Rickets is the disease of infancy and childhood due to insufficiency of calcium and is clinically characterized by softened and deformed bone
Synthesis of Vitamin D
Etiology
- Vitamin D disorders
- Calcium deficiency
- Phosphorus deficiency
- Renal loss
- Distal Renal tubular acidosis
Vitamin D disorders
- Nutritional Vitamin D deficiency
- Congenital Vitamin D deficiency
- Secondary Vitamin D deficiency
- Malabsorption
- Increase degradation
- Decrease liver 25-hydroxylase
- Vitamin D-dependent rickets Type I
- Vitamin D-dependent rickets type II
- Chronic Renal failure
Calcium deficiency
- Low intake (Diet, Premature infants)
- Malabsorption
Phosphorus deficiency
- Intake of aluminum-containing antacids
Renal Loss
- X linked Hypophosphatemia rickets
- Autosomal dominant Hypophosphatemia rickets
- Hereditary hypophosphatemia rickets with hypercalcemia
Overproduction of phosphatonin
- Tumor-induced rickets
- McCune Albright Syndrome
- Epidermal nevus syndrome
- Neurofibromatosis
Fanconi Syndrome
Dent disease
Pathology of rickets
Histologically, features are seen in osteoid (protein base with/without calcification)
2 Stages:
Active Stage
- The orderly progression of endochondral ossification: Interrupted
- The proliferation of cartilage cells, palisade arrangement, and formation of matrix proceed normally but matrix calcification is the deficit
- Cartilage (noncalcified) column proliferate meanwhile 10-20 times the normal depth of cells ( haphazardly)
- This leads to an enormous accumulation of proliferated cartilage and osteoid tissue resulting in widened, irregular line (epiphyseal), of radiolucency extending deeply into the metaphysis
- Osteoids laid down in both meta-diaphysis, often develops subperiosteally as exuberant growth near the epiphyseal plane ( Rachitic rosary, enlargement of costochondral junction)
- Marrow display: Moderate degree of vascularity and fibrosis
Healing Stages
- Calcium salt deposits in the zone of preparative calcification
- Capillary penetrate the column of proliferative chondrocytes and lay calcified cartilage osteoid
- Osteoid: calcified and transfer to bone
- Osteoid trabeculae atend normal shape
- Fibrotic marrow replaced by fat
Clinical Pictures
Growth restriction
Poor muscle tone
Incomplete fractures
Radiological findings in Rickets
Fraying: Edge of metaphysics loses its sharp border
Cupping: The edge of metaphysis changes from convex to flat or concave shape
Widening distal end of metaphysis
Thickened growth plate
Diaphysis: coarse trabeculae
Generalized rarefaction
Long weight-bearing bone: Bends and thickening on the concave side
In healed phase
A dense line appears at the epiphyseometaphyseal junction: newly calcified cartilages
Epiphyseal lines become narrow and well developed
Frankel line: Sign of healing
The epiphyseal ossified nucleus becomes more dense, large, and well defined
Bending deformity disappears
Lab features of rickets
Treatment Options
Prophylaxis
Administration of Vitamin D
Exposure to sunlight
Especially for premature infants and those an artificial milk feeding
Recommended dietary allowance (RDA)
Calcium
700 mg for children
1000-1200 mg for 50-70 years old females/ all above 70 years
Vitamin D
800 IU for children and elderly
600 IU for all others
Treatment of nutritional rickets
- Stoss therapy: 300000-600000 IU given over 1-5 days
- Alternatively, 2000-6000 IU/ day for 8-12 weeks
Either strategy is followed by a maintenance dose of 400-1000 IU in infants, 600-1000 IU in older children
Given with multivitamins
Supplementary, calcium to all children with 50-70 mg/ day for 6 -12 weeks
Monitoring treatment
- Serum ALP starts normalizing after 3-6 months
- Radiological healing (visible as calcification) 2-4 weeks after
- If an overdose of Vitamin D results in hypercalcemia with urinary calcium deposits
Deformities in the lower leg spontaneously regress, but it fails to regress then osteotomy
Vitamin D Resistance Rickets
- Familial hypophosphatemia rickets
- Renal tubular acidosis
- Vitamin D-dependent rickets
| Vitamin D Resistant Rickets | Vitamin D deficient rickets | |
|---|---|---|
| Etiology | Inherited | Acquired |
| Muscular weakness | Absent | Present |
| Hypocalcemic tetany | Absent | Present |
| Serum Phosphorus | Always low but after treatment never returns to normal but rises | Low/ Normal, if low after treatment returns to normal |
| Growth rate | Seldom becomes normal, the patient remains Dwarf | Normal growth rate resumes |
Vitamin D-dependent Rickets
Renal Osteodystrophy
Renal osteodystrophy is defined as alternation in bone morphology associated with CKD based upon bone biopsy
It is not a single pathology entity
Reflects the disorder pathophysiological status associated with advanced renal disorder
Causes of Renal Osteodystrophy
Failure to synthesize 1,25 dihydroxy Vit D3
25-OH Vit D2–> 1 α hydroxylase/ PCT –>1,25-(OH)2 Vit D3 (Calcitriol)
Vitamin D synthesis
Decrease of Vit D3 => Failure of Intestinal Ca++ absorption=> No bone mineralization =>Osteomalacia
Osteomalacia
Pathology: the thickened layer of an unmineralized matrix (osteoid)
Leaches Calcium from bone
- Subperiosteal bone resorption
- Bowing of digits
Failure to excrete PO4
Hyperphosphatemia
Binds to serum Ca++
Decrease availability to ionized free Ca ++ level
Parathyroid gland
Decrease serum Ca++ in blood
Calcium sensing receptor in PTH
↑ in PTH
Absorbs and leaches calcium from the bone
Osteitis fibrosa cystica
- Holes come from activated osteoclast
- it causes microfracture, bleeding, and granulation of tissue
- Looks brown so-called BROWN TUMOR
Management of Renal Osteodystrophy
Radiological Features of Scurvy
Trummerfield zone: Lucent metaphyseal band
Frankel’s line: Dense zone of provisional calcification
Pelkin’s spur: Metaphyseal spur that results in a cupping of metaphysis
Pelkin’s fracture: Metaphyseal corner fracture
Cortical thinning: Pencil point cortex
Periosteal reaction: Due to subperiosteal hemorrhages
Wimberger’s ring sign: circular opaque radiological shadow surrounding the epiphyseal center of ossification due to bleeding
See also: Osteogenesis Imperfecta
See also: Osteopetrosis
