Calcium deficiency can lead to osteomalacia and osteoporosis, but osteomalacia and osteoporosis are not always caused by calcium deficiency. Osteomalacia can be caused by long-term chronic strain injury, bone degeneration with age, etc. It can also be caused by local inflammation, and calcium deficiency is one of the more common causes. Osteoporosis can be caused by the loss of bone mass due to old age. There can also be osteoporosis due to disuse, metabolic osteoporosis due to abnormal systemic hormone levels, and osteoporosis due to calcium deficiency. Therefore, calcium deficiency is one of the causes of both diseases, but not both diseases are caused by calcium deficiency.