This document discusses rickets, a disease characterized by defective bone mineralization due to vitamin D deficiency or abnormal metabolism. It covers the sources and types of vitamin D, how vitamin D is metabolized in the body, and its actions in increasing calcium and phosphate absorption and bone mineralization. Symptoms of rickets are described including bone deformities, craniotabes, and rosary beads. Diagnosis involves physical exam findings, elevated alkaline phosphatase levels, and x-rays showing metaphyseal changes. Treatment is aimed at correcting the vitamin D deficiency through sunlight exposure or vitamin D supplementation. Prognosis is generally good with treatment but deformities may require orthopedic correction.

1. RICKETS
BY Dr.
HAMDY ABO HAGAR
ASSISTANT PROFESSOR OF
PEDIATRICS

2.  Defective mineralization of growing bones,
due to vitamine D deficiency or abnormal
metabolism.

3. Sources:
 A: Diets such as fats and
oils.
 B: Vitamin D supplements.
 C: Ultraviolet sunrays effect
on a precursor in the skin (7-
dehydrocholesterol).
Types:
 Vitamin D2 of plant origin
 Vitamin D3 of animal origin
and that naturally formed in
the skin.

4. Metabolism:
 After absorption from the gut or formation in
the skin, vitamin D passes through two steps
of activation before it becomes ready to act:
- In the liver: It is hydroxylated to 25-hydroxy
Vit D.
- In the kidney: It is furtherly hydroxylated to
1,25 dihydroxy Vit D (the active form).

5. Actions:
In the intestine: It increases absorption of Ca
and P.
In the kidney: It increases reabsorption of Ca
and P.
In bones: It stimulates mineralization of
bones.

8.  Zone of resting
cartilage (one
layer of cells).
 Zone of
proliferating
cartilage: regular
columns of cells
originating from
resting layer).

9.  Zone of degeneration (cells
become swollen with
glycogen, glycolytic enzymes
and alkaline phosphatase.
Calcium is deposited in the
matrix. It is sharply
demarcated in X ray film).
 Zone of ossification (blood
vessels invade the
developing bone with
ossification and remodeling
resulting in mature bone).

10.  Zone of proliferation increases and
becomes very vascular causing
enlargement of metaphyseal area and
invades the adjacent zone of
degeneration.
 Zone of degeneration fails to mineralize
and the newly formed tissue called
osteoid is excessively deposited and
being soft it gives way with pressure
causing bulging and deformity of
metaphyseal area of long bones (this is
responsible for flaring of the ends of long
bones and rachitic rosary).

11.  In the shaft: bone is resorbed and new
osteoid is formed around the shaft
from the periosteum
 During healing of rickets: a new line of
calcified bone (line of provisional
calcification) appears at the end of
zone of degeneration out standing
from rarefied osteoid then the area
between it and the diaphysis gradually
fills with normal density bone.

12. Active rickets:
 They occur early, are pathognomonic
and diagnostic, and help in follow up.
Distal ends of long bones appear
flared, frayed and cupped.
 Distance between the distal end of
radius and metacarpal bones appears
wider than normal (by the area filled
with osteoid).
 Diaphysis appears rarefied and may
show double contour or deformity.

13. Healing rickets:
Occurs 2-3 weeks after
successful treatment.
Appearance of the line of
provisional calcification at
the end of metaphysis,
then the osteoid in
between this line and
diaphysis gradually
ossifies.

14. Healed rickets:
Bone density returns to normal with slight
cupping remains as a stigma of previous
rickets.

16.  Serum alkaline phosphatase is elevated due to
over activity of osteoblasts during the formation of
excessive osteoid (normal 5-15 Bodansky units
/dl).
 Serum inorganic phosphorus is decreased (normal
4.5-6.5 mg/dl).
 Serum calcium is maintained within normal values
(9-11 mg/dl) due to compensatory hyperactivity of
parathyroid gland.
 Vitamin D and its metabolites are decreased.

