1. Rickets of Vitamin D deficiency

2. Definition
Rickets is the term signifying a failure in mineralization of growing bone or osteoid tissue.
Failure of mature bone to mineralize is called osteomalacia.

3. I. Vitamin D 1.The form of vitamin D and its conversion in human body
1) Two forms of vitamin D
Vitamin D2 (ergocalciferol)
Vitamin D3 (cholecalciferol)
ultraviolet rays
7-dehydrocholesterol cholecalciferol
ergosterol
ergocalciferol

4. Content of VitD3 in animal food
breast milk　　 µg /L
cow's milk 　 ~1µg /L
egg　 　　 µg /100g
butter　 ~1.5µg /100g
Vit D 1 µg = 40IU

5. 2)The conversion of vitamin D V D2 , V D3 liver
25(OH)D ( 25-OH-cholecalciferol)
1,25(OH)2D (1,25-dihydroxycholecalciferol )
Renal cortical cells
25-OHD (main form in blood)
　　 1, 25-(OH)2D (high activity)

6. 2.Functions of 1,25(OH)2D3
1) Facilitation of intestinal absorption of calcium and phosphorus (promote intestinal mucosa synthesis a special CaBP)
2) Increasing reabsorption of phosphorus through proximal convoluted tubule in the kidneys

7. 3) Promote normal bone formation and mineralization
3) Promote normal bone formation and mineralization. (deposition and reabsorption)
4) In conjunction with parathormone (PTH) and calcitonin (CT), it has a major role in homeostasis of calcium and phosphorus in the body's fluids and tissues.

8. 3.Functions of PTH
1) Facilitation of intestinal absorption of calcium and phosphorus
2) Increasing reabsorption of calcium , suppressing reabsorption of phosphorus in the kidneys
3) Promote decalcification of bone , blood calcium is increased ; cannot promote normal bone formation

9. Vitamin D Metabolism & Mineral Homeostasis
VitD2
UVL
VitD3
7-DHCC
25-hydroxylase
25-OHD
PTH
1,25 (OH)2D
1-hydroxylase Ca P

10. Ⅱ. Etiology
1. Inadequate direct exposure to ultraviolet rays in sunlight
2. Inadequate intake of vitamin D
3. Rapid growth, such as in low-birth weight infants , premature infants and in adolescents.
* Vit D 1 µg = 40IU

11. 4. Deficient absorption, conversion and activation
of vitamin D
5. Anticonvulsant therapy
Glucocorticoids appear to be antagonistic to
vitamin D in calcium transport.

12. Ⅲ. Mechanism Vitamin D deficiency Ca absorption from intestines
Serum Ca
PTH
P reabsorption in kidney
Serum P
mobilization of calcium from bone
Serum Ca normal or slightly
Level of Ca , P
Failure of mineralization of bone
rickets

13. Ⅳ. Pathology Failure of mineralization of bone
Osteoblast proliferation
Over osteoid tissue accumulated
Epiphyseal enlargement
Cortical bone resorbed and replaced by osteoid tissue
Rachitic rosary Bangle or anklet-like sign
Shaft lose its rigidity ,
easily deformed or fractured by stress
Skeletal deformities (bowleg, knock knees)

14. 骨骺osteoepiphysis 骨样组织 osteoid tissue
骨化中心center of ossification
骨骺软骨epiphyseal cartilage
临时钙化带 zone of provisional calcification
骨干diaphysis 干骺端metaphysis

15. Normal
Rickets

16. Ⅴ.Clinical manifestation
Early stage
Symptoms:
Irritation ,increased crying, excessive sweating,
abnormal sleeping with over awakening
Signs: bone deformities are rare at this stage
alopecia

17. Ⅴ.Clinical manifestation
Early stage
Laboratory examination (Serum):
calcium normal or (2.25~2.74mmol/L)
phosphorus (0.97~1.61mmol/L)
1,25(OH)2D3
alkaline phosphatase (AKP)

18. X-rays:
X-rays is normal or epiphyseal calcification is not clear as usual
a X-ray of wrist is the best for diagnosis since characteristic change of the ulna and radius occurs in rickets

19. Advanced stage
Symptoms : Symptoms are more evident
bone deformities:
head: craniotabes

20. caput quadratum

21. Teeth: Eruption of the deciduous teeth may be delayed, and there may be defects of the enamel and extensive caries.
spinal column: slight to moderate degree of lateral curvature
extremities: Bangle or anklet-like sign
bending leg (bowlegs, knock knees)

22. Bangle or anklet-like sign

23. bowlegs knock knees

24. chest:
the beading of the ribs
pigeon breast deformity
Harrison groove

25. pigeon breast deformity funnel chest

26. pigeon breast deformity and Harrison groove
bowlegs knock knees

27. laboratory examination (Serum):
calcium (2.25~2.74nmol/L)
phosphorus (0.97~1.61nmol)
1,25(OH)2D3
AKP

28. normal
rickets
x-rays

29. Healing stage Symptom: If sufficient vitamin D is given, symptom will
be milder or disappear within a few days
Deformities:
The repair of deformities may take a few
months or even a few years, and in some
cases complete repair may be impossible.

30. Laboratory examination:
Serum Ca and P return to normal range
AKP will decrease to normal within 4~6W
X-ray: preparatory calcification reappears 2W later

31. preparatory calcification reappears

32. Sequelae stage symptom disappear sequelaes may exist in some cases
Laboratory examination and X-ray are normal

33. Ⅵ. Diagnosis The diagnosis should be based on :
History of inadequate intake of vitamin D
Clinical manifestations
Characteristic change of X-ray
Abnormal serum Ca, P and AKP
25(OH)D3 is the most reliable standard to diagnose, but this test can not be done in many hospitals.

34. Ⅶ. Differential diagnosis
Congenital thyroid hormone deficiency
Achondroplasia
Other rickets
vitamin D dependant rickets
Familial hypophosphatemia
renal or hepatic rickets
Distal renal tubular acidosis

35. Ⅷ. Treatment Oral administration of vitamin D 2000~4000IU/day
or 1,25(OH)2D3,0.5~2.0ug/day for a month, after
about 1 mo of therapy, the dose can be reduced
gradually to the usual maintenance level of 10 µg
(400 IU)/day.
Muscular injection of vitamin D ~300000IU,
then oral vitamin D 400IU/day 3 month later.

36. In Healing stage
Oral administration of vitamin D 400~800IU/day

37. Ⅸ.Prognosis
If sufficient amounts of vitamin D are administered, healing begins within a few days and progresses slowly until the normal bony structure is restored.
Rickets in itself is not a fatal disease, but complications and intercurrent infections such as pneumonia, tuberculosis, and enteritis are more likely to cause death of rachitic children than normal children.

38. Ⅹ. Prevention
Rickets can be prevented by exposure to ultraviolet light or by oral administration of vitamin D.
The daily requirement of vitamin D is 400IU.
Premature infants, LBW, Twins or polyembryony---1week after birth, 800 IU/d. after 3 months, 400 IU/d, until 2 years.
Full-term infant---2weeks after birth, 400IU/d, until 2years.

39. Ⅹ. Prevention
Vitamin D should also be administered to pregnant and lactating mothers.
Oral administration of vitamin D is not emphasized in children over 2 years old
Usually, calcium should not be given unless insufficient milk or poor nutrition.