title: Substance P: correlation of CSF and plasma levels.
abstract: OBJECTIVE
  To determine the correlation between cerebrospinal fluid and plasma concentrations of substance P.
  
  
  METHODS
  37 patients undergoing lumbar puncture for various diagnostic purposes.
  
  
  METHODS
  Samples of cerebrospinal fluid and blood were obtained at the same visit. Substance P was measured by radioimmunoassay technique. At least 4 separate measurements were conducted on each sample to insure accuracy.
  
  
  RESULTS
  The mean plasma SP level was 1.195 (+/- 1.1). The mean cerebrospinal fluid substance P level was 1.075 (+/- .07). There was a statistically significant positive correlation between substance P level in the plasma and cerebrospinal fluid. The Pearson correlation coefficient was 0.656 (P < .0001) and the Spearman correlation coefficient was 0.698 (P < .0001).
  
  
  CONCLUSIONS
  Plasma substance P levels closely correlate with cerebrospinal fluid substance P levels. This will simplify the measurement of substance P in the evaluation of therapeutic agents for headache.
authors.affiliation: Cleveland Clinic Foundation, OH 44195-5039.
authors.forename: J W
authors.initials: JW
authors.lastname: Clark
authors.forename: P D
authors.initials: PD
authors.lastname: Senanayake
authors.forename: G D
authors.initials: GD
authors.lastname: Solomon
authors.forename: C
authors.initials: C
authors.lastname: Gallagher
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006261:Headache / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay; D013373:Substance P / Q000097:blood / Q000134:cerebrospinal fluid*
chemical_list: D013373:Substance P