Rickets

Question 1

Definition

Answer 1

Metabolic bone disease due to failure of mineralization of osteoid tissue of the growing bones due to either:

y Defective intake or metabolism or function of vitamine D.

y Inappropriate calcium / phosphate ratio (usually due to hypophosphatemia, rarely due to calcium deficiency)

Question 2

Calcium deficiency with 2 ry hyperparathyroidism→normal or low ca

Answer 2

1. Nutritional vitamin D deficiency (Infantile rickets)
2. Secondary vitamin D deficiency due to:

o Malabsorption syndromes (Celiac rickets).

o Decreased liver 25-hydroxylase activity in chronic

liver disease

o Increased degradation e.g. with anti epileptic drugs.

3. Rickets with chronic renal failure (Renal osteodystrophy)
4. Vitamin D dependent rickets type I
5. Vitamin D dependent rickets type II
6. Calcium deficiency : nutritional , malabsorption or in

premature infant

Question 3

Phosphate deficiency without 2 ry hyperparathyroidism → normal ca level

Answer 3

1. Decreased phosphate intake

y Premature infants (rickets of prematurity)

2. Renal phosphate losses e.g.

y Familial hypophosphataemia.

y Fanconi syndromes

y Overproduction of phosphatonin e.g. Tumor-induced

rickets

Question 4

Vitamin D Deficiency Rickets → Predisposing factors

Answer 4

. - Commoner in winter : - Commonest age p 6 months - 24 month.

: - More in rapidly growing infant e.g. twins & preterm.

• Less in infants with arrested growth e.g. PCM & cretinism.

Question 5

Vitamin D Deficiency Rickets → etiology

Answer 5

A. Decreased vitamin D intake due to:

1. Lack of rich sources of vitamin D e.g. egg yolk, meat, fortified milks, fish liver oil.
2. Use of rachitogenic diet with:
   - Poor sources of vitamin D as fresh animal milk ,cereals and carbohydrates.
   - Poor sources of calcium as cereals ,and excess leafy vegetables
   - Inappropriate calcium /phosphate ratio as in fresh animal milk

B. Lack of access of ultra violet rays to the skin due

Question 6

Clinical picture → Early Rickets

Answer 6

1- Anorexia, irritability, & sweating of forehead

2- Craniotabes

• Skull bones yield under pressure p Ping - pong or egg shell crackling sensation.
• Due to thinning of inner table of the skull
• Disappear by the end of 1 st year.
• Detected by pressing over occipital or parietal bone

3- Rachitic rosaries: palpable enlargement of costochondral junctions (excess osteoid)

Question 7

Clinical picture → advanced Skeletal Changes

Answer 7

1. Head
   Large head ,Large anterior fontanel (delayed closure). Asymmetric skull; may be box shaped
   Frontal & parietal bones bossing due to excess osteoid
   Depressed nasal bridge
   Delayed teething, dental caries
2. Chest
   🌺Rachitic rosaries
   - Visible & Palpable.
   - Rounded, Regular, Non tender
   🌼Longitudinal sulcus p lateral to the rosaries
   🌻Harrison sulcus p transverse groove along costal insertion of the diaphragm Chest
   🌹deformities:
   * Pigeon chest p sternum & adjacent cartilages
   project forwards.
   * Funnel chest p depression of the sternum &
   flaring out of the lower ribs.

Question 8

Other skeletal deformities

Answer 8

3. Vertebral column : there may be
   a. Kyphosis: in dorsolumbar region
   - Smooth.
   - Apparent on sitting, disappear by lifting.
   - With compensatory lumbar lordosis
   b. Scoliosis: lateral curvature of the spine
4. Extremities
   a. Broadening of epiphysis of long bones especially at wrist & ankles.
   b. Marfan sign: transverse groove over the medial maleolus due to unequal growth of the two ossific centers.
   c. Deformities: Due to weight bearing on the soft bones; * Crawling infants:
   - Bowing of forearm.
   - Anterolateral curvature of femurs
   - Anteroposterior curvat1ure of legs * Walking child:
   - Bow legs(Genu varus)
   - Knock knees (Genu valgum)
   - Overextended knees(Genu recurvatum)

Question 9

Non Skeletal Manifestations

Answer 9

Manifestations:

1- Delayed motor milestones.

