Hypoxemia is a risk factor for bone mass loss

Time-dependent changes of bone mass in ambulant chronic respiratory failure patients 60 or more years of age were compared between those on home oxygen therapy (HOT) and those still free of HOT (non-HOT). HOT (n = 31) showed initial PaO2 of slightly greater than 60 Torr and non-HOT (n = 32) had PaO2 moderately greater than 60 Torr (64.4 Torr vs 75.1 Torr). PaCO2 in HOT was significantly higher than that of non-HOT (44.8 Torr vs 40.0 Torr). There was no difference in pulmonary function test results. The whole bone mineral density (BMD) as adjusted by age and sex was significantly lower in the HOT group than that in the non-HOT. At endpoints of the follow-up period over 2 years or more, daily bone losses in the whole BMD, whole bone mineral content, and lumber BMD were significantly more accelerated in HOT compared with non-HOT. When the Wistar rats were pair-fed and their locomotion was limited, the animal group placed for 4 weeks under hypoxic air showed a reduction in BMD as compared with the control. We suggest that hypoxemia contributes to bone mass loss.