Hyperaluminemia in renal failure: the influence of age and citrate intake

Following the occurrence of aluminum encephalopathy in four patients with chronic renal failure, we studied 34 azotemic patients seen during the same year and five volunteers who took varying combinations of aluminum hydroxide and an alkalinizing citrate (Shohl's) solution. We found that the four encephalopathic cases were older than the 34 azotemic patients (68 years +/- 14 SD, vs 50 +/- 13, p less than 0.05), had a higher mean serum aluminum value (727 micrograms/l +/- 320 vs 92 +/- 73, p less than 0.005), had taken more aluminum hydroxide (5 g/day +/- 0.9 vs 1.6 +/- 1.8, p less than 0.01), and more Shohl's solution (64 ml/day +/- 19 vs 20 +/- 29, p less than 0.01). In all 38 patients the serum aluminum values correlated directly with age (p = 0.01), aluminum hydroxide (p = 0.001) and concomitant citrate intake (p = 0.004). In the five healthy volunteers the 24-hour urinary aluminum excretion increased from a baseline of 22 micrograms +/- 19 SD to 167 +/- 109 (p = 0.05) during aluminum hydroxide intake, rising to 580 +/- 267 (p = 0.01) during the simultaneous intake of citrate and aluminum hydroxide. Corresponding serum aluminum values were 11 micrograms/l +/- 2 SD, 44 +/- 34 (p = 0.1), and 98 +/- 58 (p less than 0.05). Thus citrate seems to enhance aluminum absorption and may cause encephalopathy in patients with chronic renal failure, especially the elderly.