The following medications have been shown to falsely elevate serum creatinine: 12 , 20 , Certain patient groups have dramatically different serum creatinine production or elimination compared to the normal patient population.
The following groups are notoriously difficult to estimate true renal function:. There are primarily two laboratory methods for measuring serum creatinine: a number of conventional older methods eg, alkaline picrate , and the newer IDMS method. You may specify whether you are entering serum creatinine as an IDMS or 'conventional' assay by clicking the 'Advanced Settings' button beneath the 'Calculate' button.
Show AMA citation. IDMS is the newer, more precise method for measuring serum creatinine. Most institutions are using IDMS by this point, but you should contacting your laboratory if you are unsure of your assay. For more information, read more about IDMS. OK Clear. Advanced Settings. US units. Press 'Calculate' to view calculation results. Load an Example.
Prediction of creatinine clearance from serum creatinine. PMID A new equation to estimate glomerular filtration rate.
Ann Intern Med. Jelliffe RW. Letter: Creatinine clearance: bedside estimate. Predicting creatinine clearance and renal drug clearance in obese patients from estimated fat-free body mass.
Am J Med. National Kidney Foundation. Am J Kidney Dis. Using standardized serum creatinine values in the modification of diet in renal disease study equation for estimating glomerular filtration rate. A more accurate method to estimate glomerular filtration rate from serum creatinine: a new prediction equation. A computer program for estimation of creatinine clearance from unstable serum creatinine levels, age, sex, and weight.
Mathematical Biosciences. DOI A new simple and rapid method to monitor the renal function based on pharmacokinetic consideration of endogeneous creatinine. Res Commun Chem Pathol Pharmacol.
Influence of renal function and dialysis on drug disposition. Chow MS, Schweizer R. Estimation of renal creatinine clearance in patients with unstable serum creatinine concentrations: comparison of multiple methods.
Drug Intell Clin Pharm. The Cockcroft-Gault equation estimates creatinine clearance and incorporates weight into the equation. As a result, an individual patient may have very different renal function estimates, depending on the equation used. We now highlight these differences and discuss the impact on routine clinical care for anticoagulation to prevent embolization in atrial fibrillation.
Chronic renal failure is a public health problem worldwide; over the last few years the incidence and prevalence of renal disease has increased. This increase may be the result of greater progression of chronic renal failure, of greater treatment availability and of the decrease of mortality. It is estimated that in , in the USA, the number of people with kidney disease treated by dialysis or renal transplant will increase from , to , Additionally, currently in the USA the prevalence of early stages of renal failure is greater than the prevalence of advanced renal disease Due to all the above, it is very important to detect any renal function deterioration and begin treatment to delay the progression of renal damage.
Inulin has been, since its introduction, the ideal substance to measure glomerular filtration, since it is a compound that complies with all the requirements for the ideal marker; however, its clinical application is not practical.
Therefore, for a long period of time, serum creatinine has been used despite the fact that its values also depend on muscular mass, age, sex, variable absorption and tubular secretion. Furthermore, its measurement may be altered by chromogens. GFR may be estimated using equations such as the Cockcroft- Gault formula and the abbreviated equation of the MDRD study, but any formula using levels of serum creatinine will depend on calibration and variability of the method used for its measurement.
The formula derived from the MDRD study has been assessed in different studies and has shown contradictory results in the different groups studied. Furthermore, it is less precise in healthy patients, diabetic patients without proteinuria and patients with renal failure but with normal levels of serum creatinine. This has been shown to be a reliable marker of renal function, compared with inulin, and it is mainly used for research; however, this marker is not currently available in our institution.
Furthermore, the results of technetium clearance have been compared with iothalamate clearance, and show an adequate correlation. We used short periods for urine and blood collection, as also continuous ingestion of water to maintain constant diuresis. Samples blood and urine taken during the procedure made it possible to simultaneously determine the concentrations of inulin, creatinine and technetium for their subsequent comparison. In this study a significant correlation was found between inulin clearance and technetium and creatinine clearance; the concordance analysis made it possible to determine the significant variability of technetium clearance, with a dispersion of data that in the subgroup of healthy patients donors was even greater.
Furthermore, the concordance analysis comparing creatinine clearance with inulin clearance showed a significant range of variation, which was also greater in the group of healthy patients. It is important to highlight that the concordance analysis used in our study, the one proposed by Bland and Altman, has been used ever more frequently in studies that compare two different methods for measuring clinical values, and has been especially used when the gold standard is to be replaced by another equally reliable but easier method.
Furthermore, correlation analysis only indicates the relationship between two variables, but not their concordance, since data that have a good correlation may have poor concordance, as was clearly shown in this study. Although it is difficult to find different methods with exact concordance, it is necessary to know whether a new method varies in relation to the reference method, and once this is established, its clinical application can be assessed to determine if it can replace the old method.
Irrespective of the method analysed, the limits of concordance were not sufficiently narrow to decide that one of the renal function tests studied could be used as a reference method. This has greater importance in the context of clinical studies, when assessing a potential therapeutic strategy to try and slow down progression of renal damage. The equations can be used to provide approximate values of renal function; however, a method with less variability is necessary.
Our results suggest that technetium clearance could be such method. Due to the limitations mentioned above, we have proposed a panel of GFR markers, to make it easier to detect reduction of renal function at different stages and in different populations; however, this requires further study in the near future. The different renal tests assessed estimated and measured showed an adequate correlation with the reference method; however, they all revealed a considerable lack of concordance, especially the two equations studied, which was more evident in the healthy population.
Technetium clearance showed less discrepancy, in comparison with inulin clearance, although none of the tests analysed is capable of substituting this test. Figure 1. Concordance between inulin clearance and Tc clearance. Figure 2. Concordance between inulin clearance and creatinine clearance. Figure 3. Concordance between inulin clearance and the Cockroft formula. Figure 4. Concordance between inulin clearance and the Levey formula.
Table 1. Home Articles in press Archive. ISSN: Previous article Next article. May Pages More article options. DOI: Comparison of four methods for measuring glomerular filtration rate by inulin clearance in healthy individuals and patients with renal failure. Download PDF. Ignacio Ch?? This item has received. Article information. Show more Show less. The measurement of glomerular filtration rate determined via different methods shows a wide range of variation when compared with inulin clearance, which should be considered in daily clinical practice during the evaluation of renal function.
Tc99m-DTPA clearance.
0コメント