Osteomalacia

Question 1

inadequate levels of […], […] or […] […], or because calcium is […].

Bones become softer as a result of failed mineralisation and fracture more easily.

Answer 1

inadequate levels of calcium, phosphate or vitamin D, or because calcium is resorbed.

Bones become softer as a result of failed mineralisation and fracture more easily.

Question 2

Features

[…] […] (typically […] […], pelvis and lower […])

[…] and […] (particularly affecting […] and […] muscles) and impaired physical function

Answer 2

Bone pain (typically lower back, pelvis and lower extremities)
Myalgia and weakness (particularly affecting quadriceps and gluteal muscles) and impaired physical function

Question 3

Causes

• Vitamin […] deficiency (due to lack of […] to sunlight or poor […] of calcium)
• […] e.g. due to […] disease.
• […] […] […] - loss of […] leads to osteomalacia due to failed […].
• […] […] […] - renal […] can develop whereby a renal failure leads to reduced […] production. In this situation, phosphate levels […] due to failure of […].
• […] poisoning
• Drugs - e.g. anticonvulsants such as […] and […]
• […]-induced osteomalacia - paraneoplastic tumours can inhibit phosphate reabsorption leading to increased renal phosphate loss and subsequent deficiency.

Answer 3

Causes

• Vitamin D deficiency (due to lack of exposure to sunlight or poor intake of calcium)
• Malabsorption e.g. due to Coeliac’s disease.
• Renal tubular acidosis - loss of phosphate leads to osteomalacia due to failed reabsorption.
• Chronic kidney disease - renal osteodystrophy can develop whereby a renal failure leads to reduced 1-25-dihydroxycholecalciferol production. In this situation, phosphate levels rise due to failure of excretion.
• Cadmium poisoning
• Drugs - e.g. anticonvulsants such as carbamazepine and phenytoin
• Tumour-induced osteomalacia - paraneoplastic tumours can inhibit phosphate reabsorption leading to increased renal phosphate loss and subsequent deficiency.

Question 4

Typical findings biochemistry

Typical findings in osteomalacia:

Calcium
Phosphate
ALP
Parathyroid hormone
X-rays: […] lines (or zones) which are lucencies going part of the way through the bone

Answer 4

Typical findings in osteomalacia:

↓Calcium
↓Phosphate
↑ALP
↑Parathyroid hormone
X-rays: Looser lines (or zones) which are lucencies going part of the way through the bone

Question 5

Mx - vit […] supplementation
1. vitamin D level of < 25 nmol/L = deficiency, requires high dose treatment initially followed by maintenance treatment.

A vitamin D level of between 25-50 nmol/L = insufficiency, can be treated with long term maintenance therapy alone.

Question 6

Lifestyle advice

Answer 6

Safe sun exposure
Dietary intake of vitamin D and calcium
Long term maintenance supplements

Check Ca after 1 month