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Vitamin-D deficiency rickets, a disorder that becomes apparent during infancy or childhood, is the result of insufficient amounts of vitamin D in the body. The vitamin deficiency may be caused by poor nutrition, a lack of exposure to the sun, or malabsorption syndromes in which the intestines do not adequately absorb nutrients from foods. Vitamin D is needed for the metabolism of calcium and phosphorus in the body, which, in turn affects how calcium is deposited in the bones; thus it is considered essential for proper bone development and growth. Major symptoms of vitamin D deficiency rickets include bone disease, restlessness, and slow growth. This disorder is rare in the United States but is not uncommon in certain areas of the world.
Symptoms of vitamin D deficiency rickets in infants may be restlessness, lack of sleep, slow growth, a delay in crawling, sitting or walking, thinness of the top and back of the skull (craniotabes), swelling of the skull (bossing), bead-like nodules where the ribs and their cartilages join due to the rapid growth of the arms and the rib cage (rachitic rosary), and a delay in the closing of the skull bone.
Some doctors describe the symptoms of rickets as aches and pains and possible enlarged bones along with swelling at the joints such as wrists and ankles.
If vitamin D deficiency rickets is not treated, the ends of the long bones may become enlarged, the legs may become bowed and knock-knees may result. Muscles can become weak and the chest may become deformed due to the pull of the diaphragm on the ribs that have been weakened by rickets (Harrison's groove). Abnormal development and decay of teeth may also occur.
In more severe, untreated cases of this disorder the bones may become fragile and fractures may easily occur. Convulsions, muscle twitching and sharp bending of the wrist and ankle joints (tetany spasms) may also be present. Occasionally, when there is too little calcium in the blood due to the lack of vitamin D (hypocalcemia), mental retardation may occur.
Vitamin D deficiency rickets can be caused by a lack of vitamin D in the diet, a lack of exposure to the sun, or malabsorption syndromes in which there is an inability of the intestines to adequately absorb nutrients from foods.
Nursing mothers who have a diet deficient in vitamin D may get rickets themselves and pass this condition on to the newborn child.
In areas of the world where cultural habits limit exposure to sun, or the amount of sun in a day or season is limited, Vitamin D deficiency rickets tends to be more prevalent.
Vitamin D deficiency rickets affects males and females in equal numbers. Babies of nursing mothers whose diet is deficient in vitamin D can be affected with this disorder.
Although vitamin D deficiency rickets is rare in the United States, children who are dark skinned and living in cloudy northern cities as well as children on restricted diets due to cultural or religious beliefs are more likely to develop this disorder.
Rickets is more common in regions of Asia where there is a lack of daylight and/or low intake of meat due to a vegetarian diet. Northern Yemen and Kuwait are also areas where Vitamin D deficiency rickets are prevalent due to lack of exposure to the sun because of cultural practices.
Symptoms of the following disorders can be similar to those of vitamin D deficiency rickets. Comparisons may be useful for a differential diagnosis:
Fanconi's syndrome is a rare disorder characterized by kidney dysfunction and bone abnormalities similar to those of vitamin D deficiency rickets. Excess amounts of phosphate, amino acids (usually bicarbonate), glucose, and uric acid are eliminated in the urine. This disorder may be acquired through various causes or inherited as an autosomal recessive or, when associated with Lowe's syndrome, an x-linked recessive genetic trait. Bone symptoms include rickets in children and softening of the bones (osteomalacia) in adults. Fanconi's syndrome may be associated with a variety of inherited metabolic disorders such as cystinosis, Lowe's syndrome, a form of ryrosinemia, hereditary fructose intolerance, Wilson's disease, galactosemia and glycogen storage disorders. (For more information on this disorder choose "Fanconi" as your search term in the Rare Disease Database.)
Infantile scurvy is a disease that is caused by a lack of vitamin C in the diet. Symptoms of this disorder may be anemia, weakness, sores in the mouth, loosening of the teeth, irritability, loss of appetite, failure to gain weight and bleeding under the tissue layer covering the bones. Scurvy is treated with large amounts of vitamin C .
Lowe's syndrome is a rare inherited, metabolic disorder characterized by eye abnormalities such as congenital cataracts and glaucoma, bone malformations caused by vitamin D resistant rickets, mental retardation and impairment of kidney function. This disorder affects only males and is most common in those with fair coloring. Lowe's Syndrome is transmitted through x-linked recessive genes. (For more information on this disorder choose "Lowe" as your search term in the Rare Disease Database.)
Osteomalacia is a disorder characterized by a gradual softening and bending of the bones. Pain may occur in various degrees of severity. Softening occurs because solid bones have failed to form properly (calcify) due to the lack of vitamin D or a kidney dysfunction. This disorder is more common in females than males, and often begins during pregnancy. It can exist alone or in association with other disorders.
Hypophosphatemic rickets is a rare genetic form of rickets characterized by impaired transport of phosphate and diminished vitamin D metabolism in the kidneys. Calcium and phosphate are not absorbed properly in the intestines which can lead to softening of bones. Major symptoms of this disorder include skeletal changes, weakness and slow growth. Cases affecting females are usually less severe than those affecting males. One rare acquired form of this disorder may be associated with a benign tumor. (For more information on this disorder choose "Hypophosphatemic Rickets" as your search term in the Rare Disease Database.)
Pseudovitamin D deficiency rickets (vitamin D dependent rickets, type I) is characterized by more severe skeletal changes and weakness than those of hypophosphatemic rickets. This disorder is caused by abnormal vitamin D metabolism and is inherited as an autosomal recessive trait. This type of rickets often begins earlier than hypophosphatemic rickets. Blood levels of calcium are severely diminished in patients with vitamin D dependent rickets. Amino acids become lost in the urine due to abnormal kidney function. Intermittent muscle cramps may occur. Convulsions and abnormalities of the spine and pelvis may also develop.
In children, the suspected joints are X-rayed and characteristic changes in the bone may be detected. Blood tests to determine the levels of calcium and phosphorus will be undertaken as well. A bone biopsy is performed in difficult cases.
Vitamin D deficiency rickets can be prevented by providing a normal balanced diet to infants and children, assuming that they are exposed to adequate amounts of sun.
Treatment of vitamin D deficiency rickets is accomplished with doses of vitamin D given daily until the bone disease is cured. The dose of vitamin D can then be reduced to the daily recommended requirement.
In more severe cases of vitamin D deficiency rickets when cramps, convulsions, muscle twitching and sharp bending of the ankle and wrist joints (tetany) is present the treatment with vitamin D is supplemented with calcium salts intravenously.
In some instances surgery may be required to correct distortions of bone and muscle.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
For information about clinical trials sponsored by private sources, contact:
The National Institute of Diabetes and Digestive and Kidney Diseases is conducting two clinical trials involving patients with rickets at the Warren G. Magnuson Clinical Center in Bethesda. See above for contact information.
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Report last updated: 2008/04/25 00:00:00 GMT+0