Parathyroid hormone is produced by the parathyroid gland located behind the thyroid gland. As the calcium level in the blood increases, there is a feedback mechanism to slow absorption and osteoclast activity. Increased blood calcium will shut off parathyroid hormone secretion. At the same time the forth factor, calcitonin, is released from the thyroid gland. Calcitonin has the opposite effect of parathyroid hormone, it decreases calcium absorption.
Osteoporosis is the result of long-term calcium imbalance.
Over a period of decades, calcium is robbed from bones to maintain blood levels if dietary or absorption levels are not adequate. Clinical Signs of Osteoporosis Osteoporosis causes a decrease in bone density. This decrease is not normally diagnosed by X-ray analysis or normal medical examination until it is well advanced. Bone fracture is one of the most common ways of realizing osteoporosis is a problem. The most common sites of fracture are the wrist, hip, and vertebrae.