Having an underactive thyroid, a condition called hypothyroidism, does not increase your risk
for bone loss and
osteoporosis. Taking the amount of thyroid hormone medicine needed to replace what your body’s thyroid is not making does not hurt your bones. *However, taking more thyroid hormone medicine than you need can cause bone loss. An excess of thyroid hormone is harmful to your bones.* This can be caused by an overactive thyroid, a condition called hyperthyroidism.