Clearance, normal values

This antibody is raised against the protein-based CD3 antigen, present on the cell surface of most T-lymphocytes. I.v. administration of (unconjugated) antibody appears to block normal functioning of such T-cells and promote their clearance from the blood. However, upon cessation of antibody administration, CD3 positive cell numbers rapidly revert to normal values. Therefore, maintenance immunosuppressives (e.g. with cyclosporine) must subsequently be restored. 

Opiates can effect serum levels of enzymes and other substances whose homeostatic control depends on clearance through the liver (F8, G12, M15, N4, S19). In one reported case, the aspartate aminotransferase was within normal limits before the administration of codeine, but within 2 hours after the drug, the enzyme activity had risen to two times the normal value by 8 hours to eight times the normal activity, and within 24 hours it had returned to normal (F8). Increases in transaminase to levels 5-85 times the control value have been reported in 6 of 16 patients with disease of the biliary tree following the administration of codeine phosphate (2 grains) (B7, F8). Gross has shown that morphine, codeine, or mepheridine administration produce elevations of serum amylase or lipase (G12). These elevations have been attributed to constriction of the sphincter of Oddi and increased intraductal pressure on the pancreatic duct (G12, N4). 

The maintenance within a recognizable range of the serum enzyme activities implies some similarity between their rate of discharge from the tissues into the blood stream and the rapidity of their clearance from it. This clearance can be exceedingly swift, though confronted by skeletal muscle of which 300 mg contains as much aldolase as the entire adult circulation (S22). After the intravenous injection of crystalline aldolase in rats the activity of the serum aldolase rises 7-fold in the first 15 minutes, but 12 hours later has fallen to only 1.5 times the normal value (S24). Further, the intravenous injection in rabbits of pure crystalline aldolase labeled with and the measurement of the rate of disappearance of radioactivity in successive serum specimens indicate... 

PAH is an organic anion that has been used extensively for the quantitation of renal plasma flow. PAH is approximately 17% bound to plasma proteins and is eliminated extensively by active tubular secretion. Because PAH elimination is active, saturation of the transport processes have historically been anticipated, at concentrations of PAH in plasma above 10 to 20 mg/L. Recently, Dowling and associates used a sequential infusion technique and only observed concentration-dependent renal clearance of PAH at concentrations above 100 mg/dL. Furthermore, PAH is also metabolized, possibly within the kidney, to A-acetyl-PAH, and the analytical method must be able to differentiate the parent compound from the metabohte if one desires to obtain an accurate assessment of RPF. Prescott and coworkers noted that the renal clearance of PAH alone decreases at low plasma concentrations, while the clearance of the acetyl metabolite increases. Further studies are necessary to evaluate the mechanisms and significance of these findings. The extraction ratio (ER) for PAH is 70% to 90% at plasma concentrations of 10 to 20 mg/L, hence the term effective renal plasma flow (ERPF) has been used when the clearance of PAH is not corrected for the extraction ratio or if it is assumed to be 1. Normal values for ERPF are about 650 160 mL/min for men and 600 150 mL/min for women. Children will reach normahzed adult values by 3 years of age, and ERPE will begin to decline as a function of age after 30 years, reaching... 

A a absorption rate constant k elimination rate constant koD. elimination rate constant during dialysis KF ratio of the patient s creatinine clearance to the assumed normal value of 120 mL/min... 

Sometimes, rather than treating the covariate as a continuous variable, the covariate will be categorized and the categorical variable will be used in the model instead of the original value. For example, de Maat et al. (2002) in a population analysis of nevirapine categorized baseline laboratory markers of hepatic function into dichotomous covariates. Patients were coded as V if their laboratory value was 1.5 times higher than the upper limit of normal and 0 otherwise. Patients with an aspartate aminotransferase 1.5 times higher than normal had a 13% decrease in nevirapine clearance than patients with normal values. 

Thyroid Gland Disorders. The elimination half-life of theophylline is markedly prolonged in hypothyroidism. Conversely, clearance is increased in hyperthyroidism, but reduces toward normal values after initiation of treatment for this disorder. ... 

Creatinine clearance (Cld) is renal clearance (Cl,) applied to endogenous creatinine. It is used to monitor renal function and is a valuable parameter for calculating dosage regimens in elderly patients or those suffering from renal dysfunction. Normal creatinine clearance (Clc) values are ... 

Normal value is 32.34Lh . Note that systemic clearance of procainamide in this... 

Heylmeyer and associates. After 7 years, patients with hypochromic anemia, low levels of iron and transferrin in blood, had increased iron stores in liver, spleen, and bone marrow. The total binding capacity of the plasma for iron was markedly reduced, and the ability of the plasma to transport iron was far below normal since the half time for clearance of radioactive iron from the plasma had fallen to less than 0.1 of the normal value. 

The viscosity in the clearance ij. is differentiated from the viscosity in the channel j, because, in reality, the viscosity in the clearance will be substantially different from the viscosity in the channel as a result of differences in local temperature and shear rate. When the flight clearance is close to the normal design clearance, the value of 4 will be very close to zero and can be neglected unless extreme accuracy is required. However, when the radial clearance is considerably larger than the normal design clearance, for instance, as a result of wear, the actual value of fL should be used in the expression for the total volumetric output, Eq. 7.224. 

The difference between Eqs. 7.228 and 7.224 is less than 5% at normal values of the clearance and about 10% at clearance values of about four times the normal value. 

For normal values of the flight clearance, however, Eq. 7.228 will generally give sufficiently accurate results. 

D) is about 0.01% of the drag flow rate at four times the normal clearance, the leakage flow is about 1% of the drag flow rate. Thus, the leakage flow becomes significant only when the clearance is larger than about four times its normal value. 

The direct measurement of clearances normalized to body surface area and body water volume, expressed on a weekly basis, is crucial in the assessment of treatment adequacy. Creatinine and urea clearance are the most widely used adequacy indices in PD and APD. In a steady state, the calculation of clearance, that is, the ratio between dialytic (and renal) solute removal and blood solute concentration, requires quantitation of solute removed by total collection of drained dialysate. Blood and dialysate solute concentrations are measured by standard assays. The ratio of dialysate to blood solute concentration multiplied by the dialysate volume equals the clearance (Van Stone 1989). In APD, the intermittency or variable intensity of the therapy causes a modest compartmental disequilibrium with fluctuation of plasma concentrations between the predialytic (evening) and postdialytic (morning) values (Newman 1995, Calconi 1998). This difference is more marked for urea than for creatinine (Newman 1995). 

The intrinsic clearance of an organ is different from the value we normally think of as the clearance of the organ. The clearance of the organ is defined as the rate of loss in relation to the incoming concentration, whereas the intrinsic clearance is defined as the rate of loss in relation to the organ concentration (or exiting concentration). In addition, it is also clear that, of the... 

A substance that fulfills these criteria is para-aminohippuric acid (PAH). All of the PAH not filtered at the glomerulus is secreted by the proximal tubule. The net effect is that all of the plasma flowing through the nephrons is completely cleared of PAH. It is important to note that about 10 to 15% of the total renal plasma flow supplies regions of the kidneys that are not involved with filtration or secretion. Consequently, this plasma cannot be cleared of PAH. Therefore, the plasma clearance of PAH provides a measurement of the effective renal plasma flow, that is, the volume of plasma that actually flows through the nephrons. The ERPF is normally about 625 ml/ min. (This value is based on a renal blood flow of about 1.1 1/min and a hematocrit of about 42.)... 

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