Rickets is a softening of the bones in a child, sometimes referred to as childhood osteomalacia. It is caused by a decrease in calcium absorption, most commonly due to a decrease in activated vitamin D.
Vitamin D is an essential component of calcium metabolism in the body. Activated vitamin D allows for the absorption of calcium from our diet. Without it, much of the ingested calcium in our diet passes through the intestines without being absorbed and utilized by the body.
The activation of vitamin is a complex reaction that is activated by UV light, in particular UV-B from the sun’s rays. A certain amount of exposure to sunlight is required to generate activated vitamin D everyday. In an adult, it takes approximately 15-20 minutes of direct sunlight on non-protected fair skin to generate approximately 10,000 IU of vitamin D everyday.
In children, however, the amount of time required to activate an appropriate amount of vitamin D is unknown and is difficult to measure. Factors such as age, skin tone, body mass, geographical location and season will all play a role in altering the total. In children, 400 IU of vitamin D are required daily to prevent Rickets and to maintain a healthy level of calcium in the body. It has been shown that children with darker skin pigmentation may require 5-10 times as much sunlight exposure as fair skinned children to activate the daily requirement of vitamin D.
Children aged 3-18 months are at a particularly high risk for the development of rickets, because their bones are growing rapidly at this point in development. High risk groups include children that are strictly breastfed, children with darker skin pigmentation, and children with very limited exposure to sunlight.
In developed countries like the United States, the incidence of Rickets is extremely low (approximately 1 in 200,000 will develop the condition). However, in the developing world, it remains as one of the more common conditions attributable to malnutrition. A lack of vitamin D in the diet is to blame; foods rich in vitamin D include eggs, butter, fish liver oils, fortified milk, and oily fishes such as tuna, herring and salmon.
Symptoms of rickets are due to a lack of calcium, most notably the skeletal deformities that result from the softening of the bones. This includes the classic bow-legged appearance of the tibia and femur, cranial and spinal deformities, and costochondral swelling (swelling along the ribs at their attachment with the cartilage, also known as “rachitic rosary”). Other symptoms include muscle weakness, growth disturbances and failure to grow, dental problems, bone pain, and an increase risk of fractures.
The Indoor Air Quality Act of 1989 reported that Americans spent roughly 93% of their day indoors, which only further compacts the problem of limited sunlight exposure and the development of rickets. Due to the modern lifestyle of developed countries, as well as campaigns to limit sun exposure due to its influence on developing various forms of skin cancer, it is predicted that the incidence of rickets may rise in the future. This has already been observed in Western countries.
Treatment of rickets may be multi-faceted, but includes supplementation with activated vitamin D as the mainstay. Increased exposure to sunlight may be recommended in some cases, though the risk of skin cancer from over-exposure warrants a word of caution. In cases where skeletal deformity has developed, accommodative bracing, orthotics, and other devices may be used.