Pulmonary diffusing capacity in healthy African-American and Caucasian children.

Previous studies of pulmonary diffusing capacity in healthy children primarily focused upon Caucasian (C) subjects. Since lung volumes in African-Americans (AA) are smaller than lung volumes in C subjects of the same height, diffusing capacity values in AA children might be interpreted as low or abnormal using currently available equations without adjusting for race. Healthy AA (N = 151) and C (N = 301) children between 5 and 18 years of age performed acceptable measurements of single breath pulmonary diffusing capacity for carbon monoxide (DLCO ) and alveolar volume (VA ) according to current ATS/ERS guidelines. The natural log of DLCO and VA were associated with height, gender, age, and race; AA children had lower DLCO and VA compared to C children. Adjustment of DLCO for Hemoglobin (Hgb) resulted in no significant difference in DLCO among these healthy subjects with normal Hgb. In summary, we report prediction equations for DLCO and VA that include adjustment for race (C; AA) demonstrating that AA have lower DLCO and VA compared to C children for the same height, gender, and age.