Calcium And Phosphate Metabolisms Flashcards
What is osteoporosis?
Loss of bone mass
What causes osteoporosis?
Endocrine
Malignancy
Drug induced
Renal disease
Nutritional
Age
How is osteoporosis diagnosed?
Measurement of bone mineral density (BMD)
Dual energy X ray absorptiometry (DEXA)
T score (number of SDs below average for young adult at peak bone density)
Z score (matched to age and group)
What are some endocrine causes of osteoporosis?
Hypogonadism - notably any cause of oestrogen deficiency
Excess glucocorticoids
Hyperparathyroidism
Hyperthyroidism
What are some treatments for osteoporosis?
- Adequate calcium and vitamin D intake
- appropriate excersice
- postmenopausal: HRT
- Biophosphates - inhibit function of osteoclasts
- PTH analogues
- Denosumab - human monoclonal antibody against RANK ligand
- Romozumab- human monoclonal antibody against sclerosis
What is osteomalacia?
Loss of bone mineralisation
What are the symptoms of osteomalacia?
Permanent deformities in bone growth
Diffuse aches and pains
Chronic fatigue
Weak bones
What are some signs of osteomalacia?
Low Ca, Pi
Elavataed alkaline phosphatase
PTH may be elevated
What are causes of osteomalacia?
Vitamin D
Mutations leading to errors in vitamin D metabolism
Hypophosphataemia
How is osteomalacia treated?
Vitamin D and calcium supply
What increases vitamin D3 production?
PTH
Low Ca
Low Pi
What decreases vitamin D production?
FGF-23
High Ca
High Pi
What is FGF-23?
A hormone secreted by osteocytes that regulates vitamin D metabolism
What are 3 disorders associated with FGF-23?
Oncogenic osteomalacia
X-linked hypophataemic rickets
Autosomal dominant hypophophataemic rickets
What is renal osteodystrophy?
A spectrum of conditions associated with bone lesions in renal failure
