High disease activity correlate with decreased serum calcium in systemic lupus erythematosus

We evaluated the clinical and laboratory features of decreased serum calcium (albumin corrected or uncorrected) compared to non-hypocalcemia in SLE patients. Exploring the value of serum calcium in assessing the activity and prognosis of SLE disease. Retrospective analysis and comparison of clinical and laboratory data obtained during the treatment period of SLE patients from 2018 to 2023. Both quantity and titer of serum anti-dsDNA antibodiesin SLE patients with hypocalcemia were significantly increased, and peripheral leucocytes, platelets, complement C3 or C4 reduced, while urinary cast and 24 h urine protein elevated. SLEDAI-2 K, BILAG and PGA have confirmed that SLE patients with decreased serum calcium had stronger disease activity, even without positive titers of anti-dsDNA antibodies. Multivariate analysis showed that the decreased serum calcium (OR, 0.31; 95% CI, 0.11, 0.89; P, 0.030) and positive anti-dsDNA antibodies (OR, 0.13; 95% CI, 0.04, 0.44; P, 0.001) are risk factors for increased disease activity in SLE. The Cox model showed that for newly diagnosed SLE and hypocalcemia patients, the stability time of GCs treatment may be prolonged. With the recovery of total calcium, disease activity and laboratory indicators could improve.SLE patients with decreased serum calcium have stronger disease activity and require longer treatment time for remission. Serum calcium levels may assist in assessing disease activity and predicting prognosis.