Biochemical studies in paraplegic renal stone patients. 1. Plasma biochemistry and urinary calcium and saturation

Renal stone disease is a common problem in patients with spinal cord injury. The factors responsible are thought to include hypercalciuria and chronic urinary infection. There have, however, been no comparative studies of urinary composition in patients with neuropathic bladder with and without renal stone disease. Blood, 24-h urine samples and circadian variation of urinary composition were studied in male paraplegic patients with renal stone disease accompanied by urinary infection and in similar patients without stone disease with and without urinary infection. Two categories of stone patients were recognised, according to whether or not urinary oversaturation with magnesium ammonium phosphate occurred. The urine of all stone patients was oversaturated with calcium phosphate for part of each day. Urinary calcium was elevated in 16% and plasma urate in 30% of the paraplegics studied.