S-erythropoietin levels decrease in patients with chronic hypoxia starting domiciliary oxygen therapy

Consecutive determinations of erythropoietin in serum (s-Epo) were made in ten patients with chronic hypoxia starting domiciliary long-term oxygen therapy (LTO). After 24 h of supplementary oxygen treatment there was a fall in the median s-Epo level from 11.3 to 4.4 IU.l-1 (p less than 0.01). The initial decrease in s-Epo in conjunction with oxygen treatment was not sustained after one and three months of LTO. S-Epo levels above the reference range (3.3-13.5 IU.l-1) were found in three patients before and during LTO and in another two patients during LTO. Markedly elevated s-Epo levels were found in two patients with hypoxia and hypercapnia at the time of blood sampling. A significant negative relationship was found between the arterial oxygen tension and the log value for the s-Epo level (r = 0.40, p less than 0.005). The s-Epo levels were found to be normal in half of the measurements in patients using oxygen less than 15 h daily, a fact that indicates that s-Epo measurements are probably not suitable as indicators of compliance with LTO.