Creatinine Clearance - Multi-calc Advanced Version - co*ckcroft And Gault Crcl (2024)

Multiple Creatinine Clearance Methods and CKD Staging

Patient Name: Location:

Age:Scr: Gender:
Is the serum creatinine (Scr) currently stable:

Height: Weight:

For MDRD and CKD-EPI equation. specify race:

Select serum creatinine reference standard: [more info]

Staging

Chronic kidney disease: "defined as kidney damage or GFR < 60 ml/min/1.73m² for ≥3 months.Kidney damage is defined as pathologic abnormalities or markers of damage,including abnormalities in blood or urine tests or imaging studies." ⁹

Restrictions

Restrict the maximum calculated clearance to this value:

Select option for calculating the IBW for patients under 60 inches(default option - BMI method):

[See reference section]

Creatinine Clearance methods

co*ckcroft and Gault equation utilizing the tbw (Total body weight) tocalculate an estimated CrCL - co*ckcroft and Gault equation:

CrCl = [(140- age) x TBW] / (Scr x 72) (x 0.85 for females)

co*ckcroft andGault equation utilizing the ibw (Ideal body weight) to calculate anestimated creatinine clearance
co*ckcroft and Gault equation:

CrCl =[(140 - age) x IBW] / (Scr x 72) (x 0.85 for females)

Note: if theABW (actual body weight) is less than the IBW use the actual body weight forcalculating the CRCL.

Estimate Ideal body weight in (kg)
Males:IBW = 50 kg + 2.3 kg for each inch over 5 feet.
Females: IBW = 45.5 kg +2.3 kg for each inch over 5 feet.

co*ckcroft and Gault equation utilizing the adjusted body weight tocalculate an estimated creatinine clearance

Note: (Multiply result by 0.85 for females)
AjBW = adjusted body weight:
AjBW = IBW + 0.4( ABW - IBW)

Estimated IBW:
Males: IBW = 50 kg +2.3 kg for each inch over 5 feet.
Females: IBW = 45.5 kg + 2.3 kg foreach inch over 5 feet.

Some studies have shown that utilizing theadjusted body weight improves accuracy compared to other commonly usedequations in estimating the creatinine clearance in the elderly population.

Simplified 4-variable MDRD study formula:

Key point: Early statistical analysis shows very promising results. Mayrepresent the most accurate choice of this group. This may be especiallytrue in chronic kidney disease.

CKD-EPI equation:

GFR = 141 x min(Scr/κ,1)α x max(Scr/κ,1)-1.209 x 0.993Age x 1.018 [if female]
x 1.159 [if black]

References

1. co*ckcroft DW, Gault MH. Prediction of creatinine clearance from serumcreatinine. Nephron 1976;16(1):31-41
2. Davis GA, Chandler MH. Comparison of creatinine clearance estimationmethods in patients with trauma. Am J Health-Syst Pharm 1996;53:1028-32.
3. Dawson-Saunders B, Trapp RG. Basic and Clinical Biostatistics. 2nd ed.Norwalk, CT: Appleton & Lange; 1994.
   
4. Demirovic JA, Pai AB, Pai MP. Estimation ofcreatinine clearance in morbidly obese patients. Am J Health Syst Pharm.2009 Apr 1;66(7):642-8.
   
   "An LBW estimate, based on TBW and BMI,incorporated into the co*ckcroft-Gault equation provided an unbiased,relatively precise, accurate, and clinically practical estimate of24-hour measured CLcr in morbidly obese patients."

   Lean body weight - male:9270 x tbw/6680 + 216 x BMI
   Lean body weight - female:9270 x tbw/8780 + 244 x BMI

   Obese study population: As expected, use of co*ckcroft-Gault_TBWgrossly overestimated measured CL_cr. The co*ckcroft-GaultABW_0.3,co*ckcroft-GaultABW_0.4, and Salazar-Corcoranequations all overestimated measured CL_cr values in the study patients. Incontrast, the co*ckcroft-Gault_IBW and the MDRD4 equationsunderestimated measured CL_cr values. The co*ckcroft-Gault_LBWequation was the most precise, and the MDRD4 equation was the least. Theco*ckcroft-Gault_FFW and co*ckcroft- Gault_LBWequations yielded the highest accuracy (55-61%), in yielding values thatwere within 30% of the measured CL_cr.

