Rickets

Rickets
Classification and external resources
Radiograph of a two-year old rickets sufferer, with a marked genu varum (bowing of the femurs) and decreased bone opacity, suggesting poor bone mineralization.
ICD-10	E55
ICD-9	268
DiseasesDB	9351
MedlinePlus	000344
eMedicine	ped/2014
MeSH	D012279

Rickets is a softening of bones in children due to deficiency or impaired metabolism of vitamin D, magnesium, phosphorus or calcium, potentially leading to fractures and deformity. Rickets is among the most frequent childhood diseases in many developing countries. The predominant cause is a vitamin D deficiency, but lack of adequate calcium in the diet may also lead to rickets (cases of severe diarrhea and vomiting may be the cause of the deficiency). Although it can occur in adults, the majority of cases occur in children suffering from severe malnutrition, usually resulting from famine or starvation during the early stages of childhood. Osteomalacia is the term used to describe a similar condition occurring in adults, generally due to a deficiency of vitamin D. The origin of the word "rickets" is probably from the Old English dialect word 'wrickken', to twist. The Greek derived word "rachitis" (ραχίτις, meaning "inflammation of the spine") was later adopted as the scientific term for rickets, due chiefly to the words' similarity in sound.

Signs and symptoms

Signs and symptoms of rickets include:

• Bone pain or tenderness
• dental problems
• muscle weakness (rickety myopathy or "floppy baby syndrome" or "slinky baby" (such that the baby is floppy or slinky-like)
• increased tendency for fractures (easily broken bones), especially greenstick fractures
• Skeletal deformity
  • Toddlers: Bowed legs (genu varum)
  • Older children: Knock-knees (genu valgum) or "windswept knees"
  • Cranial, pelvic, and spinal deformities (such as lumbar lordosis)
• Growth disturbance
  
  

  

  Wrist X ray Showing Changes in Rickets, mainly cupping is seen here.
  

  

  Chest X ray showing changes consistent with rickets, this changed is usually referred to as Rosary beads of rickets
• Hypocalcemia (low level of calcium in the blood)
• Tetany (uncontrolled muscle spasms all over the body)
• Craniotabes (soft skull)
• Costochondral swelling (aka "rickety rosary" or "rachitic rosary")
• Harrison's groove
• Double malleoli sign due to metaphyseal hyperplasia
• Widening of wrist raises early suspicion, it is due to metaphysial cartilage hyperplasia.
  

  

  Widening of wrist

An X-ray or radiograph of an advanced sufferer from rickets tends to present in a classic way: bow legs (outward curve of long bone of the legs) and a deformed chest. Changes in the skull also occur causing a distinctive "square headed" appearance. These deformities persist into adult life if not treated. Long-term consequences include permanent bends or disfiguration of the long bones, and a curved back.

Types

• Nutritional Rickets
• Vitamin D Resistant Rickets
• Vitamin D Dependent Rickets
  • Type I
  • Type II
• Congenital Rickets

Cause

The primary cause of rickets is a vitamin D deficiency. Vitamin D is required for proper calcium absorption from the gut. Sunlight, especially ultraviolet light, lets human skin cells convert Vitamin D from an inactive to active state. In the absence of vitamin D, dietary calcium is not properly absorbed, resulting in hypocalcaemia, leading to skeletal and dental deformities and neuromuscular symptoms, e.g. hyperexcitability. Foods that contain vitamin D include butter, eggs, fish liver oils, margarine, fortified milk and juice, and oily fishes such as tuna, herring, and salmon. A rare X-linked dominant form exists called Vitamin D resistant rickets.

Cases have been reported in Britain in recent years of rickets in children of many social backgrounds caused by inability to make vitamin D because the sun's ultraviolet light was not reaching the skin because of persistent use of strong sunblock, or too much "covering up" in sunlight, or spending too much time indoors. Other cases have been reported among the children of some ethnic groups in which mothers avoid exposure to the sun for religious or cultural reasons, leading to a maternal shortage of vitamin D. The British Medical Journal reported in 2010 that doctors in Newcastle on Tyne saw 20 cases of rickets per year.

Diagnosis

Rickets may be diagnosed with the help of:

• Blood tests:
  • Serum calcium may show low levels of calcium, serum phosphorus may be low, and serum alkaline phosphatase may be high.
• Arterial blood gases may reveal metabolic acidosis
• X-rays of affected bones may show loss of calcium from bones or changes in the shape or structure of the bones.
• Bone biopsy is rarely performed but will confirm rickets.

Treatment and prevention

The treatment and prevention of rickets is known as antirachitic.

Diet and sunlight

Cholecalciferol (D₃)

Ergocalciferol (D₂)

Treatment involves increasing dietary intake of calcium, phosphates and vitamin D. Exposure to ultraviolet B light (sunshine when the sun is highest in the sky), cod liver oil, halibut-liver oil, and viosterol are all sources of vitamin D.

A sufficient amount of ultraviolet B light in sunlight each day and adequate supplies of calcium and phosphorus in the diet can prevent rickets. Darker-skinned babies need to be exposed longer to the ultraviolet rays. The replacement of vitamin D has been proven to correct rickets using these methods of ultraviolet light therapy and medicine.

Recommendations are for 400 international units (IU) of vitamin D a day for infants and children. Children who do not get adequate amounts of vitamin D are at increased risk of rickets. Vitamin D is essential for allowing the body to uptake calcium for use in proper bone calcification and maintenance.

Supplementation

Sufficient vitamin D levels can also be achieved through dietary supplementation and/or exposure to sunlight. Vitamin D₃ (cholecalciferol) is the preferred form since it is more readily absorbed than vitamin D₂. Most dermatologists recommend vitamin D supplementation as an alternative to unprotected ultraviolet exposure due to the increased risk of skin cancer associated with sun exposure. Endogenous production with full body exposure to sunlight is approximately 250 µg (10,000 IU) per day.

According to the American Academy of Pediatrics (AAP), all infants, including those who are exclusively breast-fed, may need Vitamin D supplementation until they start drinking at least 17 US fluid ounces (500 ml) of vitamin D-fortified milk or formula a day.

Epidemiology

In developed countries, rickets is a rare disease (incidence of less than 1 in 200,000).

Those at higher risk for developing rickets include:

• Breast-fed infants whose mothers are not exposed to sunlight
• Breast-fed infants who are not exposed to sunlight
• Breast-fed babies who are exposed to little sunlight
• Individuals not consuming milk, such as those who are lactose intolerant

Children ages 6 months to 24 months are at highest risk, because their bones are rapidly growing. Long-term consequences include permanent bends or disfiguration of the long bones, and a curved back.

Mistaken for child abuse

Infants with rickets often suffer bone fractures. This sometimes leads to child abuse allegations. This issue appears to be more common for solely nursing infants of black mothers, in winter in temperate climates, suffering poor nutrition and no vitamin D supplementation. People with darker skin produce less vitamin D than those with lighter skin, for the same amount of sunlight.

See also

• Hypervitaminosis D

References

• Rickets vs. abuse: a national and international epidemic Kathy A. Keller & Patrick D. Barnes Received: 4 November 2007 / Revised: 28 July 2008 / Accepted: 18 August 2008 - Springer-Verlag 2008