Platelet distribution width as a marker for predicting lupus nephritis

Background: Lupus nephritis (LN) is an important manifestation of systemic lupus erythematosus (SLE). The aim of this study was to investigate the predictive value of platelet distribution width (PDW) in LN. Methods: A retrospective study involving 212 SLE patients and 201 healthy controls were performed. All clinical characteristics and laboratory data were collected from their medical records. Results: The level of PDW was significantly decreased in SLE patients, which was negatively correlated with SLE disease activity index 2000 (SLEDAI-2K) score, disease duration, and 24-hour (24-h) urine protein, while positively correlated with serum IgG and IgM. There were more LN patients in low-PDW group than normal-PDW and high-PDW groups. In low-PDW group, SLEDAI-2K score, 24-h urine protein level, and anti-dsDNA antibody level was significantly higher, while serum IgG level was markedly lower. Moreover, PDW was negatively correlated with 24-h urine protein and disease duration, and it was positively correlated with serum IgG in LN patients. In addition, the area under the ROC curve of PDW was 0.87 and the optimal clinical cutoff level was 12.9, which provided a 87.41% sensitivity and a 74.63% specificity. Decreased PDW combined with high 24-h urine protein exhibited an excellent diagnostic value for LN. Importantly, 16.67% LN patients with negative 24-h urine protein can be detected in low PDW group. Conclusion: PDW may be a potential marker for predicting LN. Low PDW accompanied with high 24-h urine protein may be a useful indicator for diagnosing LN.