5. Dettli LC. Drug dosage in patients with renal disease. Clin PharmacolTher 1974;16:274-80.
   
6. Drusano LG, Munice HL, Hoopes JM et al. Commonly used methods ofestimating creatinine clearance are inadequate for elderly debilitatednursing home patients. J Am Geriatrics Soc 1998;36:437-41.
   
7. Hailemeskel B, Namanny M, Kurz A. Estimating aminoglycoside dosagerequirements in patients with low serum creatinine concentrations. Am JHealth-Syst Pharm 1997;54:986-7.
   
8. Jelliffe RW. Estimation of creatinine clearance when urine cannot becollected. Lancet 1971;1:975-6.
9. KDOQI Clinical Practice Guidelines for Chronic Kidney Disease:Evaluation, Classification, and Stratification. © 2002 National KidneyFoundation. (link)
   
10. Levey AS, Greene T, Kusek JW, et al. A simplified equation to predictglomerular filtration rate from serum creatinine (Abstr) J Am Soc Nephrol2000;(11):155A
    
11. Levey AS, Greene T, Schluchter MD, et al. Glomerular filtration ratemeasurements in clinical trials. Modification of Diet in Renal Disease StudyGroup and the Diabetes Control and Complications Trial Research Group. J AmSoc Nephrol 1993;4(5):1159-71
    
12. Levey AS. Assessing the effectiveness of therapy to prevent theprogression of renal disease. Am J Kidney Dis 1993;22(1):207-14
    
13. Levey AS, Bosch JP, Lewis JB, et al. A more accurate method to estimateglomerular filtration rate from serum creatinine: a new prediction equation.Modification of Diet in Renal Disease Study Group. Ann Intern Med1999;130(6):461-70
14. Levey AS, Stevens LA, Schmid CH, Zhang YL, Castro AF 3rd, Feldman HI,Kusek JW, Eggers P, Van Lente F, Greene T, Coresh J. A NewEquation to Estimate Glomerular Filtration Rate. Ann Intern Med. 2009; 150:604-612.
    
15. Rhodes RS, Sims PJ, Culbertson VL et al. Accuracy of creatinineclearance estimates in geriatric males with elevated serum creatinineclearance. J Geriatric Drug Ther 1991;5:31-45.
    
16. Salazar DE, Corcoran GB: Predicting creatinine clearance and renaldrug clearance in obese patients from estimated fat-free body mass. Am JMed 84: 1053-1060, 1988.
    
17. Smythe M, Hoffman J, Kizy K et al. Estimating creatinine clearance inelderly patients with low serum creatinine concentrations. Am J Hosp Pharm1994;51:189-204.
18. Wilhelm SM, Pramodini KP. EstimatingCreatinine Clearance: A Meta-analysis. Pharmacotherapy 2011 31:7 ,658-664.

    "Conclusion. Using the co*ckcroft-Gault equation with nobody weight (NBW) and actual Scr value most closely estimated measuredClcr. In obese patients, it may be reasonable to use actual body weightwith a correction factor of 0.3 or 0.4 and actual Scr value in theco*ckcroft-Gault equation. Based on this analysis, the use of total bodyweight, ideal body weight, and a rounded Scr value cannot berecommended."

19. Winter MA, Guhr KN, Berg GM. Impact of various body weights andserum creatinine concentrations on the bias and accuracy of theco*ckcroft-Gault equation. Pharmacotherapy 2012; 32: 604-612 [PMID:22576791 DOI: 10.1002/j.1875-9114.2012.01098.x]
    Quotes: [Largest study so far....total of3678 patients]
    Regarding Salazar equation: This equation,however, was not consistently shown in studies to be asuperior predictor of renal function. It is not widely used inclinical practice and has not been validated inpharmaco*kinetic studies. In addition, the Salazar-Corcoranequation is not recognized by the National Kidney Foundation.

