Prediction serum creatinine

The effect of hemofiltration on drug elimination can be estimated from serum creatinine (SCr), age, and the MDRD-2 formula to predict the combined effect of filtration rate (eGFR = GFRresidual + HFR) on drug clearance and drug half-life during hemofiltration. 

Levey AS, Bosch JP, Lewis JB, et al. A more accurate method to estimate glomerular filtration rate from serum creatinine A new prediction equation. Modification of Diet in Renal Disease Study Group. Ann Intern Med 1999 130 461 470. 

Thus, kanamycin half-lives (h) can be predicted in patients with varying degrees of (stable) renal failure by multiplying the serum creatinine level (in mg/lOOmL) by 3. 

It is well known that both glomerular and tubular renal functions decline with age in at least one third of individuals. As a result there is greater variation in renal function in older subjects. Glomerular filtration rate can be predicted by creatinine clearance, which can be estimated based on measured serum creatinine (Sercr) concentration. One such formula is the Cochrane and Gault formula in which... 

Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron 1976 16(1) 31-41. 

Drugs cleared by the renal route often require adjustment of clearance in proportion to renal function. This can be conveniently estimated from the creatinine clearance, calculated from a single serum creatinine measurement and the predicted creatinine production rate. 

The GFR can be measured most precisely using the 51Cr-EDTA clearance method, but for everyday practice the determination based on nomograms using serum creatinine values provides an adequately accurate estimate. It should be emphasized, however, that the myelotoxicity is also influenced by the general condition of the patient, especially by the extent of bone marrow reserve. Therefore, even when using an AUC-based administration scheme the seriousness of myelotoxicity cannot be accurately predicted. 

Braun JP, Perxachs A, Pechereau D, de la Farge F (2002) Plasma cystatin C in the dog reference values and variations with renal failure. Comp Clin Pathol 11 44 19 Cockcroft DW, Gault MH (1976) Prediction of creatinine clearance from serum creatinine. Nephron 16 31-41 Corman B, Michel JB(1987) Glomerular filtration, renal blood flow, and solute excretion in conscious aging rats. Am J Physiol 22 R555-R560... 

When 60 patients (22 men, 38 women) who had taken lithium for 1 year or more (mean 6.9 years mean serum concentration 0.74 mmol/1) were interviewed about adverse effects, 60% complained of polyuria-polydipsia syndrome (serum creatinine concentrations were normal) and 27% had hypothyroidism requiring treatment (108). Weight gain was more common in women (47 versus 18%) as were hypothyroidism (37 versus 9%) and skin problems (16 versus 9%), while tremor was more common in men (54 versus 26%). Weight gain of over 5 kg in the first year of treatment was the only independent variable predictive of hypothyroidism. 

It is difficult to obtain an accurate measure of renal function in patients with cirrhosis. A number of studies have shown that they tend to have low serum creatinine levels. This has been explained by a reduced muscle mass in cirrhotic patients and a reduced conversion of creatine to creatinine [10]. The calculation of creatinine clearance using the Cockcroft and Gault formula is also inaccurate in predicting GFR in these patients because it uses the serum creatinine level (which may be falsely low) and body weight in the calculation, which is likely to be inflated due to the presence of ascites [12]. The measured creatinine clearance, based on urinary excretion of creatinine, should theoretically be more accurate, even in patients with reduced muscle mass or impaired creatinine synthesis. However, it has been shown that this also overestimates the GFR because of an increased fractional tubular secretion of creatinine in cirrhotic patients, particularly those with reduced GFR [10]. 

There is growing popularity of the formulae used to predict eGFR. While Cockcroft/Gault is the oldest, the MDRD formulae has gained greater use since it is most useful at GFR < 60 ml/min/1.73m [111]. How reliable these values are with rapidly changing serum creatinine values is problematic. 

Bachorzewska-Gajewska FI, Malyszko J, Sitniewska E, Malyszko JS, Pawlak K, Mysliwiec M, Lawnicki S, Szmitkowski M, Dobrzycki S. Could neutrophil-gelatinase-associated lipocalin and cystatin C predict the development of contrast-induced nephropathy after percutaneous coronary interventions in patients with stable angina and normal serum creatinine values Kidney Blood Press Res 2007 30 408-415. 

Bostom AG, Kronenberg F, Ritz E. Predictive performance of renal function equations for patients with chronic kidney disease and normal serum creatinine levels. J Am Soc Nephrol 2002 13 2140-4. 

Levey AS, Greene T, Kusek JW. A simplified equation to predict glomerular filtration rate from serum creatinine. J Am Soc Nephrol 2000 11 A0828. 

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