Monitoring of renal function in patients with spinal cord injury

Objective To assess the sensitivity of serum creatinine level in detecting clinically important and early deterioration of renal function in patients with spinal cord injury (SCI), and to evaluate the optimal method of determ ining creatinine clearance in these patients. Patients and methods The serum creatinine level of 36 patients (25 parapleg ics and 11 quadriplegics) was evaluated and compared with the corresponding measured creatinine clearance rate. Correlations were also assessed betwee n the creatinine clearance measured by 24-h endogenous clearance, single-sh ot Tc-99m-labelled diethylenetriamine pentaacetic acid (Tc-99m-DTpA) cleara nce technique, and the Cockcroft-Gault formula, to test their validity. Results Of the 36 patients 11 (31%) had a measured creatinine clearance of <100 mL/min (mean 84.8) and a corresponding normal serum creatinine level. Creatinine clearance calculated by the Cockcroft-Gault formula did not corr elate well with that measured by the 24-h endogenous clearance (r=0.426) an d Tc-99m-DTPA clearance (r=0.366), overestimating creatinine clearance in a ll but three patients. The mean (sD) difference between the creatinine clea rance measured by the 24-h and DTPA clearance technique was 17.7 (16.5)% an d the correlation between these techniques was good (r=0.71). Conclusion Serum creatinine level is not sensitive in detecting early deter ioration of renal function in patients with SCI. The Cockcroft-Gault formul a generally significantly overestimates the true creatinine clearance and i s not recommended. The 24-h endogenous creatinine clearance measured on app ropriately collected urine samples is an acceptable accurate and practical method of determining glomerular filtration rate in patients with SCI.