Rickets is a vitamin D deficiency disease in children causing disordered bone growth at the epiphyses, with growth retardation, defective mineralization of bone, epiphyseal irregularity on X-ray, and pliability and tendency to fracture of bones. It is common among the malnourished (see malnutrition), especially in cool climates where vitamin D in the skin is minimal. Bones become deformed because inadequate amounts of calcium and phosphate are incorporated into them as they grow. A similarly deficiency of calcium and phosphate in adults results in osteomalacia.
Causes of rickets
The most common cause of rickets is deficiency of vitamin D, which is vital for the absorption of calcium from the intestine into the blood and for its incorporation into bone. Vitamin D is found in fat-containing animal substances, such as oily fish, butter, egg yolk, and liver. There are also small amounts in human and animal milk. Vitamin D is also made in the body through the action of sunlight on the skin.
Rickets occasionally develops as a complication of a digestive disorder that causes malabsorption (failure to absorb nutrients from the intestine). It may also occur in certain rare forms of kidney and liver disease.
Symptoms and signs
The main feature of advanced rickets is deformity of the bones, especially those of the legs and spine. Typically, there is bowing of the legs and, in infants, flattening of the head as a result of softness of the skull. Infants with rickets often sleep poorly and show delay in crawling and walking.
Other features that occur in rickets include kyphoscoliosis (curvature of the spine), a tendency to fractures, and enlargement of the wrists, ankles, and ends of the ribs. There may also be pelvic pain and muscle weakness.