Serum total cholesterol, calcium, and IgG as discriminatory markers of lupus nephritis in children with systemic lupus erythematosus.

OBJECTIVE: Childhood-onset systemic lupus erythematosus (cSLE) commonly involves lupus nephritis (LN), a severe complication. Reliable serological discriminatory markers for LN are lacking. This study aimed to identify routine laboratory parameters associated with prevalent LN in cSLE. METHODS: A total of 187 children with diagnosed SLE were divided into LN group (n = 84) and non-LN groups (n = 103) based on renal biopsy findings. Clinical and laboratory data were compared. Multivariate logistic regression identified independent associated factors for LN. Furthermore, the correlations between these laboratory parameters and renal function indicators were analyzed. Receiver operating characteristic (ROC) curves were plotted to evaluate the discriminatory performance of these indicators for LN. RESULTS: Compared to the non-LN group, the LN group showed significant alterations in multiple serum parameters (e.g., lipids, coagulation markers, immunoglobulins, complement). Multivariate logistic regression analysis identified decreased serum total calcium (Ca) and IgG, and elevated serum total cholesterol (TC) as independent associated factors for LN (all P < 0.05). Serum TC correlated positively, and serum total calcium correlated negatively, with serum creatinine and 24-hour urine protein (all P < 0.05). The areas under the ROC curve (AUC) for discriminating the presence of LN using serum TC, Ca, and IgG alone were 0.762, 0.697, and 0.684, respectively. Their combination achieved the highest AUC of 0.852 (95% CI: 0.796∼0.908). CONCLUSION: A multivariate logistic regression model incorporating serum TC, Ca, and IgG levels demonstrates strong discriminatory utility for prevalent LN in children with SLE.