[Vitamin D deficiency rickets is a common nutritional deficiency in infancy and early childhood. It is a systemic chronic nutritional disease characterized by skeletal lesions due to the disturbance of calcium and phosphorus metabolism caused by vitamin D deficiency in children, which prevents normal deposition of calcium salts in the process of bone formation. Infants and children, especially small infants, are at high risk for nutritional vitamin D deficiency rickets because of their rapid growth and low outdoor activities. However, since the 1950s, China has been vigorously promoting the prevention and treatment of rickets, and in the 1980s, milk and other infant foods have been fortified with vitamin D. The incidence has been decreasing year by year, and the number of serious cases has been greatly reduced, but with the development of industrialization and urbanization, if we do not strengthen the prevention, rickets will tend to increase.
[Causes]
1, vitamin D intake and lack of light human vitamin D sources are two: one is endogenous, from the ultraviolet light in the sun directly irradiated human epidermis and dermis stored in the original vitamin D3 into vitamin D3. two is exogenous, through dietary and pharmaceutical preparations to obtain. In addition to the liver of some marine fish (e.g. shark), dairy (including human milk, cow and goat milk), egg yolk and meat contain very little vitamin D. Cereals, vegetables and fruits contain almost no vitamin D. The daily amount of vitamin D contained in natural foods is often insufficient for human needs, which mainly depend on sunlight exposure. However, regional latitude, season, clothing and air pollution affect the intensity of ultraviolet radiation, so the north, rainy and foggy areas, large cities and tall buildings can block sunlight; atmospheric pollution such as smog, dust can absorb part of the ultraviolet radiation; winter sunshine is short, ultraviolet light is weak; ultraviolet light can not penetrate the glass, infants and young children are too much long-term stay indoors activities. The above will make the endogenous vitamin D generation is insufficient.
2, congenital vitamin D reserve deficiency and overgrowth The mother’s gestation, especially late pregnancy vitamin D nutrition deficiency such as maternal severe malnutrition, liver and kidney disease, chronic diarrhea, as well as premature birth, twin births can make the infant’s body storage deficiency. At the same time, the infant grows too fast and needs more. Therefore, the northern winter and spring children, especially premature children are prone to rickets; adolescent growth accelerates, such as less sunlight, there can be late-onset rickets.
Vitamin D is fat-soluble, so gastrointestinal or hepatobiliary diseases affect vitamin D absorption, such as infantile hepatitis syndrome, congenital stenosis or atresia, steatorrhea, pancreatitis, chronic diarrhea, etc. When the kidney and liver are not functioning well, it can also cause vitamin D hydroxylation disorder, 1,25-(OH)2D generation deficiency and cause rickets.
4, the influence of drugs anticonvulsant drugs such as sodium phenytoin, phenobarbital to accelerate the metabolism of vitamin D in the body, so that the need to increase; glucocorticoids have to counteract the role of vitamin D on calcium transport. Long-term use can lead to rickets.
5. Insufficient calcium intake Natural foods such as milk are the richest in calcium, such as artificially fed children do not eat milk, fed with rice and flour paste, calcium intake is often insufficient. And cereals often contain more phytic acid can be combined with calcium to affect its absorption. In addition, improper calcium to phosphorus ratio also reduces absorption, so although cow’s milk contains more calcium than human milk, but its high phosphorus content, calcium absorption rate is not as good as human milk.
[Clinical manifestations] Mostly seen in infants and young children, with a high incidence from 3 months to 18 months, and an early onset in mothers with vitamin D deficiency during pregnancy. Rickets occurs less frequently in childhood.
1. Initial stage (early stage) Mostly seen in infants within 6 months of age, especially in infants within 3 months of age. Most of them show increased neuroexcitability, such as irritability, fussiness, head shaking due to sweating, night terrors, and occipital baldness. However, these are not specific symptoms of rickets, but only serve as a reference for early clinical diagnosis, and cannot be used to diagnose rickets. In this period, there is often no skeletal lesion, the skeletal X-ray may be normal or the calcification zone may be slightly blurred, serum 25-(OH)D3 decreases, PTH increases, blood calcium decreases, blood phosphorus decreases, and alkaline phosphatase is normal or slightly high.
2.Activity phase (radical phase) Infants with early vitamin D deficiency appear typical skeletal changes without treatment. within 6 months of age, infants show cranial softening (soft fontanelle side, ping-pong head) with large fontanelle and late closure. after 6 months of age, the cranial softening disappears, although the disease is still progressing. The main manifestations are as follows.
(1) Head: The frontal bone and the central part of the parietal bone are often gradually thickened, and by 7-8 months of age, the head becomes “square box-like”, i.e., square head (looking down from above), and the head circumference is also larger than normal.
