Transcript m5zn_b60b358f5b1aca0

Pathogenesis of bioch.changes
vit. D
impaired ca & ph. Absorpt
from intest + ph.reabsorp. By renal
tubules
hypocalcemia +
hypophosphatemia + hyperphosphaturia.
Hypocalcemia
stmulates parathyroid
gl.
Parathormone
mobilisation of
ca from bone to Bl.& thus serum ca is
corrected & to normal. However, Ph.
reabs. by renal tub. is more impaired
exagerated hyperphosphaturia&
hypophosphatemia .
Some exceptions:
1-Serum ca my be :
A-if this physiological hyperparathyrodism
fails to occur .
B- in late stages with depletion of bone ca.
C- during tt of rick. after shock therapy
when deposition of ca & ph in bone occurs
in expense of serum ca.
D- as a complic. For G.E. complicated by
acidosis.
2-serum alkaline phosphatase may be
normal & not in rick. If it is associated
with protein depletion ( atrophic rickets )
Clinical manifestations of early
rickets:
1- Biochemical changes:
Especially high alkaline phosphatase
levels are earliest manifest. of rick.
2- Radilogical changes:
They occur before appearance of
clinical manifest.
3- clinical manifest. :
A- symptoms :
head sweating, irritability, anorexia &
conistipation. Their pathogemesis is not
fully explained but it may result from
disturbed function of autonomic nervous
system.
B- signs:
1-craniotabes: it is a ping pong bone
feeling of skull bones when compressed by
fingers indicating their softness & thinness
it tends to be localised over occipital
& post. part of parietal bones. It is
rarely present before 3 months of age
& disapp. at age of 5-6 ms. up to 1yr.
2- Rossary chest.
Manifestations of advanced
rickets :
*Symptoms:
delayed sitting, standing, walking &
teething or bone deformeties.
*Signs:
1-skeletal manifest.:
1-Head :
1- enlargement & asymmetry.
2- bossing at frontal & parietal eminences
3- some parts of vault of skull may be
menbraneous.
4- box-like appear.of head or caput
quadratum.
5- depression at root of nose.
6-delayed closure of ant. fontanell
7-delayed eruption of teeth .
2- Chest:
1-Rosarry beads: these are small palpable
swellings at costochondral junctions
sparing 1st & 2nd ribs as they are not
2- Harrison’s sulcus:
it is a transverse groove at lower chest wall at
costal insertion of diaphragm produced by
dragging effect of diaph. during resp. movem.
on soft bones of chest .
3- longtudinal sulcus: it is a vertical groove
behind rossary beads resulting from
compression of ribs by atmospheric pressure at
their weakest points.
4- pigeon chest: it is result of protrusion of
sternum.
5- flaring of lower ribs with eversion of
costal margins
Consequences of chest deformities :
1-limitation of chest capacity for expansion
susceptibility to chest infection &
atelactasis.
2- spleen & liver may be palpable due to
downard displacement by deformed thorax
& also due to hypotonicity.
3- Abdomen:
1-abd. Protrusion is nearly a constant
finding in infantile rick.
2- palpable liver & spleen .
3- umblical hernia .
4-Pelvis (Rachitic pelvis ):
1-contracted inlet : due to forward
projection of promontory of sacrum
produced by exageration of lumbar lordosis
2- oultet contraction:due to forward
projection of tip of coccyx.
5-Extremities :
1- enlargement of ends of long bones:
2- pathological fractures .
3- Marfan’s sign
It is a transverse groove felt by palpation at
lower ends of long bones mostly over tibia
just above medial malleolus giving
imperssion of double epiphy.due to abn.
prolif. of cartilage at 2 different areas
producing 2 elevations with a groove in () .
4- Deformities of long bones:it affects upper more than lower limbs
in crawling infants & vice versa in
standing & walking infants.
5- Deformities of joints: due to
hypotonia of ms. & laxity of ligaments
e.g. genu recurvatum, genu varum&
genu valgum.
6- Spine : kyphosis, scolisis &
kyphoscliosis with compensatory
exaggeration of lumbar lordosis are often
present .
II- Muscular manifest.