2- Abdominal distension (pot belly abdomen) ; with or without umbilical hernia

3- Ptosis of the liver & the spleen (also due to chest deformities).

4- Constipation p due to intestinal hypotonia.

Question 10

Complications of rickets

Answer 10

1- Respiratory infections & atelectasis due to:

a- Limited chest expansion.

b- Hypotonia of respiratory muscles → weak cough reflex.

2- Gastroenteritis due to intestinal hypotonia → stasis → 2 ry bacterial overgrowth.

3- Tetany : may occur in rickets with hypocalcaemia

4- Skeletal deformities: - Mild and early managed cases p reversible.

• Advanced and neglected cases p permanent.

5- Disproportionate short stature (Rachitic dwarfism)p due to deformities of spine, pelvis & limbs

6- Iron deficiency anemia is a common association ( Von-Jack anemia = anemia , rickets , lymphadenopathy and splenomegaly)

Question 11

Investigations → lab

Answer 11

o Serum calcium is normal, but may be low (normal = 9 – 11 mg/dl).
o Serum inorganic phosphrus (Ph.) is low (normal value = 4.5 – 6.5 mg/dl).
o Serum Calcium × Phosphate product is low (less than 30).
o Serum alkaline phosphatase enzyme (Alk. Phos.):
- High
- The most sensitive indicator of rachitic activity; due to osteoblastic activity
- Return to normal after complete healing of rickets.
o Serum Parathyroid hormone (PTH) p high.
o Serum 25 (OH) D 3 p low
o Serum 1.25 (OH) 2 D 3 p low in severe vitamin D deficiency

Question 12

Radiologic

Answer 12

Active rickets
The lower ends show
y Broadening ; widening of the distal end of the metaphysis
y Cupping or concavity ; metaphysis changes from a convex or flat surface to a more concave surface
y Metaphysis loses its sharp border ( Fraying ) y Wide joint space

The shaft shows y Rarefaction p q bone density y May be green stick fracture. y May be deformities

Question 13

Prevention

Answer 13

a. Vitamin D supplement usually as daily multivitamin
Dose: - For less than 1 year → 400 IU/day mainly for Breast feeders

• For above 1 year p 600 IU/day
  b. Advice for:
• Exposure of pregnant mothers and infants to sunlight
• Diet with adequate calcium and phosphorus(formula, milk , dairy products)
• Vitamin D and calcium supplement for pregnant and lactating mothers

Question 14

Curative treatment

Answer 14

a. Vitamin D3 :
* Oral : 2000 – 5000 IU/day for 4 - 6 weeks * Stoss (Shock) therapy :
- 300.000- 600.000 IU IM or oral for 2-4 doses over 1day
- Indicated if compliance is uncertain
Either strategy should be followed by daily vitamin D intake maintenance

b. Advice parents for:
- Advice about Diet and sunlight as before
- Avoid weight bearing in infants during active rickets.

c. Treat complications:
* Tetany * Deformities: osteotomy and reconstruction if severe and persistent.

After 4- 6 weeks of treatment: Look for criteria of improvement;

1. Radiologic : Appearance of zone of provisional calcification is the earliest finding.
2. Laboratory : Normalization of alkaline phosphatase indicates complete healing
3. Clinical: Improved muscle tone but skeletal manifestations may take a longer time ( Some skeletal signs may persist as large head , severe deformities, pigeon chest) Decision: Reduce vitamin D dose to the normal daily requirement (to avoid toxicity)

Question 15

Rickets with anti epileptic drugs

Answer 15

🌼Prolonged anti epileptic medicines ( phenytoin , phenobarbitone or carbamazepine ) → enzyme inducers → inactivation of 25 (OH) D3
🌼 Poor sun exposure or poor diet in neurologically disabled +
🌼 Clinical , lab and radiologic features of infantile rickets
Treatment: Oral calcium+ Sun exposure + 25 OH D3
Prevented by extra dose of vit D for all susceptible epileptics