PubMed · 1102194
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B E Christensen. 1975. Red cell kinetics.. https://pubmed.ncbi.nlm.nih.gov/1102194/
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Glomerular filtration rate (GFR) was measured in two groups of cancer patients. In 20 patients, glomerular filtration rate was measured simultaneously with 51Cr-EDTA, 99mTc-DTPA and the X-ray contrast agent iohexol as markers, and with a complete set of eight blood samples during 24 hours. In a second group of 120 patients, we used 99mTc-DTPA only and tested various simplified methods, based on one or two blood samples. Glomerular filtration rate was also calculated from serum creatinine. There was excellent agreement between the values measured with the three markers, and, in the same group of patients, very good agreement with the results of simplified methods. The larger study carried out with 99mTc-DTPA on the second group of patients, confirmed a very good agreement between methods based on the slope of the plasma curve and a method based on one blood sample only. The correlation was worse between the values obtained by any of the radionuclide methods and those calculated from serum creatinine. The latter method should therefore not be used for determination of renal function.
Chronic stress causes multiple biochemical and physiological changes in the human organism. Recently we have identified stressin, a human serum glycoprotein that was significantly increased in sera of prisoners released from Serbian concentration camps. To eliminate malnutrition and maltreatment as possible causes for the increased stressin concentration, we have analyzed stressin in sera of 40 professional soldiers after involvement in major military activity and compared it to stressin in sera of 20 control individuals. As expected, the sera of professional soldiers contained more than 2.2 times higher concentrations of stressin than control sera. It is interesting that, contrary to expectations, the natural killer cell activity of professional soldiers was normal or even increased. We hypothesize that this might be an effect of winning the war that could have, at least temporarily, erased the immunosuppressive effects of stress.
Plasma clearance of 51Cr-EDTA is widely used to assess the glomerular filtration rate (GFR) in diabetic nephropathy. Originally, the ratio between the intravenously injected amount of tracer and the total area under the plasma concentration curve was used for the calculation of total 51Cr-EDTA plasma clearance (C(T)). Simplified methods, using the final mono-exponential part of the plasma curve, have been suggested, e.g. four samples, taken 180 to 240 min after injection (C(IV)), or using one sample taken at 240 min (C(I)). Our aim was to evaluate the agreement between measurements of GFR and rate of decline in GFR based upon these three methods. Bland & Altman plots were used to illustrate the range of agreement. We investigated 76 insulin-dependent diabetic (IDDM) patients with microalbuminuria or diabetic nephropathy. GFR was measured after a single intravenous injection of 3.7 MBq 51Cr-EDTA by determining the radioactivity in venous blood samples taken 5, 7, 10, 15, 30, 45, 60, 90, 120, 150, 180, 200, 220, and 240 min after the injection. Rate of decline in GFR was assessed using 12 (6-17) determinations of GFR over a period of time of 8 (4-10) years. Mean (SD) GFRT was 123 (21) ml x min(-1) compared to GFR(IV) 123 (21) ml x min(-1) (NS) and GFR(I) 115 (17) ml x min(-1) (p < 0.00001). The mean difference (95% limits of agreement) between GFR(T) and GFR(IV) was +0.6 (-16.6 to +17.7) ml x min(-1), and between GFR(T) and GFR(I) +8.0 (-6.0 to +22.2) ml x min(-1). The difference between GFR(T) and GFR(I) was significantly correlated with their mean value (r = 0.56, p < 0.00001), indicating increasing underestimation by GFR(I) with increasing GFR levels. The mean (SD) rate of decline in GFR(T) was 2.3 (3.9) ml x min(-1) x year(-1), compared to a mean rate of decline in GFR(IV) of 2.4 (3.6) ml x min(-1) x year(-1) (NS), and a mean rate of decline in GFR(I) of 2.2 (3.5) ml x min(-1) x year(-1) (NS). The mean difference (95% limits of agreement) between rate of decline in GFR(T) and rate of decline in GFR(IV) was +0.16 (-1.59 to +1.91) ml x min(-1) x year(-1), and between rate of decline in GFR(T) and rate of decline in GFR(I) -0.01 (-1.64 to +1.61) ml x min(-1) x year(-1), respectively. In conclusion, our cross-sectional study revealed a close agreement between GFR(T) and GFR(IV) with acceptable limits of agreement (precision), while GFR(I) lacked accuracy. However, a close agreement between rate of decline in GFR(T) and rate of decline in GFR(IV), and between rate of decline in GFR(T) and rate of decline in GFR(I), with acceptable limits of agreement (precision), suggests that both simplified methods are applicable for long-term follow-up.