Erythropoietic response to hypoxaemia in diffuse idiopathic pulmonary fibrosis, as opposed to chronic obstructive pulmonary disease

The aim of this study was to assess the erythropoietic response to hypoxaem ia in patients with diffuse idiopathic pulmonary fibrosis (DIPF), and to sp eculate on the underlying mechanisms. Patients on an established chronic respiratory failure due to DIPF or chron ic obstructive pulmonary disease (COPD) were studied. The erythropoietic re sponse to hypoxaemia in both conditions was assessed. We studied 18 patient s with DIPF and 29 patients with COPD in respiratory failure in a stable st age, free from acute infection and congestive heart failure. Blood gases, e rythrocytic parameters, as well the serum levels of iron, ferritin and eryt hropoietin were determined. ll the DIPF patients studied, apart from two, had normal or subnormal haema tocrit values. The patients with COPD had an inconsistant response to hypox aemia; 12 had normal or subnormal haematocrit values and the remaining 17 w ere erythraemic. The mean value of erythropoietin (EPO) in both DIPF and CO PD patients was significantly higher than normal. In conclusion, patients with DIPF exhibit a lack of erythropoietic response to hypoxaemia, despite the augmented erythropoietin levels. This may refle ct a defective bone marrow erythropoietic response in DIPF patients. It is suggested that the pathophysiology of DIPF underlies this mechanism.