Osteoporosis
28 October 2019 13:10
~ REDUCED bone mineral density but NORMAL bone. T-score < -2.5 SD
Osteopenia: -1 > T-score > -2.5
Pathophysiology
• Commonest bone disease
• Micro-architectural deterioration of bone tissue → increased risk of fracture
○ Widening of Haversian canals
○ Thinning of cortisol bone
○ Decrease in no. of trabeculae in spongy bone
• Age-related decline in bone mass after peak
○ Due to imbalance in bone remodelling cycle (osteoclasts remove bone
faster than osteoblasts make)
○ Especially in women after menopause due to oestrogen deficiency
• Environmental factors (exercise, calcium intake) during adolescence and growth
help maximise peak bone mass; smoking and heavy alcohol have detrimental
effect on BMD
• Glucocorticoid-induced
○ Mechanism: inhibit bone formation; cause apoptosis of osteoblasts and
osteocytes
§ Can also be due to inhibition of intestinal calcium absorption,
increased renal excretion of calcium and secondary
hyperparathyroidism → stimulates osteoclastic bone resorption
○ Much lower risk with inhaled glucocorticoids
Peak Bone Mass Bone loss
Genetics (70-80%) Genetics
Body weight Immobility
Sex hormones Sex hormone deficiency
Diet Diet
Exercise Diseases
Drugs (corticosteroids, aromatase
inhibitors, glitazones)
Risk factors
• Major (FRAX)
○ Age
, Risk factors
• Major (FRAX)
○ Age
○ Female
○ Smoking
○ Low BMI (obesity is protective)
○ Alcohol excess
○ Glucocorticoids
○ Rheumatoid arthritis
○ Parental hip fracture
• Others
○ Caucasians and Asians
§ Africans have ↑bone mass
○ Sedentary lifestyle
○ Premature menopause
○ GI disorders
§ IBD, malabsorption (e.g. Coeliac), gastrectomy, liver disease
○ Endocrine disorders
§ Hyperthyroidism, hypogonadism (Turner's, testosterone deficiency),
growth hormone deficiency, hyperparathyroidism, Kleinfelter's,
Cushing's, diabetes
○ Multiple myeloma, lymphoma
○ Chronic kidney disease
○ Osteogenesis imperfecta, homocystinuria
○ Drugs
§ Heparin
§ Levothyroxine
§ Glitazones
§ Aromatase inhibitors
○ Pregnancy
§ Typically presents with back pain & multiple vertebral fractures
during 2nd or 3rd trimester
§ Rare; cause unknown
Clinical features
~ Low BMD does NOT cause symptoms until fracture occurs
• Pain, local tenderness, deformity
○ Hip: unable to weight-bear, shortened + externally rotated limb on
affected side
• Fragility fractures
○ Fall from standing height or less
§ Esp. vertebrae, shoulder blades, ribs (mainly spongy bone)
28 October 2019 13:10
~ REDUCED bone mineral density but NORMAL bone. T-score < -2.5 SD
Osteopenia: -1 > T-score > -2.5
Pathophysiology
• Commonest bone disease
• Micro-architectural deterioration of bone tissue → increased risk of fracture
○ Widening of Haversian canals
○ Thinning of cortisol bone
○ Decrease in no. of trabeculae in spongy bone
• Age-related decline in bone mass after peak
○ Due to imbalance in bone remodelling cycle (osteoclasts remove bone
faster than osteoblasts make)
○ Especially in women after menopause due to oestrogen deficiency
• Environmental factors (exercise, calcium intake) during adolescence and growth
help maximise peak bone mass; smoking and heavy alcohol have detrimental
effect on BMD
• Glucocorticoid-induced
○ Mechanism: inhibit bone formation; cause apoptosis of osteoblasts and
osteocytes
§ Can also be due to inhibition of intestinal calcium absorption,
increased renal excretion of calcium and secondary
hyperparathyroidism → stimulates osteoclastic bone resorption
○ Much lower risk with inhaled glucocorticoids
Peak Bone Mass Bone loss
Genetics (70-80%) Genetics
Body weight Immobility
Sex hormones Sex hormone deficiency
Diet Diet
Exercise Diseases
Drugs (corticosteroids, aromatase
inhibitors, glitazones)
Risk factors
• Major (FRAX)
○ Age
, Risk factors
• Major (FRAX)
○ Age
○ Female
○ Smoking
○ Low BMI (obesity is protective)
○ Alcohol excess
○ Glucocorticoids
○ Rheumatoid arthritis
○ Parental hip fracture
• Others
○ Caucasians and Asians
§ Africans have ↑bone mass
○ Sedentary lifestyle
○ Premature menopause
○ GI disorders
§ IBD, malabsorption (e.g. Coeliac), gastrectomy, liver disease
○ Endocrine disorders
§ Hyperthyroidism, hypogonadism (Turner's, testosterone deficiency),
growth hormone deficiency, hyperparathyroidism, Kleinfelter's,
Cushing's, diabetes
○ Multiple myeloma, lymphoma
○ Chronic kidney disease
○ Osteogenesis imperfecta, homocystinuria
○ Drugs
§ Heparin
§ Levothyroxine
§ Glitazones
§ Aromatase inhibitors
○ Pregnancy
§ Typically presents with back pain & multiple vertebral fractures
during 2nd or 3rd trimester
§ Rare; cause unknown
Clinical features
~ Low BMD does NOT cause symptoms until fracture occurs
• Pain, local tenderness, deformity
○ Hip: unable to weight-bear, shortened + externally rotated limb on
affected side
• Fragility fractures
○ Fall from standing height or less
§ Esp. vertebrae, shoulder blades, ribs (mainly spongy bone)
