Osteoporosis is an adverse effect of prednisolone therapy, although no study has 
been conducted on myasthenia gravis patients receiving high-dose prednisolone. 
We measured bone density in 36 patients (26 females and 10 males) who had 
undergone long-term prednisolone administration, and found a decrease in bone 
density in 31% of female patients and osteoporosis in only 11.5% (three cases). 
This frequency is lower than the presumptive rate of the general population in 
Japan (22.6%). No osteoporosis was detected in male patients. In conclusion, 
prednisolone-treated patients with myasthenia gravis have an acceptable risk of 
bone loss if prophylactic medication is administered.