal clearance, plasma clearance and volume of distribution of all three tracers were measured after a simultaneous single injection. 3. The average renal clearance ratio 99mTc-DTPA to inulin was 0.97; the average renal clearance ratio 99mTc-DTPA to 51Cr-EDTA was 1.02. 4. In all patients the plasma clearance of inulin exceeded that of 99mTc-DTPA. No difference was seen between the plasma clearance of 99mTc-DTPA and 51Cr-EDTA. The plasma clearance of all three tracers overestimated the simultaneously measured renal clearance; on average this was, for 99mTc-DTPA 5.7 ml/min, for 51Cr-EDTA 6.0 ml/min and for inulin 8.1 ml/min. The plasma clearance of 99mTc-DTPA correlated well with the renal clearance of inulin, but overestimated this by 3.5 ml/min on average. 5. The volume of distribution of inulin was less than that of 99mTc-DTPA and 51Cr-EDTA. No difference was seen between the volume of distribution of 99mTc-DTPA and 51Cr-EDTA. 6. It is concluded that the difference in the kinetics of 99mTc-DTPA and 51Cr-EDTA in patients with decreased renal function was small and without clinical relevance. The two radio-actively labelled tracers can replace each other in assessment of glomerular filtration rate (GFR). The close correlation between the plasma clearance of 99mTc-DTPA after a bolus injection and the renal clearance of inulin justifies the use of the single-injection technique in assessment of GFR.

scholarly journals The importance of the unsuppressed glands in the study of intact parathyroid hormone disappearance after parathyroid adenomectomy

2001 ◽  
pp. 353-362 ◽  
Author(s):  
F Locchi ◽  
M Tommasi ◽  
ML Brandi ◽  
D Borrelli ◽  
P Cicchi ◽  
...  
Keyword(s):  
Parathyroid Hormone ◽  
A Priori ◽  
Compartment Model ◽  
Constant Infusion ◽  
Intact Parathyroid Hormone ◽  
Theoretical Possibility ◽  
Ipth Level ◽  
Two Compartment Model ◽  
Disappearance Curve ◽  
Induction Of Anaesthesia

BACKGROUND: In the usual techniques for intraoperative intact parathyroid hormone (iPTH) monitoring for primary hyperparathyroidism, the normal glands are implicitly considered suppressed. On the contrary, we believe, as do other researchers, that they are not totally suppressed. METHODS: For this reason, we considered the introduction of an infusion from the unsuppressed normal glands (UNG), described by an influx constant (IC (pg/ml per min)), into the formulation of a two-compartment model. For the blood compartment, we have: C(t)=A.exp(-at)+B.exp(-bt)+EV, where A+B+EV=iPTH concentration at zero time (clamping), EV (equilibrium value)=IC/k, 'a' and 'b' are reciprocals of the time constants of the two exponentials and k=rate constant of elimination from the blood. The experimental data were obtained using an IRMA standard method, collecting samples in 20 patients, during and following adenomectomy. RESULTS: In spite of the variability among the patients, all fits were very good, thus confirming the importance of the UNG contribution to the shaping of the disappearance curve. For this reason, the relationship between the constant infusion from the UNG and the basal iPTH level at the induction of anaesthesia (BV), was studied. CONCLUSIONS: The existence of a negative correlation, together with the determination of a regression curve (IC=6.5BV), not only confirmed our assumptions, but also revealed the theoretical possibility of a priori knowledge of the iPTH contribution from the UNG. Hence, there is a theoretical possibility of discriminating between this contribution and that of the remaining (if any) affected gland(s).

Technetium‐99m‐MAG3 and technetium‐99m‐DTPA: Renal clearance measured by the constant infusion technique – Old news?

2021 ◽  
Vol 41 (6) ◽  
pp. 488-496
Author(s):  
Ann Mai Østergaard ◽  
Stine S. Langaa ◽  
Marie H. Vrist ◽  
Frank H. Mose ◽  
Jesper N. Bech ◽  
...  
Keyword(s):  
Renal Clearance ◽  
Constant Infusion ◽  
Technetium 99M ◽  
Infusion Technique

The Renal Clearance of Oxalate in Normal Subjects and Patients with Primary Hyperoxaluria

1971 ◽  
Vol 41 (3) ◽  
pp. 213-218 ◽  
Author(s):  
H. E. Williams ◽  
Gloria A. Johnson ◽  
L. H. Smith
Keyword(s):  
Oxalic Acid ◽  
Creatinine Clearance ◽  
Renal Clearance ◽  
Primary Hyperoxaluria ◽  
Normal Subjects ◽  
Constant Infusion ◽  
Clearance Ratio ◽  
Oxalate Concentration

1. The renal clearance of oxalate was studied in six normal subjects and in two patients with primary hyperoxaluria utilizing a constant infusion of [14C]oxalic acid. 2. The [14C]oxalate clearance in normal subjects was between 101 and 217 ml/min with a range in the ratio of [14C]oxalate clearance to creatinine clearance of 1.33–2.09. 3. The oxalate clearance in two patients with primary hyperoxaluria was within the range found in the normal subjects. 4. This study does not confirm the previous report of a low oxalate/creatinine clearance ratio in man nor the finding of an elevated oxalate clearance in patients with primary hyperoxaluria. 5. Estimates of serum oxalate concentration based on these clearance values suggest that the serum oxalate concentration in normal subjects is less than 100 μg/100 ml.

Pharmacokinetics and Effects on Fibrinolytic and Coagulation Parameters of Two Doses of Recombinant Tissue-Type Plasminogen Activator in Healthy Volunteers

1986 ◽  
Vol 56 (01) ◽  
pp. 001-005 ◽  
Author(s):  
M Verstraete ◽  
C A P F Su ◽  
P Tanswell ◽  
W Feuerer ◽  
D Collen
Keyword(s):  
Healthy Volunteers ◽  
Plasminogen Activator ◽  
Degradation Products ◽  
Plasma Concentrations ◽  
State Level ◽  
Compartment Model ◽  
Tissue Type ◽  
Maximum Plasma ◽  
Tissue Type Plasminogen Activator ◽  
Type Plasminogen Activator

SummaryPharmacokinetics and pharmacological effects of two intravenous doses of recombinant tissue-type plasminogen activator (rt-PA) (40 and 60 mg over 90 min) were determined in healthy volunteers. Mean maximum plasma concentrations were 1080 and 1560 ng/ml respectively. The steady state level during subsequent maintenance infusion of 30 mg over 6 h was 250 ng/ml. The pharmacokinetics of rt-PA showed a bi-exponential disappearance from plasma consistent with a 2-compartment model of t½α = 5.7 min, a t½β = 1.3 h and a total clearance of 380 ml/min.Mean fibrinogen levels at the end of the infusions of 40 mg or 60 mg rt-PA over 90 min, measured in thawed plasma samples collected on citrate/aprotinin, decreased to 74% and 57% of the preinfusion values respectively. Plasminogen fell to 55% and 48%, and α2-antiplasmin to 28% and 18% of initial values. No further decrease of these parameters was observed during the infusion of 30 mg rt-PA over 6 h. Only 2% of the preinfusion fibrinogen levels could be recovered as fibrinogen-fibrin degradation products. This moderate extent of systemic fibrinogenolysis is much less than that reported for therapeutic i.v. infusions of streptokinase.

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