Blood plasma fluoride in haemodialysed patients

Blood plasma fluoride was determined in 15 chronic haemodialysed patients (60.2 +/- 7.2 yr old) before and after a 4-h dialysis using dialysates with very low fluoride level, and in two control groups, the first of 20 healthy younger subjects (45.9 +/- 3.4 yr old), the second of 8 healthy older subjects (69.1 +/- 6.8 y old). Before haemodialysis the fluoride concentration (1.31 +/- 0.31 mumol/l; 24.8 +/- 5.9 micrograms/l), was higher than in both control groups (0.35 +/- 0.16 mumol/l; 6.6 +/- 3.1 micrograms/l and 0.44 +/- 0.16 mumol/l 8.4 +/- 3.0 micrograms/l, respectively). During dialysis, the mean fluoride concentration fell to 0.94 +/- 0.26 mumol/l, remaining however, significantly higher than in control subjects. The use of fluoride-free dialysates seems to partially compensate the effect of renal impairment since plasma fluoride is only moderately increased in these patients.