Rickets

lack of vitamin D, calcium, or phosphate, which leads to

softening and weakening of the bones.

Defective mineralization of bone matrix – excessive unmineralised osteoid

Definition:

Vitamin D helps the body properly control calcium and phosphate levels in the body. When the body is deficient in vitamin D, it is unable to properly control calcium and phosphate levels

calcium and phosphorous are found in milk and green vegetables.

Defective Vitamin D metabolism – lowering of calcitriol - intestinal malabsorption of calcium - reduction of serum calcium – Parathyroid stimulation – normalised S.calcium at the expense of

reduced S.Phosphate

Pathophysiology

Parathormone –

Osteoblastic activity -

ALP activity –

Defective Osteoid mineralization

ultraviolet rays 7-Dihydrocholesterol

Cholecalciferol (Vitamin D3)- in dermis

Vit D2 absorbed thru small intestineTransport in serum- binds with X-globulin25-Hydroxylation in Liver1,25- Dihyroxylation in Kidney – active

form

Nutritional Absorptive Renal Others

Aetiology

Decrease in effect & amount of Sunlight Bread/Chapathi rich in Phytate bind

dietary calcium – reduced absorption

Infants who are exclusively breastfed may develop vitamin D deficiency.

Poor Dietary intake of Ca & Vit D Malabsorption disorders – Coeliac d/s,

hepatic osteodystrophy, lactose intolerance

Aetiology

Renal – Renal osteodystrophy, Nephrectomy, renal failure, hypoparathyroidism, X-linked hypophosphatemia/Vit D resistant rickets

Vitamin dependant Type I (Inability to hydroxylate)

Vitamin dependant Type II (Receptor insensitivity)

Anticonvulsant therapy( 25OH in liver)

Failure of deposition of Ca along mature cartilage cell columns

Disorderly invasion of cartilage by blood vessels

Lack of reabsorption at the zone of provisional calcification

Increased thickness of epiphyseal plate

Pathology

Abundant osteoid with Defective mineralization No resorption of uncalcified osteoid by

osteoclasts Normal osteoblast – laid irregularly Abnormal arrangement of collagen bundles

in compact bone

Long bones bent when child starts crawling/walking

Deformities

Valgus deformity

Windswept deformity

Varus deformity

Rachitic rosary

Kyphoscoliosis

Bone pain or tendernessArms Legs Spine Pelvis Skeletal deformities o Bowlegs o pigeon chesto rachitic rosaryo Frontal bossing o Spine deformities (spine curves

abnormally, including scoliosis or kyphosis )

o Pelvic deformities

Symptoms:

Increased tendency toward bone fractures

Dental deformities o Delayed formation of teeth o Defects in the structure of teeth, holes

in the enamel o Increased incidence of cavities in the

teeth ( dental caries ) o Decreased muscle tone (loss of muscle

strength) Muscle cramps Impaired growth Short stature

Acute stage

Normal epiphyseal appearance clouded Metaphyseal splaying Thickened periosteum

Radiology

Epiphysis Mottled & irregular Metaphysis ragged & broader Periosteal thickening disappears

Second stage

Dense shadow Dense line at the end of metaphysis-

deposition of Ca Stage of repair

Third stage

Increase in breadth of metaphysis Clearly defined bone Normal content of Ca salts Bone completely repaired

Fourth Stage

Serum Ca low or normal. o Tetany -prolonged muscle spasm. o Chvostek's sign may be positive (a spasm

of facial muscles occurs when the facial nerve is tapped)

S.Phosphorus may be low. S.ALP may be high. ABG may reveal metabolic acidosis Urinary Ca may be low .

Biochemistry

24-hydroxylase assay – for vitamin D dependency rickets

Serum 25-OH vitamin levels

A bone biopsy is rarely performed but will confirm rickets.

Congenital syphilis Infantile scurvy

D/D

Goals - relieve symptoms and correct the cause of the condition.

