CRCL Calculator

How does this CRCL calculator work?

This is a health tool that aims to calculate the creatinine clearance through the Jelliffe equation that requires serum creatinine as provided through a blood test, age, gender, height and weight. The data input is very straight forward and you can also choose whether you want to use the English or Metric system.  

The CRCL Calculator will display your creatinine clearance level in ml/min and your body surface area (BSA) that can be calculated by 5 different formulas (you can select the one you prefer), BMI, ideal body weight and lean body mass. The tool can be used for adults only and please note that the serum creatinine levels should be stable:

■ Estimated creatinine clearance rate (eCCr):

eCCr = {[98 – 0.8 * (Age – 20)] * [1 – (0.1 * Gender)] * (BSA/1.73)}/(Serum creatinine in µmol/L * 0.0113)

Where:

Gender: is 0 in case of male and 1 in case of female.

■ BSA: body surface area calculated by the desired method (you can choose from Boyd’s formula, DuBois’s formula, Gehan & George’s  formula, Haycock’s formula or Mosteller’s formula).

Serum creaninine in µmol/L. In case the serum creatinin is expressed in mg/dL, the conversion from mg/dL to µmol/L should be made by the following rate: 1 mg/dL = 88.4 µmol/L.

Source: adapted from Oxford Journals.

■ Estimating body surface area by Boyd’s method:

BSA = 0.0003207 x (Height in cm)^0.3 x (Weight in grams)^{(0.7285 - ( 0.0188 x Log(Weight))}

■ Calculating body surface area by DuBois’s formula:

BSA = 0.007184 x (Height in cm)^0.725 x (Weight in kg)^0.425

■ Computing body surface area by Gehan & George’s equation:

BSA = 0.0235 x (Height in cm)^0.42246 x (Weight in kg)^0.51456

■ Finding the body surface area by Haycock’s formula:

BSA = 0.024265 x (Height in cm)^0.3964 x (Weight in kg)^0.5378

■ Estimating body surface area by Mosteller’s equation:

BSA = Square root of (((Height in cm) x (Weight in kg))/ 3600)

Example calculation

Let’s take the case of a 58 year old male, weighing 224 lbs at a height of 6ft 4in and with a value of serum creatinine of 1.6 mg/dl. The result is:

■ The estimated creatinine clearance rate (eCCr): 57.066 ml/min;

■ Body Surface Area (BSA): 25.125 Square Feet or 2.334 m²;

■ BMI: 27.266;

■ Body status based on WHO BMI range: Overweight;

■ Ideal body weight is between 151.98 lbs and 205.38 lbs;

■ Lean body mass: 168.22 lbs.

What is serum creatinine?

This is a value expressed either in mg/dL or in µmol that represents the component found in muscles that is then cleared through kidneys resulting the creatinine clearance which is the main analysis of the kidney’s filtering function.

The normal values are between 0.7 and 1.3 mg/dl for men and 0.6 and 1.1 mg/dl for women as the last have usually lower levels because they have less muscle mass than men.

This would also mean that muscular men have higher levels of it as well and this should be taken in consideration while calculation the clearance in order to avoid a false result. If kidneys don’t filter creatinine properly its blood levels increase. Serum creatinine levels are used to retrieve the creatinine clearance or GFR value.

Which are the normal levels of creatinine clearance?

Creatinine Clearance is usually measured in milliliters/ minute (ml/min) and normal values are around 98-136 ml/min for males and 88-128 ml/min for females.

In general healthy adults have levels ranging 80-130 ml/min. Higher levels are sign for a variety of kidney disfunctions, infections, reduced blood flow, dehydration or muscular problems.

References

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

2) Gault MH, Longerich LL, Harnett JD, Wesolowski C. (1992) Predicting glomerular function from adjusted serum creatinine. Nephron; 62 (3): 249–56.