The vitamin D produced by the skin is inactive and has to be converted to an active form by the liver first then by the kidneys, a three step process. Osteoporosis Literally means porous bones. Females are more susceptible than males Estrogen levels fall after menopause, estrogen is important in stimulating the osteoblasts to form bone. Thin people are more susceptible. May lack sufficient amounts of lipids to go into estrogen formation.
Smoking decreases the levels of estrogen in the plasma.
Calcium deficiency Vitamin D deficiency Lack of exercise or too much exercise. Adequate diet and moderate exercise Post-menopausal women need estrogen replacement therapy and calcium supplements.