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‫بسم هللا الرحمن الرحيم‬
RICKETS
(‫)الكساح‬
“Defective mineralization of the bone growth
plate (the metaphysis)”.
HISTORY
It has been known since Romans & in the 16th century it
was classically described by Whistler & Glisson.
BASIC SCIENCE BACKGROUNDS
Bone formation is a complex process integrated by
hormonal & growth factors (matrix + mineralization).
At metaphysis: growth is by mineralization of osteoid
tissue & is dependent on adequate calcium (Ca2+),
phosphorus (P) & other elements levels (as magnesium,
copper & fluorine).
At epiphysis & diaphysis: growth is by balance between
bone resorption* & re-formation (remodeling) regulated
by vitamin D, parathyroid hormone* (PTH), growth
hormone (through IGFs), thyroid hormones, insulin,
glucocorticoids* & sex hormones (pubertal).
* Ca2+ & P homeostasis:
Vitamin D (UV irradiation + Dietary), activated by liver (25
OH-Vit.D) then by kidney (1,25[OH]2-Vit.D) by Ca2+or P
in plasma.
Intestinal Ca2+&P absorption
PTH ( Ca2+)
Bone resorption &
serum Ca2+
Distal tubular reabsorption of Ca2+
serum Ca2+
Activate 1-hydroxylase
1,25[OH]2-Vit.D
Renal acid excretion & tubular reabsorption of ( PTH):
-P
phosphaturia & hypopohsphatemia
-Aminoacids
generalized aminoaciduria
PATHOGENISIS
Deficiency of Ca2+ &/or P in plasma
chondrocyte
mineralization at the mataphysis (other elements role?).
plasma Ca2+
PTH
bone resorption & return
of plasma Ca2+ to N + hyperphosphaturia & plasma P.
osteoblastic activity
alkaline phosphatase (ALP).
Metaphyseal growth slows & bone age is retarded.
Trabecular bone demineralization
a greater
proportion of unmineralized osteoid (osteomalacia).
Epiphyseal line is irregular & frayed + new uncalcified
osteoid = rachitic metaphysis +/- cortical bone fractures.
ETIOLOGY
Calciopenic(2ry-PTH):
- vit. D effects ( defects in diet, UV, maternal,
hepatic or renal activation, drugs or its action).
- Malabsorption ( fatty acids, phytates or Ca2+/ P).
Phosphopenic:
- Renal (1ry isolated, hereditary or acquired Fanconi’
syndrome, prox. renal tubular acidosis or oncogenic).
- P deficiency or malabsorption.
Combined:
- Preterm metabolic bone disease (placento intestinal).
PRESENTATION
Clinical picture depends on age & associated disease.
*Age:
-Congenital: usually none but with severe maternal
osteomalacia
neonatal tetany & enamel defects.
-Infantile(< 1yr, +/- preterm): craniotebes (> 4mo), wide
epiphysis (wrists, ankles & costochonderal), boxy &
asymmetrical head, delayed teeth eruption, hypotonia (lax
abdomen & joints), delayed sitting, wide anterior
fontanel, bow-legs, pigeon chest & Harrison groove.
-Toddler:+short, not walking or delayed with deformities.
-Adolescent: Coxa vara, genu valgum, waddling & pain.
PRESENTATION (Cont’d)
*Associated disease:
-Nutritional: protein-calori malnutrition(weight,mid-arm,
s.c.fat, oedema or vit.def.) but if severe, rickets is mild.
-Renal: polyuria, acidosis, growth failure or eye signs.
-Hepatic: jaundice, steatorrhea or cirrhosis.
-Drugs: epilepsy.
-Malabsorption: ch. diarrhea, growth failure or vit.def.
-Vit. D resistance: alopecia or other siblings.
-1ry hypopohsphatemia : affected sisters or mother (XD).
-Preterm: minerals or vit. def.
COMPLICATIONS
Deformities: mild trauma
fractures (greenstick)
& pelvic in girls
difficult labor.
Infection: respiratory.
Tetany(-Ca2+):
-Latent
+ve Chvostek, Trousseau & peroneal
signs.
-Manifest
carpopedal spasms, stridor or generalized
convulsions but in neonates
cyanosis or apnea.
Associated disease: tubular disorder
dehydration
& malabsorption
malnutrition.
INVESTIGATIONS
Chemistery:
- s.ALP, but age interpreted (higher in growth periods).
- s.P(phosphopenic or 2ry PTH), except in renal failure.
-N. s.Ca2+ or low when PTH exhaustion occurs.
- s.25 OH-Vit. D in vit. D deficiency & hepatic disease.
- s.1,25[OH]2Vit.D in renal failure & if s.25OH-Vit.D .
-Aminoaciduria in renal tubular disease & 2ry PTH.
-Glucosuria & aminoaciduria in Fanconi’ syndrome.
X-ray: mineralization, epiphyseal growth & cupping,
fraying & splaying of mataphysis+/-deformity, fracture.
DEFFERNTIAL DIAGNOSIS
Cause of rickets(see above & by response to treatment).
Metaphyseal dysplasia by N. chemistry & no fraying.
Hypophosphatasia by s.ALP & loss of teeth.
Congenital deformities by N. chemistry & x-ray.
TREATMENT
Vit. D deficiency by 1-6x103u. for 4-6 wk then lower
dose judged by response till healing then 400u./d maint.
6x105u. i.m. vit. D (single) for ignorant parents & DD.
Cause treatment, if possible.
Prophylaxis for preterm & maternal osteomalacia baby.
REFERENCES
1. Forfar and Arneil’s textbook of paediatrics (1998).
Campbell AGM & Macintosh N (eds.), 5th edition,
Churchil Livingstone, UK; pp: 301-4, 331, 1057-8,
1194-6, 1866.
2. Nelson textbook of pediatrics (2000). Behrman RE,
Kliegman RM & Jenson HB (eds.), 16th edition,
Saunders, USA; pp: 184-7, 1169, 1207, 1600, 1610-1,
1829, 2133-8.
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