Creatinine Clearance Calculators:

While these calculators were created under Excel 95 and 97 back in 1999, the calculations that they rely on are still current as of this update.  These excel sheets are basic calculators which allow for real-time manipulation of height, weight, and serum creatinine and allow observation of the effect on creatinine clearance.  Please note that only the Excel 95 version was updated fully and was checked for accuracy.  The Excel 97 version was barely tested and did not take into account adjusted body weight calculations.  

You can download the excel sheets here:  

Creatinine Clearance Calculator for Excel97
Creatinine Clearance Calculator for Excel95
Creatinine Clearance Calculator in use at Newport Hospital (Excel95)

This information should be used for education or to complement clinical knowledge only.  What is creatinine clearance?  

Summary:

The calculation of creatinine clearance is an indicator of glomerular filtration rate (GFR) and is used clinically as an indicator of overall renal function.  Several dosing regimes are altered in renal impairment.  

What does the calculator do?
The excel calculator (95 version) is able to take the values of sex, age, height (cm), weight, and plasma creatinine and by use of the Cockroft and Gault equation calculates the creatinine clearance. The calculator will also calculate and use the most appropriate figure for weight depending on the patient's proximity to their ideal weight.

What determines the weight used?
Ideal body weight is calculated based upon sex and height. The calculator uses actual body weight when the patient is below their ideal weight. It uses ideal body weight if they are above their body weight by less than 20%. If they are 20% or more above their ideal weight the adjusted body weight will be used.

What is Creatinine?
Creatinine is a byproduct of creatinine metabolism that occurs in the muscle. This is why plasma creatinine is dependent upon muscle mass. Creatinine is one of the indicators of renal function. Other, more precise measurements are used in research such as inulin clearance, but for clinical purposes creatinine measurements are the standard. 

What does Creatinine clearance mean?
A creatinine clearance of 50 or less indicates renal insufficiency. The lower the creatinine clearance, the more trouble the kidneys are having eliminating substances.

How do I use the creatinine clearance values?
Many textbooks, such as "Drug Prescribing in Renal Failure" ed. Bennett, and many others will make recommendations based upon the medications the patient is on and the degree of renal insufficiency. Recommendations may be to lower the frequency of doses, lower strengths given, or a combine both strategies. 

What medications should get me thinking about renal function?
Medications which cause toxicity or have a narrow therapeutic index should be mentally flagged, as well as those that are heavily renally excreted. Digoxin, Glyburide, Allopurinol, Fluroquinolones and Aminoglycosides are examples of medications which often require adjustment. Specific guidelines should be consulted for each medication.