rickets

RICKETS

Rickets is a childhood disorder involving softening and weakening of the bones.

It is primarily caused by lack of vitamin D, calcium, or phosphate.

Vitamin D is a fat-soluble vitamin that may be absorbed from the intestines or may be produced by the skin when the skin is exposed to sunlight (ultraviolet light of sunlight helps the body to form vitamin D).

The absorbed vitamin D is converted into its active form to act as a hormone to regulate calcium absorption from the intestine and to regulate levels of calcium and phosphate in the bones.

If there is a deficiency of Vitamin D, the body is unable to properly regulate calcium and phosphate levels. When the blood levels of these minerals become too low, it results in destruction of the support matrix of the bones.

In rickets, another mechanism in the body works to increase the blood calcium level. The parathyroid gland may increase its functioning rate to compensate for decreased levels of calcium in the bloodstream.

To increase the level of calcium in the blood the hormone destroys the calcium present in the bones of the body and this results in further loss of calcium and phosphorous from the bones. In severe cases, cysts may develop in the bones.

Environmental conditions where sunlight exposure is limited like indoor confinement or working indoors during daylight hours may reduce source of vitamin D;

Inadequate daily consumption - a lack of vitamin D in the diet, a dietary lack of calcium and phosphorous may also play a part in nutritional causes of rickets, have trouble digesting milk products, people who are lactose intolerant;

Liver Failure; Dark Pigmentation

. Fast growth, increased requirement (relative deficiency)

. Diseases and drug: Liver diseases, renal diseases Gastrointestinal diseases Antiepileptic Glucocorticosteroid.Malabsorption-Steatorrhoea

Cholecalciferol (vitamin D-3) is formed in the skin from 7-dehydrotachysterol. This steroid undergoes hydroxylation in

2 steps.

Pathophysiology - Metabolism of vitamin D

• The first hydroxylation occurs at position 25 in the liver, producing calcidiol (25-hydroxycholecalciferol), which circulates in the plasma as the most abundant of the vitamin D metabolites and is thought to be a good indicator of overall vitamin D status.

Cholecalciferol (vitamin D-3) is formed in the skin from 7-dihydrotachysterol. This steroid undergoes hydroxylation in 2

steps.

Pathophysiology

• The second hydroxylation step occurs in the kidney at the 1 position, where it undergoes hydroxylation to the active metabolite calcitriol (1,25-dihydroxycholecalciferol - DHC). This cholecalciferol is not a vitamin, but a hormone.

Calcitriol acts on regulation of calcium metabolism:

Calcitriol promotes absorption of calcium and phosphorus from the intestine,

increases reabsorption of phosphate in the kidney, acts on bone to release calcium and phosphate; Calcitriol may also directly facilitate calcification.

Calcitriol (1,25-DHC) – acts as a hormone rather than a vitamin, endocrine and paracrine properties

• These actions increase the concentrations of calcium and phosphorus in extracellular fluid.

• The increase of Ca and P in extracellular fluid, in turn, leads to the calcification of osteoid, primarily at the metaphyseal growing ends of bones but also throughout all osteoid in the skeleton.

• Parathyroid hormone facilitates the 1-hydro-xylation step in vitamin D metabolism

In the vitamin D deficiency state, hypocalciemia develops, which stimulates excess parathyroid hormone, which stimulates renal phosphorus loss, further reducing deposition of calcium in the bone.

Excess parathyroid hormone also produces changes in the bone similar to those occurring in hyperparathyroidism.

Early in the course of rickets, the calcium concentration in the serum decreases.

After the parathyroid response, the calcium concentration usually returns to the reference range, though phosphorus levels remain low.

Alkaline phosphatase, which is produced by overactive osteoblast cells, leaks to the extracellular fluids so that its concentration rises to anywhere from moderate elevation to very high levels.

The history in patients with rickets may include the following:

The infant's gestational age, diet and degree of sunlight exposure should be noted.

A detailed dietary history should include specifics of

vitamin D and calcium intake.

A family history of short stature, orthopedic abnormalities, poor dentition, alopecia, parental consanguinity may signify inherited rickets.

Evaluation

Rickets is a systemic disease with

skeletons involved most, but the

nervous system, muscular system

and other system are also

involved.

Generalized muscular hypotonia is observed in the most patients with clinical signs of rickets.

Craniotabes manifests early in infants, although this feature may be normal in infants, especially for those born prematurely.

