10. Vitamin-D deficiency rickets. Flashcards
what is rickets ?
disease where there is defect in chondrocyte differentiation and mineralisation of growth plate and defective osteoid mineralisation caused by vit d deficiency
which in turn also decreases Phosphorus and calcium absorption and retention
2 major groups based on phosphate or calcium levels: phosphopenic and calcipenic. Knowledge of categorization of the type of rickets is essential for prompt diagnosis and proper management
what causes vit d deficiency ?
oral corticosteroids
vit d deficiency or resistance = calcipenic
reduced UV exposure
dark skin
decreased intake of vit d esp the first y’ear through breast milk
400-800IU/day
defective intestinal absorption - cystic fibrosis
chronic pancreatitis leading to decrease in fat soluble vitamins being absorbed
celiac disease
gastrectomy
Liver cirrhosis
drugs - antoconvulsants (phenytoin , carbamepine) increase metabolism of vit d
renal rickets / kidney damage - decrease in active vit d
not deficiency but still calcipenic rickets
end organ resistance to vit d
what are the rare hereditary AR rickets ?
both autosomal recessive disease
Mutation in the 25-hydroxyvitamin-D-1α-hydroxylase gene
Leads to impaired conversion of inactive vitamin D to the active form, 1,25‑dihydroxyvitamin D3 (
Characteri l zed by early onset of rickets, muscle weakness, failure to thrive, hypotonia, and pathological fractures
Vitamin D-dependent rickets type 2
Mutation in the vitamin D receptor gene causes end-organ resistance to vitamin D.
what are the signs and symptoms to hereditary rickets ?
type 1 early onset of rickets muscle weakness failure to thrive hypotonia pathological FRACTURES
type 2
early onset of rickets
failure to thrive
alopecia
what are the symptoms of rickets ?
ONLY IN CHILDREN WHOS GROWTH PLATES HAVE NOT FUSED
bending of long bones
Rachitic rosary: bead-like distention of the bone-cartilage junctions in the ribs
softening of the skull
GENU VARUM! - outward curving of the ipsilateral thigh and inward curving of the ipsilateral leg. Physiologic in pediatric populations until 2 years of age if associated with normal stature, bilateral symmetry, and no clinical symptom
pathological fractures
Harrison groove: depression of the thoracic outlet due to muscle pulling along the costal insertion of the diaphragm
Late closing of fontanelles
dental hypoplasia - delayed tooth eruption
pectus carinatum
swollen in wrist and ankle joints
frontal bossing
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hypocalcemia :
irritability
tetany
muscle weakness
seizures
cardiac - prolonged qt interval
QRS and ST segment mimicking myocardial infraction
chvostek sign
trousseau sign
laryngospasm/bronchospasm
what is the diagnosis of rickets ?
decrease in bone mineral density on x rays
the cortices are thin
growth plates in metaphysic less defined , cupping and stippling and fraying
wide epiphysis
rachitic rosary
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lab
calcipenic
increased alkaline phosphatase
↑ PTH
↓ Calcium (or neutral) and ↓ phosphate (or neutral)
(decrease in calcium levels - increase in parathyroid hormone - targets the bone and MAJORLY the kidneys - calcium and phosphate released from bones / active vit D / calcitriol in kidney - affecting the GIT and PCT and DCT to increase calcium )
↑ Alkaline phosphatase
alkaline phosphatase isoenzyme is elevated as a result of PTH increased osteoblastic activity
Vitamin D-dependent rickets type 1: ↓ calcitriol concentration
normal or high 25-hydroxyvitamin
Vitamin D-dependent rickets type 2: ↑ calcitriol concentration
Low levels of 1,25 dihydroxy vitamin D
serum 25-hydroxyvitamin D (25[OH]D) levels are less than 25 nmol/L (vit produced in the liver but not yet transferred to the kidney calcitriol)
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renal rickets
low calcitriol levels, but 25-hydroxyvitamin D levels may even be normal
most characteristic finding is the elevated phosphate level secondary to poor renal function of chronic kidney diseas
what is the difference between osteomalacia and rickets ?
osteomalacia and rickets are the same however osteomalacia occurs in children and adults while rickets only inchildren.
mineralisation of new osteoid is inadequate
Mineralisation and differentiation of chondrocytes in growth plate is defective
Osteoid mineralisation is low
clinical features in osteomalacia ?
Bone pain and tenderness Pathologic fractures Waddling gait and difficulty walking Myopathy Muscle weakness Spasms Cramps
diagnosis of osteomalacia ?
decreased bone mineral density
thinned cortices
pseudo fractures transverse radiolucency
milkman syndrome
Multiple, almost symmetrical pseudofractures in the cortex of bones
Visible as radiolucent bands
what is the treatment of rickets ?
Even if the mother’s vitamin D level is adequate, infants get a maximum of approximately 40 IU of vitamin D per 750 ml of the breast milk. On the other hand, formula-fed infants receive plentiful amounts of vitamin D because of the fortification of minerals within the milk. Hence, vitamin D deficiency is uncommon in formula-fed infants
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oral high-dose vitamin D:
Ergocalciferol (vitamin D2) or Fultium-D3® (colecalciferol) capsules
Age 1–6 months: 3,000 international units (IU) daily for 8–12 weeks.
75mcg
Age 6 months–12 years: 6,000 IU daily for 8–12 weeks.
150mcg
Age 12–18 years: 10,000 IU daily for 8–12 weeks.
250mcg
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followed by 400 to 600 IU/d in the maintenance phase
this
indicated in infants which are exclusively breastfed
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vit d dependant type 1 rickets
these children will not respond to high doses of cholecalciferol but respond to physiologic doses of calcitriol or 1α-hydroxyvitamin D (1–2 μg daily)
Adequate intake of dietary calcium (30–75 mg/kg per day of elemental calcium)
These children should be monitored for potential side effects of hypercalcemia, hypercalciuria, and nephrocalcinosis secondary to calcitriol therapy. Regular blood work (serum creatinine and calcium, phosphate), urine examination for urine calcium and creatinine ratio, and kidney ultrasound examination should be performed
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VDDR II is a hereditary disease resistant to 1,25-dihydroxyvitamin D, no completely proven treatment is available. most plausible way is to saturate the normal receptors through mega-doses of calcitriol and calcium
mega-doses of calcitriol and calcium
high doses of calcitriol, starting at low dose (0.05 μg/kg per day), which may be increased up to 0.2 μg/kg per day along with calcium and phosphate supplementation. Some patients also may require high-dose i.v. calcium infusion for many months
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renal rickets
Because patients with chronic kidney disease cannot convert the calcidiol into the active form calcitriol, vitamin D supplementation alone is therefore ineffective for renal rickets.
Instead, a low-phosphate diet,
dietary phosphate binders - sevelamer
For Child 6–17 years
2.4g oral powder sachets daily
and oral administration of 1 alfacalcidol / calcitriol is advised, along with maintaining normal 25-hydroxyvitamin D level
how do you supplement calcium ?
currently advised in the BNF for Children are:
Age 1 month – 4 years:
0.25 mmol (10 mg) per kg four times daily, adjusted to response.
Age 5 – 12 years:
0.2 mmol (8 mg) per kg four times daily, adjusted to response.
Age 12–18 years: 10 mmol (400 mg) four times daily, adjusted to response.