(2) chest: ① rib beads, along the rib direction at the junction of ribs and rib cartilage can be and rounded bulge, from top to bottom as a bead-like protrusion, the most obvious to the 7th-10th ribs; ② chicken chest or funnel chest, about 1 year old children can see the thoracic deformity, the sternal stalk and adjacent cartilage protrude forward, forming a “chicken chest-like “(3) Hao’s groove, which is seen in children with severe rickets, due to the softening of the ribs and traction at the attachment of the diaphragm, resulting in a horizontal depression at the lower edge of the ribs of the child, namely the rib-diaphragm groove or Hao’s groove. Sometimes normal children have slightly higher rib margins on both sides of the thorax, which should be distinguished from the rib-diaphragm sulcus.
(3) Extremities: hand and foot bracelets, wrist and ankle can also form a blunt circular ring-like bulge, called hand and foot bracelets; O, X, shaped legs, due to bone softening and muscle joint relaxation, the child began to stand and walk after the double lower extremity weight bearing, can appear femur, tibia, fibula bending, the formation of severe knee inversion (O-type) or knee valgus (X-type) {normal 1 within the child has physiological bending and normal postural changes, such as the tip of the foot inward or outward, etc., which correct naturally after 3-4 years of age and must be differentiated}. After the child can sit and stand, ligamentous laxity can lead to spinal deformity; the start of sitting, standing and walking is delayed due to its reduced muscle tone and muscle strength, and abnormal gait can be present. In this period, the blood biochemistry is slightly low except for serum calcium, and the other indexes change more significantly. X-ray shows that the calcification zone of long bones disappears, the epiphysis is brush-like, cup-shaped changes, the epiphyseal cartilage disk widens (>2mm), the bone quality is sparse, the bone cortex becomes thin, there may be a bending deformity of the backbone or green branch fracture, and the fracture may have no clinical symptoms.
3, recovery period Any of the above periods after sunlight exposure or treatment, clinical symptoms and signs gradually reduce or disappear. Blood biochemical changes 25-(OH)D3, blood calcium, blood phosphorus and PTH gradually return to normal, and alkaline phosphatase decreases to normal level in about 1-2 months. After 2-3 weeks of treatment the epiphyseal X-ray changes improve, irregular calcification lines appear, later the calcification zone is dense and thickened, the epiphyseal cartilage disc <2mm, and gradually returns to normal.
4. Posterior period Most often seen in children after 2 years of age. Because of severe rickets in infants and children, there are different degrees of residual epiphyseal deformities without any clinical symptoms, normal blood biochemistry and disappearance of epiphyseal lesions on X-ray examination.
[The first step is to ask whether there is a history of lack of sunlight and insufficient intake of vitamin D. Newborns and infants of several months should also be asked about the history of maternal sunlight and intake of vitamin D and calcium and whether there are clinical symptoms of calcium deficiency. The most reliable diagnostic criteria are blood biochemistry and skeletal x-ray, of which serum 25-OHD level is the most reliable.
[Rickets is a disease that can be easily prevented and often caused by neglect. It is important to make it a household name and to get the full cooperation of each child’s parents so that everyone can develop the good habit of taking vitamin D in appropriate amounts during the year-round light exposure, cold season and rapid growth.
1. Appropriate light is the most effective, convenient and economical way to prevent rickets. More outdoor activities are beneficial for children and people of all ages to improve their health and reduce diseases. Insufficient sunlight and low UV content in winter in northern China should be supplemented with vitamin D
Pregnant women, lactating mothers and infants, children and adolescents in particular should pay attention to appropriate daily sun exposure. Summer sunshine should be less clothing, not excessive protection to block ultraviolet rays, can get refraction of ultraviolet rays in the eaves and the shade of trees. Ultraviolet rays cannot penetrate the window glass, must open the window sun. “Appropriate” is necessary, excessive sunlight anti-harmful to health, to comfortable, not damage the skin as the degree. After 2-3 weeks of life, infants can be allowed to spend time outdoors, and in winter, 1-2 hours of outdoor activity per day. Some studies have shown that allowing breastfed infants to be outdoors for 2 hours per week, exposing only the face and hands, can maintain infant blood 25-(OH)D3 concentrations in the low end of the normal range (>11ng/dI).
2.Vitamin D prevention
(1) Regular and quantitative oral vitamin D: Premature babies, low birth weight children, twin-born babies start supplementation with vitamin D 800IU/day 2 weeks after birth, and change the preventive amount after 3 months; full-term babies start supplementation with vitamin D 400IU/day 2 weeks after birth until 2 years old, and the dosage can be suspended or reduced in summer when there are more outdoor activities, and generally no additional calcium supplements can be taken. Normal breast-fed children should be fed with 400~800IU of vitamin D daily (400~600IU in southern China and 600~800IU in northern China). Pregnant women and lactating mothers should also take 400-800 IU of vitamin D daily, especially in winter. Pregnant women and lactating mothers should drink milk, take calcium supplements, eat foods rich in calcium, vitamin D and other nutrients, and take appropriate amount of vitamin D (800 IU/day) in the second trimester to help the fetus store sufficient vitamin D to meet the needs of growth and development for a period of time after birth. For children under 3 years of age and adolescents with insufficient sunlight, they should take quarterly doses of vitamin D at least once a year in autumn and spring, and the dose should be no more than 100,000~150,000.