Underlying cause must be treated to prevent recurrence.

Treatment:

Medical treatment

Prevention of deformity

Treatment of existing deformity

Dietary sources of vitamin D include fish, liver, milk and cheese.

Exposure to moderate amounts of sunlight is encouraged.

Reduce cereal containing phytates Supplemention of Calcium and

Vitamin D – 3000 i.u./day

Medical Treatment

Before treatment and 2 years after treatment with calcium

Control of movements – reduced pressure upon limbs

(soft bones easily bent by pressure / muscle strain)

Positioning or bracing with ‘rickets’ splints may be used.

Prevention of deformity

Correction by splinting In young children below 4 yrs Useful in lower limbs Continuous supervision needed to prevent

sores

Treatment of established deformity

Correction by osteotomy When deformity is near a joint At least stage 3 in radiograph

Chronic skeletal pain Skeletal deformities Skeletal fractures, may occur without cause

Complications:

Rickets of prematurity Very premature infants at risk Risk factors- hepatobiliary d/s, TPN, Diuretic therapy, chest percussion therapy Pathologic # in NICU Readily heal with treatment

Other types

Antiepileptic medications Induce microsomal P-450 enz Decreased Vit D Should be suspected in neurologic patients

having seizures Start having frequent #

Drug induced

Familial hypophosphatemic rickets X-linked dominant (MC)- Mutn in PEX gene Aut dominant 12p13 – phosphatonins – fgf

23 – cause phosphaturia Aut recessive

Vit D resistant rickets

Renal tubule unable to retain PO4 End organ insensitivity to vit D (AR) Kidney unable to perform 2nd hydroxylation Renal tubular acidosis (kidney excretes

fixed base and wastes bicarbonate) Ca ppt – renal calcinosis

Abnormality

Older age Delayed walking, angular deformities Systemic manifestn – irritability and

apathy minimal Treatment – Oral Phosphorus , Vit D (Compl – nephrocalcinosis) Growth hormone – increased height,

increased PO4, reduced Nephrocalcinosis

C/F

Surgery not efficacious – multilevel osteotomy to correct mechanical axis

Recurrent deformity common Surgery when - gait compromised/severe

pain

Oncogenic hypophosphatemic osteomalacia

Asso with Neurofibromatosis, fibrous dysplasia

Osteoblastoma, hemangiopericytoma of bone, skin tumors

(disrupts renal tubular abs of po4) Secrete phosphatonins Resolve with excision of tumor

Tumor related hypoPO4 rickets

C/C pyelonephritis Congenital Abnormalities Polycystic kidney d/s Secondary hyperparathyroidism Leads to actvn of osteoclast and resorption

of bone (high turn over d/s)

Renal Osteodystrophy

Glomerulus unable to excrete Phosphorus Vit D prodn reduced Ca abs from S.Intestine reduced PTH triggered Increased S.Ca – bone demineralization Precipitate in cornea, skin, blood vessels

C/F similar to Nutritional. Angular deformity, SCFE, AVN Radiography – cuppping of physis not

present Subperiosteal resorption in phalanges,

MC and ulna (feature of Hyperparathyroidism)

Osteosclerosis of skull, rugger jersey spine

Lytic areas in long bones (Brown tumors) Treat underlying d/s- Ca, Vit D, growth

hormone, osteotomy, Ilizarov

Ca Normal or low in all

Phosphate is reduced in all except Renal Osteodystrophy

ALP and PTH high in all

25 OH Vit D N or high in all except nutritional (decreased)

1,25 (OH)2 N or low in all except Vit D dependent typeII (receptor insensitivity)

Maintain an adequate intake of calcium, phosphorus, and vitamin D.

This may require dietary supplements in people who have gastrointestinal or other disorders

Renal causes of vitamin D should be treated promptly.

Prevention:

Levels of calcium and phosphorus should be monitored regularly in people who have renal disorders .

Genetic counseling may help people with a family history of inherited disorders that can cause rickets.