Effects of isotretinoin on bone turnover markers and bone mineral density in women with acne vulgaris and vitamin D deficiency: a preliminary study

The prolonged use of retinoids is associated with changes in bone turnover markers and toxic skeletal effects. Although the effect of short-term oral isotretinoin therapy on bone loss is not well established, caution is recommended when it is used in patients with metabolic bone disease. We examined prospectively the effect of short-term oral isotretinoin therapy on bone turnover markers and bone mineral density (BMD) in women affected by severe acne and vitamin D deficiency. Serum bone Tartrate-resistant Acid Phosphatase (TRACP), bone specific alkaline phosphatase (Bone ALP), calcium, phosphorus, parathyroid hormone (PTH) and 25-hydroxyvitamin D [25(OH)D] were measured in 10 women at baseline, 6 weeks, and end of isotretinoin treatment. BMD was measured in 5 subjects at baseline and end of treatment. Mean serum 25(OH)D at baseline was 16.3  7.5 nmol/L. Mean TRACP and Bone ALP increased at end of treatment but this was only statistically significant for TRACP (1.18, 1.13, 1.64 U/L; P<0.001). Mean calcium decreased slightly at end of treatment but no significant changes occurred in PTH, 25(OH)D and phosphorus. BMD decreased in all studied patients at the femur (range 2.5 to -7.6%), and in all but one patient at the lumbar spine (range +3.2 to -6.8%). Mean BMD decreased at all measured sites but this was statistically significant only for the femur (-5.3  1.9%; P=0.002). Our preliminary study suggests that short-term oral isotretinoin therapy in women with vitamin D deficiency is likely associated with increased bone resorption and decreased BMD. Correction of vitamin D deficiency may be necessary before starting isotretinoin therapy.