Serum copper and zinc in rheumatoid arthritis and osteoarthritis.

Serum copper, zinc and caeruloplasmin levels were measured in 49 patients with active rheumatoid arthritis, in 33 patients with osteoarthritis and a group of blood donor controls. Serum copper and caeruloplasmin levels in the osteoarthritic patients were significantly higher and serum zinc levels significantly lower than in the blood donor controls. Although these differences could not be accounted for on the basis of age or drug administration neither did they correlate with a radiological grading of disease severity. Copper and caeruloplasmin levels were raised in the rheumatoid group as compared to both osteoarthritic and control groups. These were strong correlations between serum copper, caeruloplasmin, ESR and alpha 1 globulin levels in the rheumatoid patients. Although caeruloplasmin-bound copper accounted for most of the elevation in serum copper levels in the rheumatoid group, the calculated non-caeruloplasmin bound copper level was also elevated in rheumatoid, as compared to osteoarthritic patients. Serum zinc levels in the rheumatoid group were lower than in the control group but not significantly different to those in the osteoarthritic group.