The chest X-ray in pulmonary capillary haemorrhage: correlation with carbon monoxide uptake.

Serial changes in carbon monoxide uptake (KCO or DLCO/VA) were used to monitor episodes of pulmonary capillary haemorrhage in Goodpasture's syndrome (13 cases), immune complex nephritis (three cases) and idiopathic haemosiderosis (one case). Air-space shadowing on the chest X-ray (on a scoring system 0 to 12) was assessed in the light of the changes of KCO. In 14 out of 27 episodes of bleeding, the rise and fall of KCO was matched in time by the appearance and disappearance of air-space shadowing on the chest X-ray. In six episodes the chest X-ray remained normal despite a rise of KCO. In two cases air-space shadowing appeared up to 48 h after the rise of KCO. On five occasions chest X-ray abnormalities preceded the rise of KCO but chest infection or fluid overload accounted for three of these. In cases with suspected pulmonary capillary haemorrhage, measurements of carbon monoxide uptake will provide additional information and will assist in the interpretation of the chest X-ray.