Serum lactate dehydrogenase and its isozymes in lupus nephritis

The relationship between the renal pathologic activity of systemic lupus erythematosus (SLE) and serum lactate dehydrogenase (LDH) was examined in 28 patients with active SLE involving only the kidney. Serum levels of total LDH, LDH1, and LDH2 were significantly higher in the patients with diffuse proliferative lupus nephritis (World Health Organization class IV) than in those with milder renal disease (classes I through III and V). Total LDH levels showed good correlations with the activity index and the total pathologic score of the renal pathologic scoring system, and with the glomerular hypercellularity and overall deposits. The elevated level of LDH was mainly due to elevated levels of its isozymes LDH1 and LDH2. These results suggest that the elevation of serum LDH levels in patients with SLE reflects the renal pathologic changes due to lupus nephritis.