DEXA Scan

 Osteoporosis     - decreased bone mineral density that results in increased susceptibility to low trauma                                     fragility fractures.

                           - WHO defines it as 2.5 STD Deviation below peak bone mass (20 years old healthy                                     female average) as measured on DEXA scan. 


Risk factors     

                            1.Low impact fracture

                            2. New thoracic kyphosis

                            3. Early menopause (oestrogen blocks effect of PTH on osteoclast )

                            4. Family history of hip or vertebral fractures in first degree relatives < 65 years.

                            5. Predispositions - hypothyroid ,RA, Alcohol, Cushing's disease, Malignancy

                            6. Prolonged amenorrhoea in absence of pregnancy

                            7. Drugs; steroids,  thyroxine, heparin, phenytoin, chemotherapy


What tests results are given and how to interpret them ?
        

                         Z- score - SD from normal of that patient's age. 

                                           first we have to find percentage of normal bone density for that age.

                          T-score   - SD from normal from normal young adults 

                                            it should ne what they have at 40. >/= 90 considered normal.


                        Dexa Scan

Treatment of Osteoporosis drugs and mechanism of action. 

According to NICE guidelines ( National Institute of Health and Clinical Excellence)

                        1. Life-style changes 

                             Weight bearing exercises

                            decrease alcohol consumption

                            stopping alcohol

                            reducing fall risks 

                        2. Pharmacologic

                           1. Calcium ( 1500 mg ) and Vitamin D (800 U ) Supplements     

                            2. Postmenopausal < 65 years old with T-score > 3 or > 75 years old with osteoporotic                                 fractures 

                                 First line - -Bisphosphonates ,Alendronate 70 mg once a week.

                                  Second line - Strontium Ranelate 20mg once daily.

  Bisphosphonates - decrease osteoclastic resorption of bone. 

  Strontium Ranelate - increase proliferation of osteoblasts. Inhibit proliferation of osteoclasts. 

   Raloxifene - -SERM -attaches itself to oestrogen receptors on bone, stimulating production of new                             bone. 

three key elements of a strategy for osteoporosis

        High quality fracture care - co-ordinated multidisciplinary approach.

        High quality secondary prevention of fragility fracture - ensured by providing bone protection and        falls assessment 

        High quality information

   

Osteopenia - T-score ranging from -2.5 to -1.

                                          Treat with lifestyle changes. 

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