Comparison of Nomogram- and Ultrasound-Determined Renal Depths for Calculation of Glomerular Filtration Rates in Spinal Cord Injury Patients

Abstract

In an informal survey, poor correlation was found between 24-hour creatinine levels and glomerular filtration rates calculated from nuclear medicine studies in spinal cord injury patients. It was speculated that the discrepancies were because the nomograms used in the calculations did not take into account differences in body fat distribution for this patient group. Twenty-five chronic spinal cord injury patients were prospectively studied to compare glomerular filtration rates (GFR) using the nomograms based on height and weight and those using renal depth determined by ultrasound. It was found that the renal depth determined by nuclear medicine was significantly less than that determined sonographically. The mean difference between the total nuclear medicine-based GFR and total ultrasound-based GFR was 17.576 ml +/- 15.449 ml (P < or = 0.001). It was found that there was a significant difference between calculated GFRs based on renal depths as determined by the different methods. In addition, calculated GFRs based on ultrasound-determined depths corresponded more closely to 24-hour creatine clearance levels and with a smaller degree of error than those using renal depths determined by the nuclear medicine nomograms.