Bone manifestations of thyroid disorders

Thyroid hormones affect the metabolism, proliferation, and differentiation of every cell in the body, skeletal tissue being no exception. Thyroxine influences all types of bone cells from osteoblasts and osteocytes to chondrocytes and osteoclasts. It is thus no wonder that disruptions in thyroid function can have a multitude of consequences on both the juvenile and the mature skeleton. Some of these thyroid conditions like resistance to thyroid hormones (RTH) are quite rare, while others are among the most common endocrinopathies both in children and in adults. Hyperthyroidism for example is among the most common causes of secondary osteoporosis, and in recent years, even variations in normal thyroid function have been linked to fracture risk. Therefore, it is vital for the practicing os-teologist to familiarize himself or herself with the relationship between different thyroid diseases and the bone. In our paper, we summarize the basics of the cellular actions of thyroid hormones, their role in the regulation of bone metabolism, and the clinical significance of the most common thyroid conditions for everyday practice.