17. Vitamin D deficiency rickets most
commonly occurs at the end of the first
year and during the second year of life.

18. 1.Craniotabes:
Occurs due to thinning of the inner
table of occipital bone under the
pressure of intracranial contents with
failure of mineralization.
It can be elicited by gentle pressure by
both thumbs of the occipital bone,
which produces a dent with crackling
sensation (ping pong ball like).
This can be elicited from 3 to 12
months of life.

19. 2. Rosary:
Enlargement of
costochondral junction of
ribs giving the
appearance of beads due
to excessive osteoid
formation.
3. Radiological finding of
active rickets.
4. Rise of serum alkaline
phosphatase enzyme.

20. Head:
 Bossing of skull: excessive
proliferation of cartilage at occipital
and parietal eminences makes the
skull looks like a box.
 Enlargement of head circumference.
 Delayed closure of anterior
fontanels, which remains widely
open.
 Delayed eruption of primary dentition
with possible enamel hypoplasia.

21. Thorax:
 Rosary beads.
 Longitudinal sulcus: appears lateral
to the rosaries due to compression
of rib cage by atmospheric pressure
at weakest point.
 Harrison's sulcus: A transverse
sulcus along the lower border of the
costal margin due to inward traction
of the ribs at sites of diaphragmatic
insertion.

22. Thorax:
 Forward protrusion of sternum
and adjacent costal cartilage.
 Everted costal margin below
Harrison's sulcus.
 The overall shape of the chest
wall is called “pigeon chest”,
which is nearly triangular in
cross section.

23.  Abdomen:
 Liver and spleen become palpable
due to deformed chest and weak
abdominal muscles. The abdomen
appears protruded.
 Pelvis:
 Pelvic inlet is narrowed by forward
protrusion of sacral promontory, while
pelvic outlet is narrowed by forward
projection of the coccyx.
 This might be very hazardous in
females during labor in the future.

24. Spinal column:
Correctable kyphosis in
the dorsal region and
lordosis in the lumbar
region due to muscle
weakness and laxity of
ligaments.
Scoliosis

25.  Extremities:
 Enlargement of metaphyseal region
especially at wrists and ankles
 Marfan's sign: transverse groove above the
medial and sometimes also the lateral
maleolus.
 Deformities of long bones due to weight
bearing.
 Greenstick fracture.

26. Rachitic dwarfism: due to
spinal and lower limb
deformities.
Weak muscles and lax
ligaments causing delayed
locomotor milestones.

27.  Respiratory: infections or atelectasis due to
chest deformities.
 GIT: diarrhea or constipation.
 Bony deformities or fractures.
 Anemia: due to chronic infection or
deficiencies.
 Tetany: due to hypocalcaemia in late cases
after exhaustion of parathyroids.

28. Usually good with improvement after
exposure to sun light in the morning or
afternoon or after administration of Vitamin
D.
Deformities improve with normal growth
but very slowly.
Sometimes, severe skeletal deformities
require orthopedic correction.

29.  Exposure to ultraviolet rays in
sunshine (10 to 20 minutes/day).
 Daily requirements of vitamin D are
400-800 i.u /day.
 For low birth weight infants, and
patients of malnutrition or
hypothyroidism during receiving
their specific treatment, 1000-1500
i.u /day are needed for the
accelerated rate of growth.

30. Oral Vitamin D in a dose of 1500-5000
i.u/day for 6-8 weeks.
Shock therapy: Vit D 600,000 i.u by I.M.
injection or orally single dose.
After 2-4 weeks, if no radiologic or
laboratory evidence of complete healing
occurs, the dose can be repeated.

32.  Vitamin D dependent type: due to defective 1-
alpha-hydroxylase in the kidney or failure of
end organ response to it.
 Familial hypophophatemic resistant rickets:
affects girls more, there is tubular defect in
phosphate retention resulting in excessive
urinary phosphate losses.
 Tubular defects such as Fanconi syndrome
with urinary loss of
phosphate, glucose, amino acids and
bicarbonates.

33. Chronic renal failure.
Acquired renal tubular damage, e.g. drugs.
Malabsorption syndromes: such as celiac
disease, cystic fibrosis of the pancreas,
cholestasis.
Anticonvulsant therapy causing increased
metabolism of Vitamin D.

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