Osteomalacia

Question 1

What is osteomalacia?

Answer 1

‘Soft bones’
Impairment of mineralisation
(Rickets is the equivalent in children)
Majority arises from disturbance in vit D and phosphate metabolism

Question 2

Risk factors of osteomalacia?

Answer 2

Vit D deficiency - too frail too go outside, wear clothing that covers lots of skin, dark skin
Partial gastrectomy/intestinal malabsorption
Chronic liver disease/chronic renal failure
Anticonvulsant medication
Strict diets e.g. lacto vegetarian
Excessive sunblock
Rare hereditary causes

Question 3

What are the clinical features of osteomalacia?

Answer 3

Bone pain
Skeletal deformities
Muscle weakness
Fracturing
Lethargy, tetany and convulsions due to hypocalcaemia
Bowing of legs
Partial fractures called looser’s zones

Question 4

What are the investigations for osteomalacia?

Answer 4

Low/normal Ca
Low/normal phosphate
Raised serum alkaline phosphatase
Low serum vit D
Raised PTH
Low urinary Ca excretion
25-OHD usually <30nmol/l and PTH >6.9pmol/L
X-rays - Looser zones, psuedofractures (small radiolucent Ines across bone)
Bone biopsy - increased osteoid with deficient mineralisation

Question 5

What is the treatment/management for osteomalacia?

Answer 5

Vit D replacement - cholecalciferol (D3) as high loading dose and lower maintenance dose.
Ca supplements to speed up bone healing
Sunshine
Moderating alcohol consumption
Not smoking
Exercising
Healy weight

Question 6

Hereditary forms of osteomalacia/rickets?

Answer 6

Hereditary vit D resistant rickets:
- autosomal dominant hypophosphataemic rickets (ADHR)
- hypophosphataemic vit D resistant rickets/ x-linked hypophosphataemia (XLH)
- psuedovitamin D deficiency rickets

Question 7

Acquired form of rickets/osteomalacia?

Answer 7

Tumour-induced osteomalacia/ oncogenic hypophospataemic osteomalacia