(2) Vitamin D fortified foods: At present, various baby foods in China are generally fortified with vitamin D and various vitamins, including milk drinks and small foods. In order to avoid excessive or insufficient intake of vitamin D, the daily requirement of vitamin D should be generally publicized, so that parents can understand and grasp, and not to eat unreliable fortified foods.
[Treatment] Day care is the same as prevention, along with treatment with vitamin D.
The aim is to control the active period and prevent skeletal deformities, the principle of treatment should be mainly oral, the general dose is 50μg-100μg (2000IU-4000IU) or 1,25-(OH)2D30.5μg-2.0 μg, and after one month, the preventive dose was changed to 400 IU/day. Also take calcium with at least 200 mg of elemental calcium daily. For dietary calcium deficiency, take additional calcium supplements and increase the amount of milk consumed. There is no positive relationship between high dose vitamin D and treatment effect. It does not shorten the course of treatment, is not related to clinical staging, and the use of high-dose therapy for rickets lacks reliable indicators to evaluate the concentration of vitamin D metabolites in the blood, the toxicity of vitamin D, the occurrence of hypercalcemia, and the long-term consequences. Therefore, high-dose treatment should have strict indications. When severe rickets has complications or cannot be taken orally, high-dose intramuscular injection of vitamin D 200,000 IU can be given once, and the preventive amount should be changed after three months.
[Differential diagnosis]
1, congenital hypothyroidism 2 to 3 months after birth, the phenomenon of hypothyroidism begins to appear, and with the increase in age symptoms become more and more obvious, such as growth retardation, physical short, late teething, large fontanel and late closure. Abdominal distension, similar to rickets, but the child has low intelligence, a special face, blood TSH determination can be distinguished.
2, cartilage dystrophy this disease head large, forehead protrusion, long epiphysis expansion, chest beads, abdominal large and rickets similar. However, the limbs and fingers are short and thick, the five fingers are flush, the lumbar vertebrae protrude forward, and the hips protrude backward. Characteristic changes can be seen on skeletal X-rays, such as thick and short bending of long bones, widening of the dry skeletal end in the shape of a trumpet, but the outline is bright and neat, and other bones can be buried in the enlarged dry skeletal end.
3. Differentiation from rickets due to other etiologies
(1) Familial hypophosphatemia: this disease is mostly an X-linked genetic disease, the relevant genes have been located in Xp22.1-p22.2, a few autosomal recessive inheritance, there are also disseminated cases, the primary defect is renal tubular reabsorption of phosphorus and 25-(OH)D3 hydroxylation process disorders. Rickets symptoms occur mostly after 1 year of age, and active rickets manifestations remain after 2 to 3 years of age. Blood calcium is mostly normal, blood phosphorus is significantly lower, and urinary phosphorus is increased. For conventional therapeutic doses of vitamin D is ineffective, the dose must be increased, and oral phosphorus is required at the same time.
(2) Distal renal tubular acidosis: Insufficient hydrogen secretion from the distal tubule, loss of sodium and calcium from the urine, leading to secondary hyperparathyroidism, bone decalcification and rickets symptoms, and the vitamin D therapy is not effective. The child has significant skeletal deformities, short stature, metabolic acidosis, polyuria, alkaline urine (urinary PH>6), low blood calcium, phosphorus and potassium, and high blood chloride with symptoms of hypokalemia.
(3) Vitamin D-dependent rickets: autosomal recessive inheritance, two types: type I is a renal 1-hydroxylase defect, to 25(OH)D3 conversion to 1,25(OH)2D3 process is impaired, blood 25(OH)D3 concentration is increased; type II is a target organ 1,25(OH)2D3 receptor defect, blood 1,25(OH)2D3 concentration is increased. Both types show clinically severe rickets with significantly lower serum calcium and phosphorus, significantly higher alkaline phosphate, and secondary hyperparathyroidism. type I children may have hyperaminoaciduria; an important feature of type II children is hair loss.
(4) Renal rickets: chronic renal dysfunction due to congenital or acquired causes can lead to low blood calcium and disorders of calcium and phosphorus metabolism such as high blood phosphorus; secondary hyperparathyroidism causes widespread bone decalcification and rickets skeletal changes. The signs are more obvious in late childhood, forming a dwarf state.