Osteoporosis: causes
Advancing age and female sex and significant risk factors for osteoporosis. Prevalence of osteoporosis increases from 2% at 50 years to more than 25% at 80 years in women.
There are many other risk factors and secondary causes of osteoporosis. We'll start by looking at the most 'important' ones - these are risk factors that are used by major risk assessment tools such as FRAX:
Other risk factors
Medications that may worsen osteoporosis (other than glucocorticoids):
Investigations for secondary causes
If a patient is diagnosed with osteoporosis or has a fragility fracture further investigations may be warranted. NOGG recommend testing for the following reasons:
The following investigations are recommended by NOGG:
Other procedures, if indicated
So from the first list we should order the following bloods as a minimum for all patients:
There are many other risk factors and secondary causes of osteoporosis. We'll start by looking at the most 'important' ones - these are risk factors that are used by major risk assessment tools such as FRAX:
- history of glucocorticoid use
- rheumatoid arthritis
- alcohol excess
- history of parental hip fracture
- low body mass index
- current smoking
Other risk factors
- sedentary lifestyle
- premature menopause
- Caucasians and Asians
- endocrine disorders: hyperthyroidism, hypogonadism (e.g. Turner's, testosterone deficiency), growth hormone deficiency, hyperparathyroidism, diabetes mellitus
- multiple myeloma, lymphoma
- gastrointestinal disorders: inflammatory bowel disease, malabsorption (e.g. Coeliac's), gastrectomy, liver disease
- chronic kidney disease
- osteogenesis imperfecta, homocystinuria
Medications that may worsen osteoporosis (other than glucocorticoids):
- SSRIs
- antiepileptics
- proton pump inhibitors
- glitazones
- long term heparin therapy
- aromatase inhibitors e.g. anastrozole
Investigations for secondary causes
If a patient is diagnosed with osteoporosis or has a fragility fracture further investigations may be warranted. NOGG recommend testing for the following reasons:
- exclude diseases that mimic osteoporosis (e.g. osteomalacia, myeloma);
- identify the cause of osteoporosis and contributory factors;
- assess the risk of subsequent fractures;
- select the most appropriate form of treatment
The following investigations are recommended by NOGG:
- History and physical examination
- Blood cell count, sedimentation rate or C-reactive protein, serum calcium,
- Thyroid function tests
- Bone densitometry ( DXA)
Other procedures, if indicated
- Lateral radiographs of lumbar and thoracic spine/DXA-based vertebral imaging
- Protein immunoelectrophoresis and urinary Bence-Jones proteins
- 25OHD
- PTH
- Serum testosterone, SHBG, FSH, LH (in men),
- Serum prolactin
- 24 hour urinary cortisol/dexamethasone suppression test
- Endomysial and/or tissue transglutaminase antibodies (coeliac disease)
- Isotope bone scan
- Markers of bone turnover, when available
- Urinary calcium excretion
So from the first list we should order the following bloods as a minimum for all patients:
- full blood count
- urea and electrolytes
- liver function tests
- bone profile
- CRP
- thyroid function tests