Patients with chronic obstructive pulmonary disease (COPD) tend to develop erythrocytosis to compensate for the chronic hypoxic state. This compensatory mechanism may result in increased blood viscosity, requiring extended oxygen therapy and repeated phlebotomies. Theophylline is effective in reducing hematocrit and erythropoietin levels in patients with erythrocytosis following renal transplantation. Oren and associates retrospectively and prospectively evaluated the possibility that theophylline would be beneficial in modifying erythrocytosis in patients with COPD.
In the retrospective study, hematocrit levels were found to be significantly lower in the 50 patients receiving theophylline, compared with the levels in the 61 patients not receiving this drug. Since oxygen saturation was similar in both groups, the normal hematocrit levels in the theophylline group could not be entirely explained by improved oxygen availability alone.
In the prospective study, arterial oxygen saturation did not significantly increase during theophylline therapy. However, hematocrit levels declined significantly in seven of eight patients after three months of theophylline therapy. The greatest response was observed in the three most severely polycythemic patients. Serum erythropoietin levels declined by 21 to 91 percent in five of the seven patients in whom this variable was studied. The most significant decrease in the erythropoietin level occurred in the patient with the most severe polycythemia. Of four patients who discontinued theophylline therapy after three months, three had increased hematocrit levels within one month of stopping the medication.
The authors believe that, although the side effects of theophylline may limit its use in some patients, the possible beneficial effects demonstrated in this study may outweigh the side effects. They encourage the use of theophylline in patients with COPD-related erythrocytosis.