1: hypotonia: may be due to
hypophosphatemia
III- Neurological manifest.
A-early: in form of sweating, anorexia,
irritability&constipation
b- late: in form of tetany.
D.D. of rickets:
1-Causes of delayed walking:
I- C.N.S. causes :
mental retard., microcephaly, hydrocephalus,
cerebral palsy, post-encephalitic& postmeningetic, post-kernicteric encephalopathy,
cong. Malform., trauma.
II- Spinal cord lesions:Sp.compression, pott’s dis., trauma, spina bifida,
poliomylitis, spinal muscular atrophy dis.,
transverse myelitis.
III- Peripheral n. & myoneural junction
lesions:
Peripheral neuritis, infectious polyneuropathy
IV- Ms. Dis.:
Muscular dystrophy, rickets, cong. hypotonia,
polymyositis, hypokalemia, P.C.M, ch.
Debilitating dis.
V- Bone Dis.:
Osteogenesis imperfecta, chondrodystrophy
2- Causes of craniotabes:
Rickets, hydroceph., cong. $,
osteogenesis imperfecta,
chondrodystrophy, prematurity,
hypervitaminosis A.
3- causes of depressed bridge of nose:
rickets, mongolism, cretinism,
hypertelorism, cong. $., familial, ch.
Hemolytic anemias, hydroceph.
4- causes of rosary chest:
rickets (rounded due to rach. metaph. ) scurvy
(angular due to sublaxation of sternal & costal
parts of ribs), chondrodystrophy, marasmus.
5- causes of delayed closure of ant.
fontanel :
rickets, hydroceph., mongolism, cretinism,
chondrodystrophy, osteogenesis imperfecta,
prematurity, I.C.T.
Complications of rickets
1-Respiratory complic. :
Chest infections with or without atelactasis
are frequent & are due to:
A:chest deformily
expansn
vital
capacity.
B- hypotonia of the resp.ms.with weakness
of the cough reflex.
2- G.I.T.complic.:
A- Alternating diarrh. & conistip. due to
hypotonia of intest. & abd. ms.
B- secondary bact. infection .
3- Others :
A- anemia : due to iron or associated second.
Infection.
B- tetany
C- skeletal deformities.
D- dwarfism.
Treatment of infantile rickets :
I- Prophylactic ttt.: exposure to sun rays,
prophylactic administration of vit. D, administ.
of vit.D to pregnant or lactating mother,
supplmentation by vit.C 25 mg/day ( as vit.C is
acidic.which help solubelity & absorption of ca
II-Curative ttt.:
A- Specific therapy.
Vit.D2 is given in a dose of 1500 – 5000
I.U./day or shock therapy 600000 I.U. once
monthly for 3 successive months .
B- Adjuvant therapy :
Adeqate ca& phosph. Intake, vit. especially vit.
B complex, vit. C & iron , exposure to
ultraviolet sunrays better from 5-8 a.m. & 3-5
p.m.
Non-vit.D deficiency rickets
•Def.: rickets not responding to usual doses of
vit.D.
* Types: primary type ( hypophosphatemic,
hypocalcemic ), renal, hepatic, onchogenic,
associated with anticonvulsant drugs.
Diagnostic aids :
I- History :
age of onset
beyond 2-3 yrs, lack of hist. of
vit.D , hist. of adeq. Vit.D therapy, +ve family
hist., urinary troubles as polyuria, ch.hepatic
troubles as liver failure .
II- Clinical Exam.:
evidence of a renal dis., evidence of a hepatic
dis., hepatosplen. sugg.of metabolic dis. as
fanconi synd., mental retard. + ocular manif.
sugg. of lowe’s synd.
III- Investigations:
serum ca, ph, alkaline phosph., urine for amino
acid, phosphaturia glucosuria, calcuria & PH,
blood for PH, electrolytes, ocular exam. (slit
lamp) for cystine crystals & cataract , renal
function tests, liver function tests.
Vit. D resistant hypophosphatemic rick.
*Etiology : due to inherited disability of kid. To
reabsorp phosphates due to defective
hydroxylation of vit.D. in kid.
*Genetics: sex-linked dominant occuring more
in females.
