Analysis of excretion fraction of uric acid.

Excretion fraction of uric acid (EFUA), is one of the most important hallmarks for diagnosis of familial juvenile hyperuricemic nephropathy (FJHN) and hereditary renal hypouricemia. EFUA was measured in 20 patients with FJHN. However, low excretion fraction (<6%) was found also in healthy FJHN family members and healthy controls (ref. ranges EFUA: men 6-12%, women 6-20%). Similar finding of low EFUA was reported recently. Distribution of EFUA was further studied in 2,416 healthy controls, which were selected from 6,000 samples and divided according to age. In conclusion, finding of low EFUA in family members is a risk factor for renal damage and indication for purine metabolic investigations with subsequent molecular biology analysis. As EFUA could be found also in healthy controls--it should be interpreted with care and other features of FJHN (such as hyperuricemia, progressive renal disease in family) should be taken to account.