[Renal failure and carbon monoxide diffusing capacity of the lung (author's transl)]

Reduced carbon monoxide diffusing capacity of the lung (DLCO) is reported in patients with impaired renal function. Since DLCO also depends on the pulmonary capillary blood volume the role of renal anaemia was evaluated. Measurements were carried out in 43 azotaemic patients [serum creatinine (SKr) 1.5 to 14.0 mg/100 ml], without evidence of cardiovascular or pulmonary complications of uraemia, of SKr, haemoglobin concentration (Hb) and steady state DLCO. In the case of DLCO values allowance was made for body surface area and thoracic gas volume. The relation was studied of the corrected DLCO to SKr and to Hb. There was a higher statistical correlation between DLCO and Hb than between DLCO and SKr. After additional correction of DLCO for Hb, no correlation to SKr was found. It is concluded that the reduction in DLCO in uraemia is due largely to a low Hb and, hence, to renal anaemia rather than to uraemic damage of interstitial lung tissue.