Monitoring serum beta-2 microglobulin is a noninvasive approach for predicting lupus nephritis, clinical disease activity, and cumulative damage in patients with systemic lupus erythematosus (SLE), according to investigators.
Among 100 patients with SLE, 60 tested positive and 40 tested negative for serum beta-2 microglobulin, a protein secreted by immune cells. Compared with the negative group, the positive group had significantly higher levels of 24-hour urinary protein excretion, active urinary sediment, albuminuria, serum creatinine, blood urea nitrogen (BUN), erythrocyte sedimentation rate, and C-reactive protein along with lower estimated glomerular filtration rate (eGFR), consumed C3 and C4, and hemoglobin, Mohammed Abd El Monem Teama, MD, of Ain Shams University in Cairo, Egypt, and colleagues reported in Rheumatology International. The positive group was significantly more likely to have higher scores on both SLEDAI-2 K and the SLICC/ACR Damage Index scores. Results show the positive group had greater prevalence of nephritis, oral ulcer, serositis, and neurological, cardiac, and pulmonary damage.
According to receiver operating curve analyses, the best cutoff value of serum beta-2 microglobulin for predicting lupus nephritis was more than 2.6 µg/mL (specificity 74.47%, positive predictive value [PPV] 80.3%, sensitivity 92.45%, negative predictive value [NPV] 89.7%), with an area under the curve of 0.874.
For predicting SLE disease activity, the best cutoff value of serum beta-2 microglobulin was more than 2.2 µg/mL (specificity 85%, PPV 90.6%, sensitivity 96.67%, NPV 94.4%) with an area under the curve of 0.961.
For predicting cumulative damage, the best cutoff value of serum beta-2 microglobulin was more than 2.6 µg/mL (specificity 65.45%, PPV 68.9%, sensitivity 93.33%, NPV 92.3%), with an area under the curve of 0.836.
“Serum [serum beta-2 microglobulin] levels may be utilized for anticipating [lupus nephritis] progression as well as identifying disease severity and cumulative damage for proper management with significant sensitivity and specificity,” Dr El Monem Teama’s team concluded.
Mohamed Gamal D, Mohammed Badr F, Ibrahim Abd El Fattah Taha S, Moustafa NM, Abd El Monem Teama M. Serum beta‑2 microglobulin as a predictor of nephritis, disease activity, and damage score in systemic lupus erythematosus: a cross‑sectional study. Rheumatol Int. 2023 Feb;43(2):323-333. doi:10.1007/s00296-022-05221-1