Vitamin D Deficiency

Question 1

What is Osteomalacia?

Answer 1

It is a disorder of mineralisation of bone matrix (osteoid)

Question 2

What is Rickets?

Answer 2

It is a disorder of defective mineralisation of cartillage in the epiphyseal growth plates of children

Question 3

What are the risk factors for Vitamin D Deficiency?

Answer 3

Lack of exposure to sunlight
Dietary deficiency
Malabsorption
Decreased 25-hydroxylation of Vitamin D (Due to liver disease, anticonvulsants)
Decrease 1a-hydroxylation of Vitamin D (due to chronic kidney disease, hyperparathyrodisim)
Vitamin D resistance

Question 4

What is Renal Phosphate Wasting?

Answer 4

Loss of phosphate in urine

Question 5

What are some of the causes of Renal Phosphate Wasting?

Answer 5

Fanconi’s Syndrome
Renal tubular acidosis (type 2)
Hereditary hypophosphataemic rickets (X-linked or autosomal dominant)
Tumour indiced osteomalacia

Question 6

What is Fanconi’s Syndrome characterised by?

Answer 6

Phosphaturia
Glycosuria
Amino aciduria

Question 7

What is the epidemiology of Vitamin D Deficiency?

Answer 7

Common in industrialised countries

More common in FEMALES

Question 8

What are the presenting symptoms of Osteomalacia?

Answer 8

Bone pain (mainly in the axial skeleton)
Weakness
Malaise

Question 9

What are the presenting symptoms of Rickets?

Answer 9

Hypotonia
Growth retardation
Skeletal deformities

Question 10

What are the signs of Osteomalacia?

Answer 10

Bone tenderness
Proximal muscle weakness
Waddling gait
Signs of hypocalcaemia

Question 11

What are the signs of hypocalcaemia?

Answer 11

Trousseau’s Sign

Chvostek’s Sign

Question 12

What is Trousseau’s Sign?

Answer 12

Inflation of a BP cuff to above the systolic pressure for > 3 mins causes tetanic spasm of the wrist and fingers

Question 13

What is Chvostek’s Sign?

Answer 13

Tapping over the facial nerve causes twitching of the ipsilateral facial muscles

Question 14

What are the signs of Rickets?

Answer 14

Bossing of frontal and parietal bones 
Swelling of costochondral junctions (rickety rosary)
Bow legs in early childhood 
''Knock knees' in later childhiod 
Short stature

Question 15

What bloods do we do for Vitamin D Deficiency?

Answer 15

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)

Question 16

What do we see on a Radiograph for Vitamin D Deficiency?

Answer 16

May appear normal
May show osteopaenia
Looser’s Zones

Question 17

What are Looser’s Zones?

Answer 17

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)

Question 18

How do we do use Bone Biopsy for Vitamin D Deficiency and Osteomalacia?

Answer 18

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

Question 19

What is the management plan for Vitamin D Deficiency?

Answer 19

Vitamin D and Calcium Replacement
Monitoring
Treat the underlying cause

Question 20

What do we monitor for Vitamin D Deficiency?

Answer 20

24 hr Urinary Calcium 
Serum Calcium
Phosphate 
ALP
PTH
 Vitamin D

Question 21

What are the possible complications of Vitamin D Deficiency?

Answer 21

Bone deformities 
Hypocalcaemia can cause epileptic seizures 
Cardiac arrhythmias 
Hypocalcaemic tetany 
Depression 
Hypocalcaemia symptoms

Question 22

What are the Hypocalcaemia symptoms?

Answer 22

CATs go NUMB
Convulsions
Arrhythmias 
Tetany
Numbness/paraesthesia

Question 23

What is the prognosis for patients with Vitamin D Deficiency?

Answer 23

Symptoms and radiological apperances improve wirth Vit D treatment
Bone deformities in children tend to be permanent