Lead in cerebrospinal fluid and its relationship to plasma lead in humans.

Lead levels in whole blood, plasma and cerebrospinal fluid (CSF) were determined in 18 patients suffering from Amyotrophic Lateral Sclerosis (ALS) and in 21 subjects hospitalized for neurological investigations. No significant differences were found for blood, plasma and CSF lead concentration between the ALS group and the other patient group. The plasma lead-CSF lead mean ratio was greater than 1 in both groups, while in subjects with a slight degree of blood-CSF barrier impairment a significant decrease of the ratio was demonstrated. A significant relationship between plasma lead and CSF lead levels (r = 0.405; p less than 0.01), but not between whole blood lead and CSF lead levels, was established. Lead levels in CSF were also age-related (r = 0.485; p less than 0.05) in the group of patients not suffering from ALS. In subjects with normal blood-brain barrier permeability, lead in plasma is a good indicator of CSF lead concentration.