Bone mineral density and L-thyroxine treatment in rapidly cycling bipolar disorder

The use of levothyroxine in higher doses, sufficient to suppress thyroid-stimulating hormone (TSH), has been shown in open and placebo-controlled crossover studies to be useful as an adjunctive treatment of the cycling behavior in patients with rapid-cycling bipolar disorder who are predominantly premenopausal women (Bauer and Whybrow 1990, 1991, Bauer et al 1994); however, we have been concerned about the risk of osteoporosis in this patient group, because exogenous thyroid hormone administration increases bone resorption and bone turnover (Baron and Braverman 1991). Indeed, some endocrinological studies indicate that externally administered thyroxine leads to decreased bone density in preand postmenopausal women (Baron and Braverman 1991 for review). Conversely, Franklyn et al (1992) recently found that premenopausal hypothyroid women treated with thyroxine did not develop a decrease in bone density in the vertebral and appendicular bone sites. There are no data on the effect of externally administered thyroxine on bone density on psychiatrically ill patients who receive this hormone to augment the effect of psychotropic medications. Hence, we now report a cross-sectional study undertaken to evaluate bone density in women with rapidly