Osteomalacia & rickets
Osteomalacia & rickets
Osteomalacia is a metabolic bone disease characterised by incomplete mineralisation of mature organic bone matrix following growth plate closure.
Vitamin D deficiency is the most common cause and this may be linked to a history of limited sunlight exposure. Inadequate phosphate or calcium levels may also lead to osteomalacia and these may be secondary to malnutrition, malabsorption or impaired resorption or excretion (e.g. renal failure).
Rickets may be thought of as osteomalacia in children. Rickets is a metabolic bone disease characterised by defective mineralisation of the epiphyseal growth plate cartilage in children, resulting in skeletal deformities and growth retardation. Rickets and osteomalacia are different manifestations of the same underlying pathological process.
Osteomalacia vs osteoporosis
In osteomalacia the bone mass is normal, but the matrix to mineral ratio is increased, meaning there is less mineral in boneIn osteopenia and osteoporosis bone mass is decreased but the matrix to mineral ratio is not altered from normal bone.
Clinical features
| Osteomalacia | Rickets |
|---|---|
| Bone pain Proximal muscle weakness Spinal tenderness to percussion Pseudofractures (Looser's zones) Skeletal deformities
| Bowed limbs (especially tibia) Poor growth Bone pain Greenstick fractures Skeletal abnormalities
|
Investigations
- Calcium, phosphate, vitamin D and PTH levels
- Renal function
- Alkaline phosphatase
- 24 hour urinary calcium
- X-rays and DXA scan may be useful
ALP is high in the majority of osteomalacia patients except in those patients with hypophosphatasia
PTH is high in osteomalacia caused by vitamin D deficiency, renal failure, and hypocalcaemia.
PTH is high in osteomalacia caused by vitamin D deficiency, renal failure, and hypocalcaemia.
Management
- Vitamin D and calcium supplementation are the mainstay in most cases
- Identification and treatment of any underlying cause.