Cistatina C: Um Marcador de Função Renal Promissor em Doentes com Lúpus Eritematoso Sistémico?
<strong>Purpose:</strong> Cystatin C has a higher correlation with glomerular filtration rate and a more significant clinical prognosis than creatinine. We sought to determine whether it is a marker of renal function different from creatinine (cystatin C potentially superior to creatinine), in patients with systemic lupus erythematosus.<br /><strong>Material and Methods:</strong> 37 patients with systemic lupus erythematosus were evaluated. Serum cystatin C was determined by nephelometry and creatinine by modified Jaffe method. We compared five formulas: Chronic Kidney Disease – Epidemiology Collaboration cystiatin; Chronic Kidney Disease – Epidemiology Collaboration creatinine-cystatin; Cockcroft-Gault; Modification of Diet in Renal Disease and Chronic Kidney Disease – Epidemiology Collaboration creatinine, using the latter as a reference. We analyzed the influence of clinical and laboratory factors in cystatin C variation, using multivariate linear regression.<br /><strong>Results:</strong> Cystatin C was singly elevated in ten participants, versus none isolated creatinine elevation, and this difference was significant (p = 0.002). There was a difference between the estimated glomerular filtration rate by Chronic Kidney Disease – Epidemiology Collaboration cystatin and by Chronic Kidney Disease – Epidemiology Collaboration creatinine (-6.0541 mL/min/1.73 m2, p = 0.07), more pronounced for lower glomerular filtration rate. Consequently, Chronic Kidney Disease – Epidemiology Collaboration cystatin reclassified 4 patients as having chronic kidney disease de novo and 1 patient as not having chronic kidney disease (p = 0.375).<br />Cystatin C was only significantly influenced by age (p < 0.001).<br /><strong>Discussion:</strong> Several reports showed cystatin C as a better marker to define chronic kidney disease, allowing more accurate classification and risk stratification, compared with creatinine. In this study, Cystatin C revealed as a promisor marker of renal function in patient with lupus, mainly in patients with lower glomerular filtration rates. The correlation between age and cystatin C seems to be a confounding<br />factor, as glomerular filtration rate physiologically declines with ageing.<br /><strong>Conclusion:</strong> Cystatin C was potentially superior to creatinine and in this study and cystatin C seems to detect changes in glomerular filtration rate earlier than creatinine and may be a better screening method for chronic kidney disease in systemic lupus erythematosus.