The relation between serum MDA and cystatin C levels in chronic spinal cord injury patients.

Objective: The assessment of renal function is particularly important in patients with spinal cord injury (SCI). Creatinine (Cr) is known to be unsuitable as a marker of renal function in SCI because of muscle wasting. Although cystatin C (cys-C) is more reliable than Cr, its expression may be affected by oxidative stress accompanying SCI. The aim of the study was to estimate the cys-C levels in SCI patients with normal functioning kidneys. The prooxidant/antioxidant state in plasma of the patients and controls was measured, and any correlations between these parameters and cys-C were determined.

Methods: Blood samples from 41 chronic SCI patients and 13 controls were obtained. Serum Cr was assayed by the Cobas Integra 400 autoanalyzer and cys-C by particle-enhanced immunoturbidimetry. Heparinized plasma was used for biochemical determinations of vitamin E, total antioxidant status (TAS) and malondialdehyde (MDA).

Results: Cr, TAS and MDA levels were significantly lower in SCI patients compared to the controls (P = 0.007, P = 0.019, P = 0.000, respectively), whereas no difference was seen in cys-C and vit E concentrations. Body mass indices (BMI) of SCI patients were less than those of the controls (P = 0.03). No correlation existed between cys-C and MDA in SCI patients and controls. Cys-C levels were independent from the body mass indices of subjects.

Conclusions: In our study, although BMI and MDA were both affected in SCI patients, cys-C levels were unchanged. Therefore, the measurement of cys-C appeared to be of value for the follow-up of renal function in SCI. The low MDA levels observed in these patients suggest that various adaptation mechanisms may be relevant for subjects undergoing prolonged stress situations.