A softening of bones in children due to deficiency or impaired metabolism of vitamin D, phosphorus or calcium,
Can lead to fractures and deformity of the bones.
In developed countries, rickets is a rare disease with an incidence of less than 1 in 200,000.
Considered an historical disease, but persists in United States in in supplemented, exclusively breast fed infants.
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.
Rickets is the result of abnormal mineralization of bone and cartilage in growing children.
Similar condition in adults whose epiphyseal plates have closed is osteomalacia.
Clinical features of rickets include: apathy, listlessness, poor growth, muscle cramps, weakness, hypotonia, numbness, paresthesias, tetany, seizures, pot belly, waddling gait, soft, misshapen head with widened sutures and frontal bossing, delay in eruption of teeth, rachitic rosary, Harrison’s groove, which is an indentation at point of insertion of diaphragm, due to the pull of the diaphragm against the softened lower ribs, bowing of limbs and swollen joints.
Radiographic findings include: epiphyses appear widened and flared with irregular epiphyseal-metaphyseal junctions, involvement of the costochondral junctions with rows of beadlike prominences, the “rachitic rosary”, long bones appear bowed with saber shapes, pseudofractures are often found on the concave side of femoral neck, pubic rami, ribs, clavicles, and lateral aspect of scapulae.
Besides skeletal effects, hypovitaminosis D associated with infectious, metabolic,, neoplastic, and immune disorders.
Normal phosphorus and parathyroid hormone levels make diagnosis unlikely.
Calcium, total and ionized may be normal in rickets
Alkaline phosphatase is markedly elevated.
Urinary calcium level is usually decreased in rickets.
Calcitriol level is usual normal.
Most common cause is a deficiency of vitamin D.
Vitamin D is necessary to produce concentrations of calcium and phosphate adequate for proper bone mineralization.
May also be caused by medications that alter absorption or secretion of phosphate and calcium, including antacids, anticonvulsants, corticosteroids, and loop diuretics.
Disease states, such as Crohn’s disease, pancreatic disease, biliary disease, gastrointestinal loops and fistulae, cirrhosis, chronic renal disease, and mesenchymal tumors, may also alter absorption and metabolism of these ions.
The prevalence of vitamin D deficiency among infants may be as high as 43-70%, depending on the definition of vitamin D deficiency and the latitude of the population being studied.
Consuming adequate quantities of vitamin D is difficult, and requires a diet fortified with Vitamin D or vitamin supplements.
Current recommendations for daily intake are 400 IU per day for all infants, children, and adolescents.
Average daily intake by adults from fish, eggs, and butter or margarine is only 50 to 100 IU.
Infants born to vitamin-D replete women have an 8- to 12-week store of vitamin D at birth.
No UV light exposure is recommended during the first six months of life, therefore infants are expected to rely entirely on dietary sources of vitamin D.
Breast feeding does not ensure the baby is getting adequate amounts of vitamin D.
Infant formula must be fortified with 40-100 international units vitamin D 100 kcal, which corresponds to 270-677 international units per liter.
Breast milk contains 20-80 international units of vitamin D per liter which is much less than an infant formula.
Breast milk from vitamin D-replete women has a vitamin D concentration of only 25 IU per liter, much below the recommended daily intake of 400 IU.
Cholecalciferol, vitamin D3, is the major vitamin D metabolite the crosses from maternal serum into breastmilk.
That downstream metabolites of vitamin D in human milk is negligible.
Single or daily doses of cholecalciferol supplementation of mothers provides breastmilk concentrations that result in vitamin D sufficiency in breast-fed infants (Oberhelman SS et al ).
Calcium malabsorption occurs due to inadequate vitamin D levels, and hypocalcemia may result from inadequate intake of calcium or from vitamin D-dependent metabolic disorders, of which there are 2 types.
Type I, sometimes known as pseudo-vitamin D-deficiency rickets, is due to defective production of 25(OH)D3-1-α-hydroxylase, an enzyme necessary for the conversion of calcidiol to calcitriol in the kidneys.
Type II, also called hereditary rickets, is rare, and is caused by mutations in vitamin D receptors and the inability of the ligand to bind or stimulate the proper physiologic response.
Type II hereditary rickets may be associated with high levels of calcitriol.
Vitamin D-resistant rickets, or familial hypophosphatemic rickets, refers to a clinical presentation of rickets that is caused by a hereditary renal wasting of phosphorus at the proximal tubule level.
Vitamin D-resistant rickets, or familial hypophosphatemic rickets laboratory evaluation associated with low phosphate levels, normal calcitriol levels, and hypercalciuria.
Vitamin D-resistant rickets is associated with a family history of short stature, bone abnormalities, poor dentition, alopecia, or parental consanguinity.
