Creatinine clearance and gfr relationship help

creatinine clearance and gfr relationship help

5) What is the difference between creatinine clearance and GFR? . The equation has been programmed into medical decision support software for PDAs and. Creatinine clearance calculator for estimating renal function (glomerular filtration rate) in adults. Equations for Estimating Creatinine Clearance or GFR .. to aid clinicians in estimating renal function for the purposes of drug dosing. The two. Creatinine Clearance Is Not Equal to Glomerular Filtration Rate and Creatinine /blood*; Dose-Response Relationship, Drug; Glomerular.

Serum creatinine production is approximated based on lean body weight because muscle tissue not fat is responsible for creatine production.

creatinine clearance and gfr relationship help

Furthermore, a change in total body mass does not increase the size of the kidney or GFR proportionally. Equations that do not correct or adjust for obesity risk overestimation of true renal function.

Creatinine Clearance Calculator -

In one of the largest study on the topic to date of nearly overweight and obese patients, the following conclusions can be drawn: In the process of conversion, however, the non-normalized value will also overestimate GFR in obese patients.

This equation was not scientifically derived or validated, 15 but is extensively used in medicine. A newer equation, called LBW 19 may be a more promising estimation of lean body weight and has been derived and validated with actual patient data.

Intuitively, this practice does not make sense because rounding a serum creatinine of 0. The literature does not support this practice as it often results in an underestimation of true renal function.

creatinine clearance and gfr relationship help

Rounding Creatinine in Underweight Patients In underweight patients, a low serum creatinine may be more reflective of a decrease in production rather than an increased rate of renal elimination. Similarly to elderly patientsclinicians may be tempted to round creatinine in underweight patients to account for less muscle mass; however, this practice is not supported by the literature.

This correction factor was shown to be more precise and less bias than rounding or making no adjustment. Medications that Modify Serum Creatinine Because serum creatinine undergoes tubular secretion, any medications that interfere with this process will falsely elevate the patient's serum creatinine; however, this will not impact the patient's true GFR.

Creatinine Clearance Calculator

Direct determination of the GFR involves measurement of the renal clearance of inulin a polysaccharide or a radioactive compound. With some limitations, the renal clearance of creatinine creatinine clearance closely matches the GFR.

Therefore the most widely used estimate has been the Cockcroft-Gault equation Table 1 which computes an estimate of creatinine clearance from serum creatinine, age, gender and body weight. As creatinine is derived from muscle it is more accurate to use Lean Body Weight but for practical purposes the actual body weight can be used except in significant obesity.

creatinine clearance and gfr relationship help

Creatinine clearance is a surrogate marker of the GFR but several variables can affect the accuracy of the estimate. In severe renal impairment creatinine is actively secreted and the Cockcroft-Gault equation may over-estimate renal function. As creatinine originates from skeletal muscle its production can be influenced by muscle mass and the degree of physical activity.

It is less accurate in those over 85 years and in people with a body mass significantly outside the normal range. It is not applicable in children.

GFR 1 - Control of GFR

Most laboratories in New Zealand now automatically report eGFR whenever a serum creatinine is requested. This allows the practitioner to assess kidney function without having to estimate creatinine clearance using the Cockcroft-Gault equation.

creatinine clearance and gfr relationship help

Provision of the eGFR allows an initial screen for chronic kidney disease and the possibility of early detection. Ethnicity factors have not yet been calculated for other ethnic groups. This gives a convenient method of consistent reporting of eGFR which can be related to renal function and stages of CKD. An online and downloadable eGFR calculator is available from http:

creatinine clearance and gfr relationship help