    Regarding CG -LBW equation: Our findings donot support those conclusions and are different from a recentinvestigation of Clcr in 54 morbidly obese patients that foundthat adjusting an obese patient's weight to a fat-free weightor lean body weight predicted a Clcr calculated with the C-Gequation without bias. Notably,our study included 2065 obese or morbidly obese patients, farmore than other published studies.

    Conclusions: An unbiased C-G Clcr can becalculated using actual body weight in underweight patientsand ideal body weight in patients of normal weight. UsingABW0.4 for overweight, obese, and morbidly obese patientsappears to be the least biased and most accurate method forcalculating their C-G Clcr. Rounding Scr in patients with lowScr did not improve accuracy or bias of the Clcr calculations.

Background info for height less than 60 inches

1] Intuitive Method:
Reference: Murdaugh LB. Competence Assessment Tools forHealth-System Pharmacies. 5th ed. Bethesda, MD: ASHP; 2015. [Chap:29 Medicationdosing in Patients with Renal Dysfunction]
IBW (Male) = 50kg - 2.3kg for each inch below 60 inches
IBW (Female) = 45.5kg - 2.3kg for each inch below 60 inches
Comments: For patients just a few inches below 60inches, the result is reasonable, however, 2.3 kg/inch is excessive whenused for shorter heights. At 38 inches for a male, and 40 inchesfor a female, the IBW is ZERO. This provides support for thenext method below.

2] Baseline Method:
The baseline method starts with the initial ideal body weight baselinevalues e.g. 60 inch male patient - 50kg and 60 inch female patient -45.5kg. Male patient: 50kg /60 inches = 0.833 kg/inch.Female patient = 45.5kg/60 inches = 0.758 kg/inch. Thereforea male patient - 55 inches: IBW = 50kg - (0.833 x 5) = 45.8kg versus thefirst method = 50kg - (2.3 x 5) = 38.5 kg.
[Reference: reasonable assumption based on the standard ideal body weightequations and the baseline weights established for a height of 60 inches.
Also review: Murphy JE. Introduction. In: Murphy JE, ed. Clinical Pharmaco*kinetics, 5th ed. Bethesda, MD: American Society of Health-System Pharmacists, 2011:xxxiv.- Note: for patients who are less than 60 inches tall, the weight should be decreased more conservatively than 2.3kg/inch.]

3] BMI method:

References:
Wiggins, K. L. (2004). Renal care: Resources and practical applications.Chicago: American Dietetic Association. pg 12.

Barash, P. G., Cullen, B. F., & Stoelting, R. K. (1989). Clinical anesthesia.Philadelphia: Lippincott. chap:47:1231

Remember that BMI = weight(kg)/height² (meters squared).Next, we will establish an 'ideal' BMI based on values in the standardIBW equations: Male: 60 inches - 50kg - BMI= 21.53. Female:60 inches - 45.5kg - BMI= 19.59. We can then use this associationto generate an equivalent ideal weight based on this standardized BMIand the height of the patient. Using the example above (55 inchmale patient):
IBW = 21.53 (BMI value above) x (55 x 0.0254)² =42 kg.
Background info: the body mass index quantifies the amount of tissue mass at aparticular height (units: kg/m²). Example: the followingpatients all have a BMI ~ 21: 130 lbs - 5'6", 163 lbs - 6'2",107 lbs - 5'.

4] Hume method:
LBW (Males) = (0.3281 x Weight in kg) + (0.33939 x Height in cm) -29.5336
LBW (Females) = (0.29569 x Weight in kg) + (0.41813 x Height in cm) -43.2933
Using the example above: (55 inch male patient): IBW=36.9 kg

Reference: Hume R. Prediction of lean body mass from height andweight. J Clin Path(1966), 19, 389.