Rickets and Osteomalacia

Question 1

Rickets and Osteomalacia define:

Answer 1

Rickets and Osteomalacia are the conditions that develop when people are Vitamin D deficient

Rickets = children
Osteomalacia = adults

Question 2

Main Function of Vitamin D?

Answer 2

• ↑ed intestinal Ca2+ absorption
• bone formation
• bone mineralisation
• bone remodelling stimulated
• ↓ed renal loss of Ca2+
• Ca2+ mobilisation from bone

Question 3

Difference between Rickets and Osteomalacia?

Answer 3

-Children’s bones are still growing, thus vitamin D deficiency manifests differently in children.

Question 4

Vitamin D Synthesis:

Answer 4

When 7-dehydroxycholesterol within the skin is exposed to UV-B light from the sun it synthesizes into previtamin D3. As a fat-soluble vitamin, dietary vitamin D is incorporated into chylomicrons and transported via lymphatics into the venous circulation. Some of the dietary vitamin D is extracted by adipose tissue and muscle, but the remainder and most of the endogenously synthesised vitamin D is transported to the liver. At the liver it is metabolised by enzymes vitamin D 25-hydroxylases (hydroxylation) into 25-hydroxy vitamin D. This is then converted into the biologically active form of vitamin D (1, 25- dihydroxyl-vitamin D3 in the proximal tubule of the kidney.

Question 5

Rickets and osteomalacia classification:

Answer 5

• Vitamin D deficiency
• ↓ed 25 (OH) D3 synthesis
• ↓ed 1, 25 (OH)2 D3 synthesis
• Defective action of 1,25(OH)2 D3
• Other e.g. Familial renal tubular defects etc

Question 6

Rickets and osteomalacia classification Vitamin D Deficiency:

Answer 6

1. dietary lack
2. increased intake of phytates
3. increased phosphate intake
4. decreased exposure to sunlight
5. malabsorption syndromes

Question 7

Rickets and osteomalacia classification, ↓ed 25 (OH) D3 synthesis:

Answer 7

1. liver disease

2. drugs which affect liver metabolism

Question 8

Rickets and osteomalacia classification, Defective action of 1,25(OH)2 D3:

Answer 8

ie the hormone is either:

 i. abnormal : vitamin D administration is curative
 ii. absent/defective: vitamin D receptors (ie vitamin D independent) administration of vitamin D is not curative.

Question 9

Rickets and osteomalacia classification, Other

Answer 9

eg. familial renal tubular defect

Question 10

Rickets pathological manifestation

Answer 10

• Defective calcification of growing bone
• Hypertrophy of epiphyseal cartilage
• Cessation of diaphyseal calcification
• Bone resorption in diaphyses

Question 11

Fontanel closure:

Answer 11

• The posterior fontanelle generally closes2to3months after birth;
• The sphenoidal fontanelle is the next to closearound 6 monthsafter birth;
• The mastoid fontanelle closes next from6to18 monthsafter birth
• The anterior fontanelle is generally the last to close between18–24 months.

Question 12

Rickets in neonates SSX:

Answer 12

• Restless
• Poor sleep
• Decreased skull mineralisation (craniotabes)

Question 13

Craniotabes

Answer 13

is softening or thinning of the skull in infants and children, which may be normally present in newborns. It is seen mostly in the occipital and parietal bones. The bones are soft, and when pressure is applied they will collapse underneath it.

Question 14

Rickets in Older infants:

Answer 14

• Delayed sitting/crawling
• Bossing (rounded eminence) of skull bones
• Costochondral beading (rachitic rosary)
• Delayed fontanelle closure

Question 15

Frontal Bossing:

Answer 15

Definition: abnormal prominence of the forehead

Bossing in rickets is due to the premature closure of the anterior portion of the sagittal suture, resulting in compensatory expansion of the frontal diploe
•A build up of excess of osteoid is also thought to add to the thickening of the frontal bone

Question 16

Rachtic Rosary / Costochondral veading

Answer 16

The prominent knobs of bone at the costochondral joints of rickets patients are known as a rachitic rosary or beading of the ribs

Question 17

Rickets Wrist enlargement?

Answer 17

Long bones, laying down of uncalcified osteoid below the growth plate leads to metaphysial enlargment & spreading
This results in a knobby deformity, which is seen on xray as metaphysial cupping & flaring
The expansion of the growth cartilage contributes to the clinical deformity

Question 18

Rickets in 1-4 year olds

Answer 18

• Enlargement of epiphyseal cartilages at the distal end of: the radius, ulna, tibia and fibula
• Kyphoscoliosis (vertebral softening)
• Bowleg
• Delayed walking

Question 19

Rickets >4

Answer 19

• Pain on walking
• Bowlegs
• Knock-knees

Question 20

Rachitic tetany?

Answer 20

-vitamin D in calcium homeostasis is to increase calcium absorption from the intestine. An abnormal condition characterized by periodic painful muscular spasms and tremors, caused by faulty calcium metabolism

Question 21

Rickets Radiological Findings

Answer 21

• Precede clinical signs

- Occur in 3rd -4th month of life

Question 22

Rickets Radiological Observations:

Answer 22

• Metaphysial cupping & flaring: normal forces acting on weak bone, metaphysis is attached to an abnormally widened/enlarged epiphysial growth plate.
• Spotty Rarefaction (reduced density) at diaphyseal ends: Cessation of diaphyseal calcification, Bone resorption in diaphyses
• Distance between the end of radius and metacarpal bones seems increased because the bone ends are not mineralised: Defective calcification of growing bone, hypertrophy of cartilage
• Bending bones: Uncalcified osteoid of growing bones coupled with pressure from gravity and upper body causing bending causing bowed legs

Question 23

Osteomalacia Radiological observations:

Answer 23

• Demineralisation especially in: spine pelvis and lower extremities (pseudo-Fruactures, incomplete ribbon-like demineralisation of the cortex)
• Bone softening results in : Bowling of long bones, vertical shortening of vertebrae, flattening of pelvic bones
• Kyphosis

Question 24

Laboratory Findings of osteomalacia low:

Answer 24

25 (OH)D3: Extremely low
1,25 (OH)2D3: Extremely low
Phosphate: Low
Alkaline Phosphatase: increased
CA2+: Decreased - normal
PTH: Increased
Urinary CA2+: Decreased

Question 25

Diagnosis:

Answer 25

• HX of inadequate Vitamin D intake
• X-rays
• Clinical picture

Question 26

DDX

Answer 26

• Hyperparathyroidism
• Hyperthyroidism
• Postmenopausal osteoporosis
• Cushing Syndrome

Question 27

Osteomalacia / Rickets Treatment:

Answer 27

• Adequate calcium and phosphate intake in addition to an adequate vitamin D intake
• If vitamin D production is defective, there is a need to administer the appropriate form of vitamin D
• If receptors are insensitive then treatment with very high doses of of vitamin D may not work.