Bone densities in patients receiving isotretinoin for cystic acne

Background: Few studies have been done of bone densities in humans receivin g retinoids, despite a substantial amount of literature concerning retinoid -induced osteoporosis in animals. We prospectively measured bone density an d calcium metabolism in young men (aged 17-25 years) receiving oral isotret inoin for cystic acne and in a group of healthy volunteers (aged 19-26 year s). Observations: Compared with that in healthy control subjects, mean bone den sity was lower at all sites (spine, femoral neck, and Ward triangle) and wa s considerably more variable at the spine in young men with cystic acne eve n before treatment. Bone density at the Ward triangle decreased a mean of 4 .4% (P = .03) after 6 months of isotretinoin use (1 mg/kg of body weight). Four patients showed decreased density of more than 9% at the Ward triangle . The difference between the mean change in bone density in the patient gro up and in the control group was significant at the Ward triangle (P = .04) but not at the other sites, Measurements of calcium metabolism did not chan ge over time in either group. Conclusions: A loss of bone density occurring in the absence of measurable alterations of calcium metabolism is likely to be a direct effect of retino ids on bone. Further study of retinoid-induced osteoporosis in humans and o f bone density in patients with cystic acne is needed.