Clinical signs

• If rickets occurs at a later age, thickening of the skull develops. This produces frontal bossing and delays the closure of the anterior fontanelle.

Frontal bossing

• Skeletal deformities including Bow legs, Forward projection of the breastbone - pigeon chest or pectus carinatum),Funnel chest(pectus excavatum), "Bumps" in the rib cage (rachitic rosary) and asymmetrical or odd-shaped skull;

Chest deformity

Funnel chest – pectus excavatum

Pigeon chest

Clinical signs

In the chest, knobby deformities results in the rachitic rosary along the costochondral junctions. The weakened ribs pulled by muscles also produce flaring over the diaphragm, which is known as Harrison sulcus. The sternum may be pulled into a pigeon-chest deformity.

Rib beading (rachitic rosary)

Pathway of Vitamin D Production

Knock knee deformity (genu valgum)

Bowleg deformity (genu varum)

The ends of the long bones demonstrate that same knobby thickening. At the ankle, palpation of the tibial

Clinical signs

malleolus gives the impression of a double epiphysis (Marfan sign).

Increased tendency toward bone fractures. Because the softened long bones may bend, they may fracture one side of the cortex (greenstick fracture).

In the long bones, laying down of uncalcified osteoid at the metaphyses leads to spreading of those areas, producing knobby deformity (cupping and fraying of the metaphyses).

Spine deformities (spine curves abnormally, including scoliosis or kyphosis). In more severe instances in children older than 2 years, vertebral softening leads to kyphoscoliosis

Pain in the bones of Arms, Legs, Spine, Pelvis. Dental deformities Delayed formation of teeth Defects in the structure of teeth Holes in the enamel Increased incidence of cavities in the teeth (dental caries)

Progressive weakness Decreased muscle tone (loss of muscle

strength) Muscle cramps Impaired growth Short stature (adults less than 5 feet tall)

Clinical signs

In children with rickets, complete physical and dental examinations should be performed. The entire skeletal system must be palpated to search for tenderness and bony abnormalities. Rickets should be suspected in older bowlegged children and in cases associated with asymmetry, pain, or progression in severity. a

Physical examination

.Gait disturbances and neurologic abnormalities (such as hyperreflexia) in all children should be

sought.. The review of systems should focus on growth and

orthopedic concerns and signs and symptoms of hypocalcemia, such as muscle cramps, numbness,

paresthesias, tetany and seizures.

Laboratory findings

Laboratory investigation may include: serum levels of calcium (total and ionized with

serum albumin), phosphorus, alkaline phosphatase (ALP) parathyroid hormone, calcidiol urine studies include urinalysis and levels of

urinary calcium and phosphorus.

Decrease

in serum calcium, serum phosphorus, calcidiol, calcitriol, urinary calcium.

The most common laboratory findings in nutritional rickets are:

Parathyroid hormone, alkaline phosphatase,

urinary phosphorus levels are elevated.

Early on in the course of rickets, the calcium (ionized fraction) is low; however it is often within the reference range at the time of diagnosis as parathyroid hormone levels increase.

Calcidiol (25-hydroxy vitamin D) levels are low, and parathyroid hormone levels are elevated; however, determining calcidiol and parathyroid hormone levels is typically not necessary.

Calcitriol levels may be normal or elevated because of increased parathyroid activity.

The phosphorus level is invariably low for age. Alkaline phospohatase levels are elevated. A generalized aminoaciduria occurs from the parathyroid

activity; aminoaciduria does not occur in familial hypophosphatemia rickets (FHR).

Laboratory Studies

Classic radiographic findings include:

widening of the distal epiphysis,

fraying and cupping of the metaphysis, and angular deformities of the arm and leg bones.

Classic radiographic findings include

Anteroposterior and lateral radiographs of the wrist of an 8-year-old boy with rickets demonstrates cupping and fraying of the

metaphyseal region

Rickets in wrist - uncalcified lower ends of bones are porous, ragged, and saucer-shaped

(A) Rickets in 3 month old infant

(B) Healing after 28 days of treatment

(C) After 41 days of treatment

A

B C

Radiographic image of wrist and forearm showing pathologic fractures of radius and ulna with rachitic changes of distal end of radius and ulna.

X-ray in rickets

Early stage Usually begin at 3 months old Symptoms: mental psychiatric symptoms Irritability, sleeplessness Signs: occipital bald Laboratory findings: Serum Ca, P normal

or decreased slightly, ALP normal or

elevated slightly, 25(OH)D3 decreased X-ray changes: normal or slightly

changed

Advanced stage On the basis of early rickets, osseous

changes become marked and motor development becomes delayed.

