PHARM Osteoporosis - Week 11

Question 1

Describe process involved in maintaining bone homeostasis.

Answer 1

In the maintenance of bone homeostasis, cytokines stimulates osteoblasts to express RANKL -> binds to RANK receptors on osteoclast progenitor cells in free form or membrane-bound on osteoblasts -> osteoclast bone resorption.

NB: Osteoblasts also synthesise & secrete OPG = osteoprotegerin – acts to protect bone from breakdown, by competitively binding to RANKL (in place of RANK).

Question 2

Risk factors for osteoporosis

Answer 2

• Increase PTH
• Increased RANKL
• Decreased OPG
• Decreased oestrogen
• Decreased calcium/Vit D
• Decreased TSH
• Previous minimal trauma fractures
• Oral corticosteroid use
• RA – due to medications, mentioned below
• High alcohol intake
• Current smoking Hx
• FHx of low trauma fractures (esp of spine/hip)
• Early menopause

Medications incl: glucocorticoids, thyroid hormones, heparin, some anti-epileptic drugs, gonatoropin-releasing hormone agonist/analogues, aromatase inhibitors, thiazolidinediones.