Urinary copper excretion in rheumatoid arthritis.

The pattern of urinary copper excretion in relation to urine osmolality (as shown by series of aliquots of urine) was studied in rheumatoid patients and in control groups. Rheumatoid patients showed an abnormal copper excretion pattern compared with nonrheumatoid subjects. This was not a direct function of the raised serum copper in rheumatoid disease. Measurements based on 24-hour series of aliquots of urine (as distinct from total pooled 24-hour collections) have been shown to be a useful and sensitive method for studying copper excretion patterns.