Vitamin D deficiency and Osteomalacia Flashcards
What is Osteomalacia?
Disorder of mineralisation of bone matrix (osteoid)
What is Rickets?
Disroder of defective mineralisation of cartilage in the epiphyseal growth plates of children
What are the risk factors for Vitamin D Deficiency?
Lack of exposure to sunlight
Dietary Deficiency
Malabsorption
Decreased 25-hydroxylation of Vitamin D (due to liver disease, anticonvulsants)
Decreased 1a-hydroxylation of Vitamin D (due to chronic kidney disease, hypoparathyroidism)
Vitamin D Resistance
What are some Renal Phosphate Wasting Disorders?
Fanconi’s Syndrome
Renal Tubular Acidosis
Hereditary Hypophosphataemic rickets (X-linked or autosomal dominant)
Tumour induced osteomalacia
What is Fanconi’s Syndrome characterised by?
Phosphaturia
Glycosuria
Amino Aciduria
What is the epidemiology of Vitamin Deficiency and Osteomalacia?
Common in industrialised countries
More common in females
What are the presenting symptoms of Osteomalacia?
Bone pain (mainly in the axial skeleton)
Weakness
Malaise
What are the presenting symptoms of Rickets?
Hypotonia
Growth retardation
Skeletal deformities
What are the signs of Osteomalacia on physical examination?
Bone tenderness
Proximal Muscle weakness
Waddling gait
Signs of hypocalcaemia
What are the signs of Hypocalcaemia on physical examination?
Trousseau’s Sign
Chvostek’s Sign
What is Trousseau’s Sign?
Inflation of a blood pressure cuff to above the systolic pressure for > 3 mins causes tetanic spasm of the wrist and fingers
What is Chvostek’s Sign?
Tapping over the facial nerve causes twitching of the ipsilateral facial muscles
What are the signs of Rickets on physical examination?
Bossing of frontal and parietal bones Swelling of costochondral junctions (rickety rosary) Bow legs in early childhood 'Knock Knees' in later childhood Short Stature
What bloods would you do for Vitamin Deficiency and Osteomalacia and what might you expect?
Low or normal Ca2+ Low phosphate High ALP Low 25-hydroxy Vitamin D High PTH (secondary hyperparathyroidism) Check U&Es Check ABGs (for renal tubular acidosis) Increased phosphate excreting (in renal phosphate wasting)
What might you see on Radiographs for Vitamin Deficiency and Osteomalacia?
May appear normal
May show osteopaenia
Looser’s Zones
What are Looser’s Zones?
Wide transverse lucencies transversing part way through a bone, usually at right angles to the involved cortex and are associated most frequently with osteomalacia and rickets (aka pseudofractures)
What other investigation might you want to do for Vitamin Deficiency and Osteomalacia?
Bone biopsy after double tetracycline labelling
How does bone biopsy after double tetracycline labelling work?
Tetracycline is deposited at the mineralisation front as a band
After two course of tetracycline (separated by a few days), the distance between the bands of deposited tetracycline is reduced in osteomalacia
Not usually necessary for the diagnosis of osteomalacia
What is the management plan for Vitamin Deficiency and Osteomalacia?
Vitamin D and calcium replacement
Monitoring
Treat the underlying cause
What do we monitor in the management of Vitamin Deficiency and Osteomalacia?
24 Urinary Calcium Serum Calcium Phosphate ALP PTH Vitamin D
What are the possible complications of Vitamin Deficiency and Osteomalacia?
Bone deformities Hypocalcaemia can cause epileptic seizures Cardiac arrhythmias Hypocalcaemic tetany Depression Hypocalcaemia symptoms
What is the way to remember Hypocalcaemia symptoms?
CATs go NUMB
Convulsions
Arrhythmias
Tetany
NUMBness/paraesthesia
What is the prognosis for patients with Vitamin Deficiency and Osteomalacia?
Symptoms and radiological appearances improve with Vitamin D treatment
Bone deformities in children tend to be permanent
