Uric acid excretion in the relatives of patients with gout.

The patients all had a diagnosis of primary gout, i.e. they had a characteristic history of acute episodic arthritis with a serum uric acid level above 6 mg./100 ml. and no evident underlying cause for hyperuricaemia. The investigation was carried out before treatment with uratelowering drugs was started. The nature of the study was explained to them and to as many as possible of their adult first-degree relatives, and all the participants were carefully instructed in the details of a low-purine alcoholfree diet (National Institute of Health, Bethesda low purine diet: daily purine content approximately 200 mg.) which they took for 6 days. On the last day they collected a 24-hour urine sample in a provided container which they delivered within a few hours of completion, when a blood sample was also taken. Uric acid and creatinine levels in these samples were estimated by Technicon Auto-Analyzer. 46 patients with 107 adult relatives participated in the investigation. Of these patients, 33 had male relatives and 31 had female relatives, and figures from all these subjects were taken in the analysis relating to serum uric acid levels. Some patients and relatives were excluded from studies involving urine collections, either because creatinine clearance was less than 60 ml./min. (indicating either renal impairment or incomplete urine collection) or, in one instance, because dietary restrictions had clearly been disregarded. The final analysis relating to uric acid excretion therefore applied to 37 patients (36 men and 1 woman) and 96 relatives, of whom 42 were brothers, 40 sisters, 5 mothers, 3 fathers, 3 daughters, and 3 sons; 27 of the gout patients had male relatives and 26 had female relatives. Two of the relatives themselves had gout, but had not taken any treatment for several months.