What is rickets?
Rickets is a condition that results in weak or soft bones in children. Symptoms include bowed legs, stunted growth, bone pain, large forehead, and trouble sleeping. Complications may include bone fractures, muscle spasms, an abnormally curved spine, or intellectual disability.
The most common cause is vitamin D deficiency. This can result from eating a diet without enough vitamin D, dark skin, too little sun exposure, exclusive breastfeeding without vitamin D supplementation, celiac disease, and certain genetic conditions. Other factors may include not enough calcium or phosphorus. The underlying mechanism involves insufficient calcification of the growth plate. Diagnosis is generally based on blood tests finding a low calcium, low phosphorus, and a high alkaline phosphatase together with X-rays.
Prevention includes vitamin D supplements for exclusively breastfed babies. Treatment depends on the underlying cause. If due to a lack of vitamin D, treatment is usually with vitamin D and calcium. This generally results in improvements within a few weeks. Bone deformities may also improve over time. Occasionally surgery may be done to fix bone deformities. Genetic forms of the disease typically require specialized treatment.
Rickets occurs relatively commonly in the Middle East, Africa, and Asia. It is generally uncommon in the United States and Europe, except among certain minority groups. It starts in childhood, typically between the ages of 3 and 18 months old. Rates of disease are equal in males and females. Cases of what is believed to have been rickets have been described since the 1st century, and the condition was widespread in the Roman Empire. The disease was common into the 20th century. Early treatments included the use of cod liver oil.
What are the symptoms of rickets?
- pain or tenderness in the bones of the arms, legs, pelvis, or spine
- stunted growth and short stature
- bone fractures
- muscle cramps
- teeth deformities, such as:
- delayed tooth formation
- holes in the enamel
- abscesses
- defects in the tooth structure
- an increased number of cavities
- skeletal deformities, including:
- an oddly shaped skull
- bowlegs, or legs that bow out
- bumps in the ribcage
- a protruding breastbone
- a curved spine
- pelvic deformities
What causes rickets?
Regardless of the type of rickets, the cause is always either due to a deficiency of vitamin D, calcium, or phosphate.
Lack of vitamin D
The body needs vitamin D to absorb calcium from the intestines. The ultraviolet (UV) light in sunlight helps the skin cells convert vitamin D from an inactive to an active state.
If a person does not have enough vitamin D, calcium is not absorbed properly from the food they eat, causing low levels of calcium in the blood.
Low calcium levels result in deformities of bones and teeth, as well as nerve and muscle problems.
Adding vitamin D to a diet is relatively simple. The following foods are rich in vitamin D:
- eggs
- fish oils
- margarine
- some fortified milks and juices
- some oily fishes, including mackerel and salmon
- some soy milk products have vitamin D added
- Vitamin D deficiency can easily be improved with small dietary changes, which makes the most common cause of rickets the most easily avoidable.
There are three common causes of rickets include nutritional rickets, hypophosphatemic rickets, and renal rickets.
Nutritional rickets
Nutritional rickets, also called osteomalacia, is a condition caused by vitamin D deficiency. Vitamin D is a fat-soluble vitamin that is essential for the normal formation of bones and teeth and necessary for the appropriate absorption of calcium and phosphorus from the bowels. It occurs naturally in very small quantities in some foods such as saltwater fish (salmon, sardines, herring, and fish-liver oils). Vitamin D is also naturally synthesized by skin cells in response to sunlight exposure. It is necessary for the appropriate absorption of calcium from the gut.
Infants and children most at risk for developing nutritional rickets include dark-skinned infants, exclusively breastfed infants, and infants who are born to mothers who are vitamin D deficient. In addition, older children who are kept out of direct sunlight or who have vegan diets may also be at risk.
Hypophosphatemic rickets
Hypophosphatemic rickets is caused by chronically low levels of phosphate in the blood. The bones become painfully soft and pliable. This is caused by a genetic dominant X-linked defect in the ability for the kidneys to control the amount of phosphate excreted in the urine. The individual affected is able to absorb phosphate and calcium from the gut, but the phosphate is lost through the kidneys into the urine. This is not caused by a vitamin D deficiency. Patients with hypophosphatemic rickets typically have obvious symptoms by 1 year of age. Treatment is generally through nutritional supplements of phosphate and calcitriol (the activated form of vitamin D).
Renal (kidney) rickets
Similar to hypophosphatemic rickets, renal rickets is caused by a number of kidney disorders. Individuals suffering from kidney disease often have decreased ability to regulate the amounts of electrolytes lost in the urine. This includes calcium and phosphate, and therefore the affected individuals develop symptoms almost identical to severe nutritional rickets. Treatment of the underlying kidney problem and nutritional supplementation are recommended for these patients.
Risk factors
- Poverty: Rickets is more likely to occur among children who are poor because access to adequate nutrition may be limited.
- Poor exposure to sunlight: Children who do not get enough sunlight are more dependent on good nutrition to make sure they are getting enough vitamin D.
- Malnutrition: Rickets is more common in areas of the world where severe droughts and starvation occur.
How To Treat Rickets?
The most common treatment of rickets is the use of vitamin D. However, surgery may be required to remove severe bone abnormalities.
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. 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.
Diagnosis
The diagnosis of rickets is achieved in the following ways:
- Blood tests: These tests measure the levels of calcium and phosphorus. Levels of alkaline phosphatase may also be high.
- Arterial blood gases: This test checks how acidic the blood is.
- X-rays: These may reveal calcium loss in bones, or alterations in the structure or shape of the bones.
- Bone biopsy: This can confirm rickets but is rarely used.
Physical symptoms of rickets, such as bowed legs or a soft skull, will also be checked.
However, these are not reliable enough to use on their own. A positive indication of rickets from one of the above tests is also required for a rickets diagnosis.