Serum Creatinine as Marker of Kidney Function in South Asians

Abstract

Migrant populations of South Asian origin have a higher risk for chronic kidney disease than the native whites. Several formulas have been developed to estimate kidney function from serum creatinine concentration. However, none of these has been validated in the South Asian population, which generally has different muscle mass composition than whites. A population-based cross-sectional study was performed on 262 individuals who were aged >40 yr in Karachi, Pakistan. Reduced GFR was defined as creatinine clearance (Ccr) measured in 24-h urine collection of <60 ml/min per 1.73 m 2 . Creatinine excretion was compared with age-and gender-matched white individuals by comparison of observed versus expected results on the basis of a formula using t test. The agreement among Cockcroft Gault (CG) Ccr and Modification of Diet in Renal Disease (MDRD) Study GFR equations was assessed by regression analyses, and the degree of accuracy of estimated versus measured GFR was determined. Mean (95% confidence interval) creatinine excretion was 1.7 (1.0 to 2.4) mg/kg per d lower than expected for age-and gender-matched white individuals (P < 0.001). The coefficient of determination for measured Ccr on the logarithmic scale was 66.7 and 55.6% for the CG and MDRD Study equations, respectively. The proportion of estimates within 20, 30, and 50% of measured Ccr values was 47.7 versus 32.8% (P < 0.001), 64.9 versus 49.6% (P < 0.001), and 79.4 versus 72.9 (P ‫؍‬ 0.07) for CG versus MDRD Study equations, respectively. Lower mean creatinine excretion in these individuals may explain, in part, suboptimal agreement between estimated versus measured GFR. Inclusion of terms for ethnic and racial groups other than white and black might improve the performance of GFR estimating equations.

Doctors’ knowledge and practices regarding chronic kidney disease at a tertiary care hospital

“…However, a study on general practitioners (GPs) in Karachi showed that 78% of them would rely on serum creatinine for detection of kidney disease [38]. Evidence has shown that eGFR measurement in Pakistan by the MDRD equation or calculating the creatinine clearance using the Cockcroft Gault equation is a better predictor of reduced GFR than serum creatinine alone [43], and using serum creatinine alone may result in significant under-recognition of CKD as the level may still be within normal range even when the kidney function is impaired significantly.…”

Assessment of Racial Disparities in Chronic Kidney Disease Stage 3 and 4 Care in the Department of Defense Health System

“…Furthermore, we did not have information on height or weight to calculate patient body surface area or ideal body weight. There are known reported limitations of the widely used MDRD equation, particularly for Asians (17), which are only partly explained by differences in body size. Because our information on this category is by definition quite limited, our conclusions must also be quite limited.…”

Monitoring renal function: measured and estimated glomerular filtration rates - a review

“…Therefore, clearance measurements are still required for groups who were underrepresented in the original MDRD sample in order to fully validate the formula for all patients. These include: patients at extremes of age and body size; severely malnourished or obese patients; patients with skeletal muscle diseases, paraplegia, or quadriplegia, vegetarians, and those with rapidly changing kidney function as in acute kidney injury (19,22). The MDRD and C-G equations are inappropriate to estimate GFR in healthy individuals and have been shown to clearly underestimate GFR above approximately 60 mL·min -1 ·1.73 (m 2 ) -1 and to markedly overestimate GFR below approximately 20 mL·min -1 ·1.73 (m 2 ) -1 and in nephrotic range proteinuria (23)(24)(25).…”