*Clinical picture: bone deformities especially
in L.L., retarded linear growth, no affection of
general health, no involvement of chest& head
bones, no hypotonia, tetany due to persistent
hypophosphatemia .
*Biochemical changes: hypophosphatemia,
hyperphosphaturia, normal serum ca.
*Treatment: massive vit. D therapy 50000 –
150000 I.U./ day untill healing or toxicity
appears., oral phosphates 0.5- 1.5 gm / d.
during infancy & 1.5-3 gm/day after infancy,
osteotomy for bone defects.
Vit.D resistant hypocalcemic rick.
Etiology: due to inherited inability of renal
tubules to reab. Ca+ ca abs. From intestine
2nd hyperparath.
Genetics : A.R.
Bioch changes : serum ca. , normal
phosphate, aminoaciduria
Ttt: massive vit.D therapy 10000-40000 I.U. /
d., corrected osteotomy for bone defects
Renal rickets
it is either a- renal glomeular rick.
B- renal tubular rick.
Renal glomeular rick (renal osteodystrophy)
Def: alterations in skeletal growth & remodling
that occur in children with chronic renal disease
because of abnormalities in mineral & bone
metabolism.
Etiology : cong. malform. of kid., obestructive
uropathy, ch. pyelonephritis, ch.
glomerulonephritis.
Pathology: inability of kid. to excrete ph
phosphates rexcreted in gut& combine with ca
ca level sec. Hyperparathyrodism
osteodystrophy due to stimul. of osteoclasts
bone resorption.
Diagnosis :rachitic manifest. & dwarfism with
renal sympt. as polyurea, anaemia &
hypertention + manif. of osteoprosis.
Biochemical changes: hyperphosphatemia, ca,
bl. urea & alkaline phosphatase.
ttt : manag. of kid. conditions & correct acidosis,
diet high in ca & low in ph with oral administ.of
Aluminium hydroxide or a cation exchange
resin to remove ph., vit. D 25000-250000
I.U./day, dihydrotachysterol 0.1-0.2 mg/day,
partial excision of parath.gl.
B- Renal tubular rickets :
I- Fanconi syndrome
Def.: synd. Charact. by defect in proximal renal
tubules with reabsorption of glucose, ph, a.a,
Na. K, bicarbonate & uric acid.
Etiology : inherited autosomal recessive,
cystinosis, glycogenosis, lead pois.
Clinical picture:
polyuria, polydepsia, growth retard., uric acid
stones, metabolic acidosis, hypokalemia in form
of ms. weakness, abd. pain & distension, rickets.
Biochemical changes: aminoaciduria, hyper
phospphaturia, glucosuria Na, k, bicarb. uric
acid in urine.
Cong. Hypophosphatasia.:
def.: ch. familial dis. (autoso. Recess.) charact
by inborn dficiency of alkaline phosphatase
Clinical picture:
a- In neonatal period :
soft skeleton, severe deformities, globular
skull,irritability, anorexia, vomiting,
constipation, cyanosis or death.
b- During infancy:
the symptoms appear gradually between 1-6
months. Anorexia, vomiting, constipation,
failure to thrive, bouts of unexplained fever. The
scull shows separation of sutures & wide
bulging ant. Fontanel. Rachitis rosaries &
enlargement of the ends of long bones.
C- during childhood: orthopedic deformities as
genuvalgum, knock knees, defective gait,
marked dental caries& failure to gain weight.
Blood chemistry : serum ph is normal, serum
ca may be normal or increased, alkaline
phosphatase diminished.
ttt. : cortisone may be of value, vit.D has no
therapeutic effect.
Hper vitaminosis D
causes: ingestion of excessive amounts of vit.D:
a- giving therapeutic big doses.
b- increase of the dose by anxious parents
c- substituting a concentrated form of vit.D.
clinical picture: hypotonia, anorexia,
constipation, polyuria, polydipsia, renal failure,
pallor, hypercalcemia & hypercalcuria,
dehydration.
X-ray : metastatic calcification, dense
metaphyseal line associated with decrease of
density of the shaft.
ttt.: discontinue vit.D, low ca diet, correct
dehydration, cortisone, aluminium hydroxide.