Biochemical studies in paraplegic renal stone patients. 2. Urinary excretion of citrate, inorganic pyrophosphate, silicate and urate.

The urinary excretions of citrate, inorganic orthophosphate and pyrophosphate, silicate and urate were measured in 17 paraplegic patients with renal calculous disease associated with urinary infection, in 16 paraplegics with no history of urinary calculus and in 14 healthy control subjects. The paraplegics excreted less citrate, orthophosphate and pyrophosphate than the control subjects. The stone-formers excreted more urate than the paraplegics without stone disease, but less than the control subjects. There were significant positive correlations between urinary orthophosphate and pyrophosphate and between urinary silicate and 24-h urine volume. The possible roles of increased urate and diminished excretion of citrate and inorganic pyrophosphate in the aetiology of renal calculosis in paraplegic patients deserve further investigation.