The influence of age on the pulmonary clearance of 99Tcm-DTPA radioaerosol.

Age-dependent changes of 99Tcm-DTPA radioaerosol transpulmonary clearance have been investigated in 49 healthy volunteers with an age range of 21-63 years. The clearance was uniformly increased in all smokers irrespective of age, but it showed a highly significant (p less than 0.001) decrease in non-smoking patients over 50 years. Several age-related changes in the ageing lung can contribute to this decreased clearance, but the reduced alveolar-capillary surface area available for the transport is probably the key factor. The practical implication of the results is the need to use age-related normal ranges when interpreting 99Tcm-DTPA radioaerosol clearance studies.