Vitamin D (vitamin D, VitD) has a wide range of physiological roles in maintaining normal growth and development of human tissues and cells. vitD does not act directly on target organs, but acts by binding to VitD receptors, so it is also a steroid hormone. vitD receptors are expressed in many tissues and cells throughout the body.
Vit D deficiency rickets (rickets of vitamin D deficiency) (referred to as rickets) is a systemic chronic nutritional disease characterized by skeletal lesions caused by abnormal calcium and phosphorus metabolism in the body due to Vit D deficiency, resulting in incomplete mineralization of bone tissue during the growth period. Rickets not only affects the normal growth and development of children, but also is related to VitD deficiency-related diseases, and is one of the four diseases focused on prevention and treatment in pediatrics in China. Under the leadership of the Ministry of Health, the National Scientific Research Collaborative Group for the Prevention and Treatment of Rickets formulated the “Prevention and Treatment Program for Infants and Children with Rickets” in 1986, which standardized the prevention and treatment of rickets. Since rickets is mostly found in infants and children under 3 years of age, this recommendation is mainly for infants and children with rickets.
I. Prevention
The occurrence of rickets is closely related to poor lifestyle. Rickets can be completely prevented and controlled by the comprehensive prevention and control measures of scientific child-rearing. The prevention of rickets should start from the perinatal period, with the focus on infants within 1 year of age, and should be managed systematically until the age of 3. That is to say, “grasp early, grasp small, grasp thorough”.
(I) Comprehensive prevention and control measures
Special emphasis is placed on the importance of parental and caregiver involvement. Make use of various forms of publicity to widely publicize scientific child-rearing and health knowledge about the prevention and treatment of diseases, correct poor child-rearing methods, and guide parents to participate in scientific health care.
(II) Systematic management
Carry out health care management for pregnant women, newborns, infants and children through maternal and child health care networks, and conduct regular follow-up visits and monitor rickets prevention and treatment according to the plan.
(3) Strengthening nursing care
Parents are instructed to provide proper health care and nursing care for children of all ages, regular vaccination, and active prevention of acute and chronic diseases such as upper respiratory tract infection, pneumonia, diarrhea, and anemia. Reasonable feeding, balanced diet and changing bad habits such as partial eating are very important to prevent rickets.
(4) Prevention during pregnancy
Pregnant women should be active outdoors frequently and eat foods rich in calcium and phosphorus. Women in the second trimester of pregnancy should take VitD 400-1000 U/d (10-25μg/d) as appropriate. If available, pregnant women should have their blood 25-(OH)D concentrations monitored during the second trimester of pregnancy, and if there is significant VitD deficiency, VitD should be supplemented to maintain 25-(OH)D levels in the normal range. VitA,D preparations should be used to avoid VitA toxicity, VitA intake <10,000 U/d
(V) Infants and children prevention
1. Outdoor activities: Parents should be instructed to take their infants outdoors as early as possible, gradually reaching 1-2 h/d, and exposing infants’ body parts such as head, face, hands and feet as much as possible.
2. VitD supplementation: Infants (including exclusively breastfed children) should receive 400 U/d (10 μg/d) of VitD for 2 weeks after birth until 2 years of age, and the amount of VitD supplementation should include the VitD content in food, sunlight exposure, VitD preparations, and VitD fortified foods. If infants consume 500m l of formula daily, they can take in about 200U (5μg) of VitD, and with appropriate outdoor activities (especially in summer when there are more outdoor activities), there is no need for additional VitD supplementation.
3, high-risk groups supplementation: premature babies, low birth weight babies, twins should be supplemented with VitD 800-1000 U/d (20-25μg/d) immediately after birth, and after 3 months to 400 U/d (10μg/d).
II. Diagnosis
(I) Risk factors for VitD deficiency
(1) Insufficient storage during fetal life: the fetus obtains VitD from the mother through the placenta and stores it in the body to meet its needs for a period of time after birth, and infants with VitD deficiency during maternal pregnancy, premature birth or twin-born infants have insufficient VitD in the early postnatal period.
2, lack of sunlight exposure: sunlight ultraviolet light can not pass through ordinary glass, infants and young children outdoor activities, VitD generation is insufficient; high-rise buildings block sunlight exposure, atmospheric pollution (such as smoke, dust) can absorb part of the ultraviolet light; winter sunlight exposure reduced, affecting the skin synthesis of VitD.