1. Osseous changes:1) Head: craniotabes, frontal bossing,

boxlike appearance of skull, delayed closure of anterior fontanelle

2) Teeth: delayed dentition with abnormal order, defects

3) Chest: rachitic rosary, Harrison’s groove, pigeon chest, funnel-shaped chest, flaring of ribs

4) Spinal column: scoliosis, kyphosis, lordosis

5) Extremities: bowlegs, knock knee, greenstick fracture

6) Rachitic dwarfism

2. Muscular system: potbelly, late in standing and walking

3. Motor development: delayed

4. Other nervous and mental symptoms

Laboratory findings: Serum Ca and P decreased ALP elevated

X-ray changes: Wrist is the best site for watching the

changesWidening of the epiphyseal cartilageBlurring of the cup-shape metaphyses of

long bone

Healing stage: Symptoms and signs of Rickets alleviate or

disappear by use of appropriate treatment. The blood investigations become normal, except

ALP, that may be slightly elevated.

Sequelae stage: All the clinical symptoms and signs disappear. Blood investigations and X-ray changes are

recovered, but osseous deformities may be left. Usually seen in children after 3 years old.

I Mild form: small changes of nervous system, changes of one part of the skeleton;

II Moderate form: changes of all organs and systems, changes of two parts of the skeleton;

III Severe form: damaging function of all organs and systems, changes of three parts of the skeleton;

Classification

Types of Rickets

Nutritional

Nutritional rickets results from inadequate sunlight exposure or inadequate intake of dietary vitamin D, calcium, or phosphorus.

Vitamin D dependent

Vitamin D-dependent rickets, type I is secondary to a defect in the gene that codes for the production of renal 25(OH)D3-1-alpha-hydroxylase.

Vitamin D-dependent rickets, type II is a rare autosomal disorder caused by mutations in the vitamin D receptor. Type II does not respond to vitamin D treatment; elevated levels of circulating calcitriol differentiate this type from type I.

Vitamin D resistant

Rickets refractory to vitamin D treatment may be caused by the most common heritable form, known as vitamin D-resistant rickets or familial hypophosphatemic rickets.

Because of mutations of the phosphate-regulating gene

on the X chromosome, renal wasting of phosphorus at the proximal tubule level results in hypophosphatemia. Normal levels of calcitriol are found in this disorder.

Other Conditions That Can Cause Rickets Medications

Antacids Anticonvulsants Corticosteroids Loop diuretics

Malignancy Prematurity Diseases of organs associated with vitamin D and calcium

metabolism Kidney disease Liver and biliary tract disease

Malabsorption syndromes Celiac disease Cystic fibrosis (rare)

Assessed according to the followings:

1. History 2. Physical examination 3. Laboratory findings 4. X-ray changes

The replacement of Vitamin D may correct rickets using these methods of ultraviolet light and medicine. Rickets heals promptly with 4000 IU of oral vitamin D per day administered for approximately one month.

Parents are instructed to take their infants outdoors for approximately 20 minutes per day with their faces exposed. Children should also be encouraged to play outside.

Foods that are good sources of vitamin D include cod liver oil, egg yolks, butter and oily fish. Some foods, including milk and breakfast cereals, are also fortified with synthetic vitamin D.

1. Special therapy: Vitamin D therapy

A. General method: Vitamin D 2000-4000 IU/day

for 2-4 weeks, then change to

preventive dosage – 400 IU.

B. A single large dose: For severe case, or Rickets with complication, or those who can’t bear oral therapy.

Vitamin D3 200000 – 300000 IU, im,

preventive dosage will be used after 2-3 months.

4. Calcium supplementation: Dosage: 1-3 g/day

only used for special cases, such as baby fed mainly with cereal or infants under 3 months of age and those who have already developed tetany.

5. Plastic surgery: In children with bone deformities after 4

years old plastic surgery may be useful.

Splints-for correction of deformities

Corrective osteotomy

1. Pay much attention to the health care of pregnant and lactating women, instruct them to take adequate amount of vitamin D.

2. Advocate sunbathing3. Advocate breast feeding, give

supplementary food on time

Vitamin D supplementation: In prematures, twins and weak babies,

give Vitamin D 800IU per day, For term babies and infants the

demand of Vitamin D is 400IU per day, For those babies who can’t maintain a

daily supplementation, inject muscularly

Vitamin D3 100000-200000 IU.