osteomalacia and rickets
DESCRIPTION
By: A.Taskin ( 4th year medical student at Sulaiman Al-rajhee colleges )TRANSCRIPT
OSTEOMALACIA & RICKETS
Abdullah
Taskeen
DIFINATION :
Rickets :
osteopenia with disordered calcification leading to higher proportion of osteoid (unmineralized) tissue prior to epiphyseal closure (in childhood)
osteomalacia :
osteopenia with disordered calcification leading to higher proportion of osteoid (unmineralized) tissue after epiphyseal closure (in adulthood)
BASIC:
Bone consists of :
A- a hard outer shell (cortex) made up of minerals, mainly calcium and phosphorus,
B- a softer inner mesh (matrix) made up of collagen fibres.
WHEN NORMAL BONE IS FORMED :
A - these fibres are coated by mineral (this process is called mineralisation).
B - The strength of the new bone depends on enough mineral covering the collagen matrix.
The more mineral laid down, the stronger the bone.
OSTEOMALACIA HAPPENS : A. if mineralisation doesn’t take place properly.
B. bone is made up of collagen matrix without a mineral covering,
C. so the bones become soft.
D. These softened bones may bend and crack, and this can be very painful.
AGAIN !! DIFINATION :
Rickets :
osteopenia with disordered calcification leading to higher proportion of osteoid (unmineralized) tissue prior to epiphyseal closure (in childhood)
osteomalacia :
osteopenia with disordered calcification leading to higher proportion of osteoid (unmineralized) tissue after epiphyseal closure (in adulthood)
ETIOLOGY AND PATHOPHYSIOLOGY
A. Vitamin D Deficiency
B. Mineralization Defect
C. Phosphate Deficiency
CLINICAL PRESENTATION :
INVESTIGATION :
OTHERS :
Serum 25OHD = low ( exept in V. D resistance rickets )
Serum fibroblast FGF-23 = elevated in tumor associated osteomalcia
RADIOLOGIC FINDINGS - pseudofractures,
‘Looser’s zones’
- Linear areas of low density surrounded by sclerotic
borders.
- loss of radiologic distinctness of vertebral bod trabecula,
- concavity of the vertebral bodies
- narrow radiolucent lines (healed stress fractures )
Looser Zones
Looser Zones
diffuse osteopenia and several insufficiency stress fractures of the bilateral ribs (arrows) and scapulae
Stress fracture
several insufficiency stress fractures in the right femoral lesser trochanter, both femoral necks (arrows), acetabula (arrowhead), and pubic rami (white arrow).
Stress fracture
GOLD STANDARD Bone biopsy :
A. Increased osteoid width (> 15 μm),
B. increased mineralization lag time, and
C. lack of Uptake of double tetracycline labelling in osteoid seams.
ostoid ( pink ) > 80 % Ostoid thickness > 12 um
Mineralization lag time > 100 days
RX: - depends on the underlying cause
• vitamin D supplementation • PO4 supplements if low serum PO4 is present
• Ca supplements for isolated calcium deficiency
• bicarbonate if chronic acidosis
RX :
calcitriol or alfacalcidol
there is defective 1α-hydroxylation,
e.g. chronic kidney disease, vitamin D dependency and hypophosphataemic rickets with osteomalacia.
REFERENCES :
Kummar & clarck 7th edition
MD- consult
Good bye !!