Pulmonary Function Loss in Diphenylhydatoin Therapy

¹ Chief, Pulmonary Function Laboratory, Fitzsimons Army Medical Center
² Assistant Chief, Allergy Service, Walter Reed Army Medical Center
³ Chief, Neurology Service, Fitzsimons Army Medical Center

Twenty-two women and 18 men, nonnative, longterm Denver residents^* ranging in age from 11 to 56 years, who took diphenylhydatoin (DPH) for two or more years, underwent pulmonary function testing. Forty-five percent of the subjects had reduced steady-state diffusing capacities (D_LCO) and abnormal blood gas tension during exercise. In addition, half of the subjects studied had widened resting and exercise alveolar-arterial oxygen (A-aDO₂) tension differences, and/or failed to increase D_LCO as expected with exercise. Macrocytosis and abnormal lung functions occurred together with remarkable frequency. However, lung function abnormalities persisted after the mean corpuscular volume (MCV) returned to normal, which suggests that macrocytosis and abnormal lung function are independent respondes to DPH in a susceptible host. Subjects receiving DPH before eight years of age exhibited abnormalities twice as often as those beginning therapy later in life.