title: Differences between Finnish and European reference values for pulmonary diffusing capacity.
abstract: OBJECTIVE
  To compare European (ECSC) and Finnish reference values for single-breath diffusing capacity for carbon monoxide (DL(CO)).
  
  
  METHODS
  Finnish reference values for DL(CO), specific diffusing capacity (DL(CO)/VA) and total lung capacity (TLC) were compared with ECSC reference values calculated for different age, height and weight groups. In addition, 10 healthy subjects performed the test with both the Finnish method (inhaled volume 90% of vital capacity, VC) and the ECSC method (inhaled volume 100% of VC).
  
  
  METHODS
  Percentual differences between the ECSC and Finnish reference values for DL(CO), TLC and DL(CO)/VA were calculated. The results of measurements of DL(CO) and TLC by using inhaled volume of 100% of VC and 90% of VC in 10 healthy subjects were compared.
  
  
  RESULTS
  The Finnish DL(CO) reference value for men was 3-12% and for women 8-20% smaller than the ECSC reference value. TLC calculated according to Finnish equations was 2-14% greater than that based on ECSC equations. The ECSC reference value for DL(CO)/VA was about 20% greater than the Finnish reference value in men and 30% greater than that in women. The 10 healthy subjects had significantly higher DL(CO) when measured according to the ECSC method as compared with the Finnish one (p < 0.004).
  
  
  CONCLUSIONS
  The Finnish reference values for DL(CO) were about 10% smaller, but TLC 10% and DL(CO)/VA 20-30% greater than ECSC reference values in subjects of the same age, height, weight and gender. The difference in DL(CO) is explained by the different inhaled lung volumes used in the two methods, the difference in lung volumes probably arising from ethnic differences in thoracic cavity.
authors.affiliation: Laboratory of Clinical Physiology, Meilahti Hospital, HUSLAB, Helsinki, Finland. paivi.piirila@hus.fi
authors.forename: Päivi
authors.initials: P
authors.lastname: Piirilä
authors.forename: Tommi
authors.initials: T
authors.lastname: Seikkula
authors.forename: Petteri
authors.initials: P
authors.lastname: Välimäki
mesh_terms: D000328:Adult; D000368:Aged; D001110:Arctic Regions / Q000453:epidemiology; D001827:Body Height; D005060:Europe / Q000453:epidemiology; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D044382:Population Groups; D011653:Pulmonary Diffusing Capacity / Q000592:standards*; D012016:Reference Values; D012737:Sex Factors; D014109:Total Lung Capacity; D044465:White People