This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: NEET Jan 2020, Subject name: Gynaecology & Obstetrics
First line of treatment of osteoporosis in postmenopausal woman? 
Select and explain. 
A. Estrogen, B. Calcium and vitamin D supplementation, C. Bisphosphonates, D. Ulipristal
A: Estrogen
Answer: A: Estrogen 
Explanation: Hormone replacement therapy is cornerstone in both prophylaxis and treatment of osteoporosis in menopausal women. Estrogen delays and protects against osteoporosis by 50% in all skeletal and not limited to trabecular bones of spine, wrist and upper hip. Rest of the drugs used in H for osteoporosis are natural estrogens, progesterone, tibolone and raloxifene. Bisphosphonates may be used are primary treatment in late osteoporosis in postmenopausal women Bisphosphonates include: Alendronate, Risedronate, Ibandronate, Zoledronate. These agents chemically bind to calcium hydroxyapatite in bone and decrease bone resorption by blocking the function and survival but not the formation of osteoclast.