RICKETS

                          Rickets is defective mineralization or calcification of bones before epiphyseal closure in immature mammals due to deficiency or impaired metabolism of vitamin D, 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.

Signs and symptoms

                                                                   Widening of wrist

                                                          

Signs and symptoms of rickets include:

·         Bone tenderness^[4]

·         Dental problems^[4]

·         Muscle weakness (rickety myopathy)^]

·         Increased tendency for fractures (easily broken bones), especially greenstick fractures

·         Skeletal deformity^[4]

·         Toddlers: Bowed legs and double malleoli (genu varum)^[5]

·         Older children: Knock-knees (genu valgum) or "windswept knees"

·         Cranial deformity (such as skull bossing or delayed fontanelle closure)

·         Pelvic deformity

·         Spinal deformity (such as kyphoscoliosis or lumbar lordosis)

·         Growth disturbance

·         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^[4]

·         Double malleoli sign due to metaphyseal hyperplasia

·         Widening of wrist^[5] raises early suspicion, it is due to metaphyseal cartilage hyperplasia.

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 (Caput Quadratum). 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.

Cause

The primary cause of rickets is a vitamin D deficiency.^[7] 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, portabella and shiitake mushrooms, and oily fishes such as tuna, herring, and salmon. A rare X-linked dominant form exists called vitamin D-resistant rickets or X-linked hypophosphatemia.

Cases have been reported in Britain in recent years^[8] of rickets in children of many social backgrounds caused by insufficient production in the body of vitamin D because the sun's ultraviolet light was not reaching the skin due to use of strong sunblock, too much "covering up" in sunlight, or not getting out into the sun. 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;^[9][10] and people with darker skins need more sunlight to maintain vitamin D levels. The British Medical Journal reported in 2010 that doctors in Newcastle on Tyne saw 20 cases of rickets per year. Rickets had been a significant malaise in London, especially during the Industrial Revolution. Persistent thick fog and heavy industrial smog permeating the city blocked out significant amounts of sunlight so much so that up to 80 percent of children at one time had varying degrees of rickets in one form or the other. Diseases causing soft bones in infants, like hypophosphatasia or hypophosphatemia can also lead to rickets.^[11]

Diagnosis

Wrist X ray showing changes in rickets. Mainly cupping is seen here.

Chest X ray showing changes consistent with rickets. These changes are usually referred to as "rosary beads" of rickets.

Rickets may be diagnosed with the help of:

·         Blood tests:^[19]

·         Serum calcium may show low levels of calcium, serum phosphorus may be low, and serum alkaline phosphatase may be high from bones or changes in the shape or structure of the bones. This can show enlarged limbs and joints.

·         Bone biopsy is rarely performed but will confirm rickets.^[19]

Types

·         Vitamin D-related rickets^[20]

·         Vitamin D deficiency

·         Vitamin D-dependent rickets^[20]

·         Type 1 (25-Hydroxyvitamin D3 1-alpha-hydroxylase deficiency)

·         Type 2 (calcitriol receptor mutation)

·         Hypocalcemia-related rickets

·         Hypocalcemia

·         Chronic renal failure (CKD-BMD)

·         Hypophosphatemia-related rickets

·         Congenital

·         Vitamin D-resistant rickets^[20]

·         Autosomal dominant hypophosphatemic rickets (ADHR)

·         Autosomal recessive hypophosphatemic rickets (ARHR)^[21]

·         Hypophosphatemia (typically secondary to malabsorption)

·         Fanconi's syndrome

·         Seconary to other diseases

·         Tumor-induced osteomalacia

·         McCune-Albright syndrome

·         Epidermal nevus syndrome

·         Dent's disease

 

 

Differential diagnosis

Infants with rickets often have 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.^[22] People with darker skin produce less vitamin D than those with lighter skin, for the same amount of sunlight.^[23]

 

Treatment and prevention

The most common treatment of rickets is the use of Vitamin D.^[24] However, surgery may be required to remove severe bone abnormalities.^[20]

Diet and sunlight

Treatment involves increasing dietary intake of calcium, phosphates and vitamin D. Exposure to ultraviolet B light (most easily obtained 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 people 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.^[25]

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.^[26]

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.^[27]