Poor correlation between body surface area and glomerular filtration rate

Purpose: The aim of this study was to determine the correlation between body surface area (BSA) and glomerular filtration rate (GFR) measured by Tc-99m DTPA clearance in adult patients with cancer. Methods: GFR was determined by Tc-99m DTPA clearance in adult patients with cancer. Height and actual body weight were measured, ideal body weight was calculated. BSA was calculated using the Du Bois and Du Bois linear method using both actual and ideal body weight. Results: Included in the study were 122 patients. The mean GFR measured by Tc-99m DTPA clearance was 87 ml/min (range 30 174 ml/min). The mean BSA (actual weight) was 1.76 m(2) (median 1.73 m(2), range 1.31-2.58 m(2)). The mean BSA (ideal body weight) was 1.63 m2 (median 1.63 m(2), range 1.20 2.00 m(2)). The overall correlation between BSA (actual weight) and GFR in this adult population was r = 0.24, and the 95% confidence interval was 0.06-0.4. The correlation between BSA (ideal body weight) and GFR was r = 0.22. The correlation between BSA and GFR excluding patients with a BSA <1.5 m(2) or >2.0 m(2) was 0.12, When patients with GFR <50 ml/min or >100 ml/min were excluded, the correlation with BSA was 0.07. The correlations between GFR and height, actual weight and ideal weight were 0.22, 0.21 and 0.22, respectively. Conclusions: This study demonstrated a poor correlation between GFR determined by Tc-99m DTPA clearance and BSA calculated using the Du Bois and Du Bois linear method. The 95% confidence interval for the correlation between BSA and GFR was 0.06 0.4 indicating that a strong applicable clinical correlation is very unlikely.