Other etiologies for hypophosphatemia include inadequate nutritional intake, X-linked hypophosphatemia, renal tubular acidosis, Fanconi syndrome, and Dent disease, may also lead to rickets.
Vitamin D deficiency may be treated anywhere along the metabolic pathway.
Vitamin D1, the substance in the skin that responds to sunlight, is given as 60,000 IU once, then 6000 IU daily until the rickets is clinically resolved.
Vitamin D2, ergocalciferol, may be given as 1000 to 5000 IU daily for 6 to 12 weeks.
Vitamin D3, cholecalciferol, is typically administered as either 5000 to 10,000 IU daily for 2 to 3 months, or as 600,000 IU in 1 day, divided into 4 to 6 doses.
Vitamin D is not effective in treatment of familial hypophosphatemic rickets, Type II vitamin D-dependent rickets, or disorders of phosphate metabolism.
During treatment monitoring of serum calcium and alkaline phosphatase, calcium, magnesium, phosphate, alkaline phosphatase, calcidiol, parathyroid hormone at monthly intervals, and a wrist x-ray at 3 months to ensure effective management.
The American Academy of Pediatrics (AAP) recommendations for vitamin D supplementation are daily supplementation of 400 IU vitamin D for breastfed infants, beginning with the first few days of life and continued until they are weaned to at least 1000 mL per day of vitamin D-fortified formula or milk, and for non- breastfed infants ingesting less than 1000 mL per day of vitamin D-fortified formula or milk, children and adolescents who do not get regular sunlight exposure, do not ingest at least 32 ounces per day of vitamin D-fortified milk, or do not take a daily multivitamin supplement containing at least 400 IU of vitamin D.
Most over-the-counter vitamin formulations contain D3 (cholecalciferol), which is more potent than D2 (ergocalciferol).
Calcium supplements are available in combination with vitamin D.
Calcitriol is most active form of vitamin D, and is available only by prescription.
Calcitriol does not require activation in the kidneys, it is the drug of choice for renally impaired patients.
Severe diarrhea and vomiting may be the cause of the deficiency of calcium.
It can occur in adults, but the majority of cases occur in children suffering from severe malnutrition during the early stages of childhood.
Osteomalacia is a similar condition that occurs in adults, generally due to a deficiency of vitamin D.
Patients may experience bone pain or tenderness, dental problems, muscle weakness, increased tendency for fractures, especially greenstick fractures, skeletal deformities of bowing of legs, knock-knees, lumbar lordosis, cranial, pelvic and spinal abnormalities, cartilage hyperplasia withwidening of the wrist, and growth disturbances.
Patients may have tetany.
Chest X rays show changes of costochondral swelling, referred to as Rosary beads.
Laboratory findings include hypocalclemia.
Changes in the skull can cause a distinctive “square headed” appearance.
Skeletal changes persist into adult life if not treated.
Nutritional rickets Is characterized by bone pain, leg deformities, and hypocalcemia, and occurs when deficiency of vitamin D or dietary calcium results in impaired mineralization of growing bone.
Nutritional rickets is associated with black race, breast-feeding, low birth weight, and stunted growth.
Nutritional rickets is rare, but it’s incidence is increasing.
The primary cause is a vitamin D deficiency.
In the absence of vitamin D, dietary calcium is not properly absorbed, resulting in hypocalclemia with skeletal and dental deformities and neuromuscular symptoms.
A rare X-linked dominant form exists called Vitamin D resistant rickets.
Rickets may be associated with hypocalcemia, hypophoshatemia, metabolic acidosis, and elevated serum alkaline phosphatase.
X-rays of affected bones may show loss of calcium from bones or changes in the shape or structure of the bones.
The most common treatment of rickets is the use of Vitamin D.
Surgery may be required to remove severe bone abnormalities.
Treatment involves increasing dietary intake of calcium, phosphates and vitamin D, and exposure to ultraviolet B light.
Recommendations are for 400 international units (IU) of vitamin D a day for infants and children.
Foods that contain vitamin D include butter, eggs, fish liver oils, margarine, fortified milk and juice, portabella & shiitake mushrooms, and oily fishes such as tuna, herring, and salmon.
Vitamin D3, cholecalciferol, is the preferred form since it is more readily absorbed than vitamin D2.
Production with exposure to sunlight is approximately 250 µg of vitamin D (10,000 IU) per day.
Darker skin patients produce less vitamin D than those with lighter skin, for the same amount of sunlight.
All infants, including those who are exclusively breast-fed, need Vitamin D supplementation until they start drinking at least 500 ml of vitamin D-fortified milk or formula a day.