Rickets & osteomalaciaSunlight as a source of vitamin D
Adequate supplies of vitamin D3 can be synthesized with sufficient exposure to solar ultraviolet B radiation
Melanin, clothing or sunscreens that absorb UVB will reduce cutaneous production of vitamin D3
Rickets & Osteomalacia
These are different expression of the same disease.
Lack of available calcium and phosphorus ( or both) for mineralization of newly formed osteoid .
Rickets-
Leads to softening of bone & deformity
Osteomalacia- occur in adult
Deficient intake in diet
Renal tubular acidosis
-fibrous or connective tissue tumor
Normal bone growth
1.ZONE OF RESTING CARTILAGE : 1 layer
2.ZONE OF PROLIFERATING CART. : 6 layers
3.zone OF PROVISIONAL CALCIFICATION "epiphyseal line " :
the cart. cells in this layer become mature, they contain alkaline phosphatase release the phosphate in the matrix which already contains ca. & po4 in solution increase production of ca. & po4 precipitation of ca.phosphate in the matrix around the cartilage cells death of the cells.
4.ZONE OF BONE FORMATION :
The layer of prov. calc. is invaded by capillaries and osteoblast which deposit a layer of organic bone matrix "osteoid tis.“ rapidly mineralized and the calcified cartilage ultimately replaced by bone.
PATHOLOGY
The mature cartilage cells will not die and the proliferating zone will be formed of many layers and invades the adjacent zone of of provis. calc.- irregularity of epiphyseal line.
The prov. calc. zone and newly formed ost. tis. will fail to calcify or will calcified irregularly. wide irregular frayed zone of non rigid tis. " RACHITIC METAPHSIS " is produced.
In the shaft the preformed bone is replaced by uncalcified ost. soft rarified cortical bone bone deformities & green stick fractures.
Rickets
Rare before 6 months
Rickets
Rickets
Characteristic feature
Widening of wrist, knee and ankle due to physeal over growth
Rickets
Pelvis - narrow inlet
Growth disturbance
Initial lab. test
Serum Ca, S.Ph, alkaline phosphatase, PTH , 25 Vit-D, 1, 25 Vit-D, creatinine
Rickets
Normal growth rate Growth seldom become N
Serum Ph3 comes N Serum Ph3 never comes
with t/t normal
Rickets
Biochemical finding
Most specific test for vit–D deficiency is 25 vit–D
PTH is under -ve feedback of Calcium
Decrease serum Ca = increase PTH
Alkaline phosphatase increase in all cases of rickets and osteomalacia
Rickets
- vit-D resistant -RTA
- vit-D resistant -RTA
(Liver, Bone, Kidney)
Large quantities of phosphoethanolamine are found in the urine.
Rickets
Bowing of the legs, short stature, and a waddling gait.
Absence of abnormalities of test
3. Blount's syndrome
Osteochondrosis of the tibia resulting in bowing of the legs
May be related to obesity.
Absence of abnormalities of test
Osteomalacia
Pt may present with bone pain, backache and bone tenderness
proximal muscle weakness
Vertebral collapse, kyphosis
Depression
Polyuria
Osteomalacia
Muscles weakness muscle normal
Looser’s zone absent
Bence jones protein
In general the combination of Vit-D, Ca and phosphate
Rickets
Treatment
In general the combination of Vit-D, Ca and phosphate
Orthopedic measure require in very less no. of cases
1 mg of vit-D = 40,000 IU
1 IU = 0.025 microgram
Vit –D 2,000 – 5,000 I.U./day 4- 6 wk
Calcium --- 1g/ day
General nutrition , sunlight ?
Calcium 1 g/ day
Treatment of underling pathology; where appropriat, low fat or gluten free diet
Rickets
Treatment
Or dihydrotachysterol (dose 1/3 of vit D)
Neutral phosphate-1.5- 6 g/ day (4-5 dose)
Calcium – 1 g / day
1, 25 Vit – D 250 IU – 800 IU /day
Calcium 1 g/day
1, 25 Vit – D
Calcium - - 1-3 g / day
i/v Ca with oral
Serum and urinary Ca measurement
Most efficacious method to monitor t/t resolution of Vit –D deficiency
Normal 24 hr urinary Ca excretion = 100 – 250 mg
When serum alkaline Ph3ase Inorganic phosphate
comes normal
Evaluation hazards
increase chance of
Nausea & vomiting
Lack of appetite
Orthopedic measurement
Mild deformity----------brace
If deformity is mark----osteotomy
Vitamin D2 half life <24 hrs
Vitamin D3 half life <21-30 days
WHO SHOULD BE TESTED FOR VITAMIN D DEFICIENCY
HOW DO WE TREAT?