Dynamic spirometry and the lung transfer factor for CO (TLCO) were det
ermined in 41 non-smoking patients with sarcoidosis before and after s
teroid treatment. Dynamic spirometry revealed usual stage-dependent re
strictive and/or obstructive abnormalities; only maximal expiratory fl
ow rate at 75% FVC (MEF(75)) was significantly increased after steroid
treatment in stage 2 patients. The new finding is that TLCO was incre
ased in stage 1 [on average 21% above the predicted values (p.v.)], bu
t it was decreased in stage 2 (11% below p.v.) and stage 3 (27% below
p.v.). The increase in TLCO in stage 1 was predominantly caused by an
increase in TLCO membrane component (Dm) (33% above p.v.), while the p
ulmonary capillary blood volume (Vc') increased less (19% above p.v.).
Steroid treatment significantly reduced TLCO, Dm and Vc' in stage 1 (
for 14, 17 and 18% of the respective baseline values), whereas it caus
ed TLCO and Dm increases in stage 2 (for 8 and 10% of the respective b
aseline values). In conclusion, a TLCO in pulmonary sarcoidosis may no
t only be decreased in its advanced stages, but also exhibit increased
values, which appeared related to the subclinical inflammatory reacti
on in the stage 1 patients.