3, insufficient intake: natural food VitD content is low, such as dairy (including human milk and cow and goat milk, etc.), poultry egg yolk, meat and other content is low, cereals, vegetables, fruits almost do not contain VitD .
(II) Clinical manifestations
The clinical manifestations of rickets include non-specific symptoms, characteristic skeletal changes and other systemic changes.
The active phase of rickets is divided into early, radical, recovery and sequelae phases.
1. Early stage: It is mostly seen in infants within 6 months (especially within 3 months). There may be non-specific neuropsychiatric symptoms such as excessive sweating, occipital baldness, irritability, and night terrors. There are often no skeletal lesions at this stage. Blood calcium and phosphorus are normal or slightly low, alkaline phosphatase (AKP) is normal or slightly high, and blood 25-(OH) D is decreased. There is no abnormality in the long bone x-ray or the temporary calcification zone is blurred and thinned, and the dry marrow end is slightly widened.
2, radical phase: skeletal signs: <6 months old infants, visible signs of cranial softening (ping-pong sensation); >6 months old infants, visible signs such as square skull, hand (foot) bracelet, rib bead, rib cartilage groove, chicken chest, 0-shaped leg, X-shaped leg. Blood calcium is normally low or decreased, blood phosphorus is significantly decreased, and AKP is increased. Blood 25-(OH) D,1,25-(OH)2D was significantly decreased. Widening of the medullary end of the long bone trunk on bone X-ray, disappearance of temporary calcification zone, brush-like or cup-like, widening of the bone marrow cartilage disc >2 mm.
3.Recovery period: Early or active children’s symptoms disappeared after sunlight exposure or treatment, and the signs gradually reduced or disappeared. Blood calcium, blood phosphorus, AKP, 25-(O H)D ,1,25-(OH)2D gradually return to normal. The temporary calcification zone at the dry end of the long bones reappears, widens and increases in density on bone X-ray, and the skeletal cartilage disc <2 mm.
4. Posterior phase: Mostly seen in children after the age of 3 years, due to severe rickets in infancy and childhood, different degrees of skeletal deformities can be left behind. Generally, there are no clinical symptoms and normal blood biochemical examination.
In addition to skeletal lesions, Vit D deficiency can also affect other tissues and organs, causing delayed motor development, such as muscle relaxation and reduced muscle strength (muscle tone); and decreased immune function recurrent infections. Vit D deficiency in children may be associated with certain chronic diseases in adulthood, such as diabetes, asthma, multiple sclerosis, etc.
Vit D deficiency risk factors, clinical signs and symptoms help in the diagnosis, and blood biochemistry and bone radiographs are needed to confirm the diagnosis. Serum 25-(OH)D is the best indicator of VitD nutritional status and should be carried out gradually.
(III) Differential diagnosis
Vit D deficiency rickets needs to be differentiated from other non-VitD deficiency rickets (e.g. renal osteotropic disorder, renal tubular acidosis, hypophosphatemic anti-VitD rickets, Fanconi syndrome), endocrine and bone metabolic diseases (e.g. hypothyroidism, chondrodysplasia, mucopolysaccharidosis).
Children with chronic diarrhea or hepatobiliary or pancreatic diseases or taking anti-epileptic drugs can affect the absorption, metabolism, and transmutation of VitD in the body, resulting in secondary VitD deficiency, which also needs to be differentiated.
Treatment
(A) VitD treatment
The purpose of treatment is to control the disease and prevent skeletal deformities, the principle of treatment is mainly oral, VitD preparation selection, dose size, duration of treatment, single or multiple, route (oral or intramuscular injection) should be determined according to the specific circumstances of the child, emphasizing individualized administration.
If oral administration is difficult or diarrhea affects the absorption, high-dose assault therapy can be used. After 1 month of medication, follow-up should be conducted, and if symptoms, signs and laboratory tests do not improve, other diseases should be considered and differential diagnosis should be paid attention to, while hypercalcemia, hypercalciuria and VitD overdose should be avoided.
(II) Other treatment
1.Calcium supplementation: Milk is a reliable source of calcium nutrition for infants and children, and generally rickets treatment can be done without calcium supplementation.
2. Micronutrient supplementation: attention should be paid to the intake of other multivitamins.
3.Surgery: Severe skeletal deformity can be surgically corrected deformity.