People with the following factors are at high risk for osteoporosis: 1) old age; 2) female menopause; 3) maternal family history (especially family history of hip fracture); 4) low body weight; 5) low sex hormones; 6) smoking; 7) excessive alcohol or coffee consumption; 8) low physical activity; 9) dietary calcium and/or vitamin D deficiency (low light or low intake); 10) diseases affecting bone metabolism; 11) application of drugs affecting bone metabolism.