Measured versus Estimated Creatinine Clearance in the Elderly as an Index of Renal Function

Abstract

Measured endogenous creatinine clearance (requiring 24-hour urine collection) was compared to estimated (calculated) creatinine clearance obtained by 2 formulas and a nomogram (without urine collection), in 26 elderly nursing home residents. All were clinically stable and had adequate intakes of food and fluid. Of the 26 subjects, 23 had a "normal" value for serum creatinine concentration (0.7-1.5 mg/dl) with a mean of 1.1 mg/dl. Measured creatinine clearance (Cer) was reduced in all patients despite a "normal" serum creatinine level. The mean Cer was 47.2 ml/min, with values as low as 21.6 ml/min. Measured Cer findings compared well with estimated (calculated) findings, the correlation coefficients being highly significant in all instances. If it is difficult or impossible to collect a 24-hour urine specimen, a fairly accurate assessment of renal function may be obtained by using a simple formula (or nomogram) for estimating creatinine clearance on the basis of the patient's age, weight (height) and serum creatinine level.

Prediction of creatinine clearance from serum creatinine in spinal cord injury patients

“…weight in kilograms) for prediction of Ccr in females. While Gral and Young (Gral and Young, 1980) did not find this correction to be necessary in their series our data supports the need for such adjustment as suggested by Cockcroft and Gault (Cockcroft and Gault, 1976). Due to severe muscle atrophy the ratio of muscle mass to total body weight in spinal cord injured patients is much less than that of the ambulatory individuals.…”

Effect of intensive glycemic control on microalbuminuria in type 2 diabetes. Veterans Affairs Cooperative Study on Glycemic Control and Complications in Type 2 Diabetes Feasibility Trial Investigators.

“…The reason for the greater deterioration in creatinine clearance in the microalbuminuria subgroup compared with the nonmicroalbuminuria subgroup, regardless of intensity of glycemic treatment, is not clear. The method we used to calculate creatinine clearance compares reasonably with that which uses urinary creatinine concentration as a measure of the glomerular filtration rate (26). Although creatinine clearance may be reduced in extreme aging (26), the degree of deterioration in our patients with Ͼ7 years of type 2 diabetes is greater than that which would be seen as a result of aging during a 2-year period (15,27) or to differences in ACE inhibitor usage.…”

Aging and the Kidneys

“…While muscle mass is 19% of body weight at the age of 25, this rate regresses to about 12% at the age of 70 (12). Therefore, this should be taken into consideration when adjusting medication especially in elderly patients, and it should be kept in mind that there may be a significant decrease in GFR without an increase in serum creatinine concentration (13). In 1999, the Modification of Diet Renal Disease (MDRD) formula was started to be used for GFR calculation.…”