P. M. Davies, L. Fairbanks, K. Safranow
Jan 6, 2006
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Journal
Urological Research
Abstract
An unusual case with kidney stones composed mainly of 1-methyluric acid is described. The patient, a Caucasian male of Celtic descent, reportedly drank at least eight cups of coffee per day and had a long history of rheumatoid arthritis, gouty attacks and renal colics—the latter attributed to nephrocalcinosis and analgesic nephropathy. He was treated with allopurinol. At 54 years, a bilateral nephrolithotomy was performed. Stone samples were analysed by thermogravimetry and infrared spectroscopy and reported to be 12–25% calcium oxalate, the remainder being organic uric acid-like material. Analysis of the extracts by HPLC confirmed that the organic material contained 67% of 1-methyluric acid and 33% of uric acid. Possible mechanisms leading to the precipitation of 1-methyluric acid from urine are discussed. We conclude that the high caffeine intake resulted in extremely elevated urinary concentrations of 1-methyluric acid favouring the formation of 1-methyluric acid stones.