Serum Uric Acid Levels in Psoriatic Arthritis

Abstract

SUMMARY Serum uric acid levels were determined in patients with psoriatic arthritis on and off medication, with rheumatoid arthritis on no medication likely to alter serum values, and in patients with uncomplicated psoriasis. Values in males were higher than those in females. A larger prevalence of values above the normal range were seen in males with psoriatic arthritis on uncontrolled medication (13-5 %) and in males with rheumatoid arthritis (12%) than in the other groups. The means for both these groups were around the midpoints of the normal range. These findings suggest that hyperuricaemia is not a common characteristic of psoriatic arthritis.Hyperuricaemia has been generally accepted as a frequent accompaniment of psoriasis and psoriatic arthritis. This association was first noted by Herrmann et al. (1930), who reported levels of uric acid above the upper limit of normal in 44 of 140 patients with psoriasis, especially in those with arthritis. Other authors reported similar findings (Steinberg et al., 1951;Tickner and Mier, 1960;Baumann and Jillson, 1960;Eisen and Seegmiller, 1961;Beveridge and Lawson, 1967;Pokorny and Resl, 1968;Solanet and Shulman, 1972). The prevalence of hyperuricaemia varied in these series from 21 to 50 %, the increase being more marked in males and in patients with arthritis. Eisen and Seegmiller (1961) found correlation of the serum uric acid level with the extent of skin involvement, and it has been postulated that the hyperuricaemia results from increased purine synthesis from the rapid epidermal cell turnover. However, their work with radioactively labelled glycine showed a pattern of turnover resembling primary rather than secondary gout.Further evidence for the association was reported by Kaplan and Klatskin (1960) who described 3 patients with psoriasis, gout, and sarcoidosis. However, Lea et al. (1958) found no difference between the values of 19 psoriatic patients and controls. Schattenkirchner (1970) found no increase in the frequency of raised serum uric acid levels in psoriatic arthritis compared with seronegative chronic polyarthritis, and Little et al. (1975) found that in patients with severe psoriasis, with or without arthritis, the mean serum uric acid levels were Accepted for publication August 19, 1976 Correspondence to Dr. J. R. Lambert, Rheumatism Research Unit, 36 Clarendon Road, Leeds LS2 9PJ in the middle of their normal range. A careful study was undertaken of our patients to try to resolve these conflicting reports. Materials and methodsThe study consisted of three parts. In the first, plasma uric acid levels were estimated in 115 patients (52 men, 63 women) with psoriatic arthritis fulfilling the criteria of Moll and Wright (1973). No account was taken of medication. Values were compared with the laboratory range of normal.In the second part of the study uric acid levels were measured on a group of 45 patients (13 men, 32 women) with psoriatic arthritis who had received only paracetamol for at least the preceding week. Values were compared with th...