Vitamin C deficiency in children
Introduction
Introduction to vitamin C deficiency in children Vitamin C deficiency, also known as scurvy, is a chronic disease characterized by long-term lack of vitamin C (ascorbic acid, ascorbic acid), characterized by increased bone turnover and increased capillary permeability. Clinically, bone metastasis and hemorrhagic tendency, excessive keratotic hair follicle papules, surrounded by capillary hemorrhage, characteristic of the performance, is now rare, but in the northern pastoral areas lacking fresh vegetables, fruits, or city, township to artificial Where the feeding is neglected, or the ascorbate oxidase is released after being smashed, cut, squeezed, and torn, the boiling time is too long, and the dishes are placed for too long. basic knowledge The proportion of illness: 1% Susceptible people: children Mode of infection: non-infectious Complications: rickets malnutrition intracranial hemorrhage fracture
Cause
The cause of vitamin C deficiency in children
(1) Causes of the disease
Insufficient intake (45%):
If the pregnant woman is properly nourished, the child has a suitable vitamin C reserve at birth. The plasma vitamin C content of the cord blood is 2 to 4 times higher than that of the mother plasma. Therefore, the infants under 3 months have less incidence, but if the pregnant woman lacks vitamin C, the newborn Can also suffer from scurvy, normal human milk contains about 227.2 ~ 397.6mol / L (4 ~ 7mg / dl) of vitamin C, can meet the needs of the average baby, the vitamin C content in human milk is proportional to the amount of vitamin C in the lactating mother, If the lactating mother's diet lacks vitamin C, the baby may suffer from scurvy. The fresh animal milk contains less vitamin C than human milk. The content of milk is generally only 1/4 of that of human milk. After storage, disinfection and dilution, etc. Therefore, infants fed with cow's milk, goat's milk or unfortified milk powder, milk cake, batter, etc., if they don't add vitamin C, fruits or vegetables on time, are prone to scurvy, and bad blood in older children. The disease is caused by the lack of fresh vegetables and fruits in the diet.
Need to increase (30%):
When the metabolic rate increases, the vitamin C requirement increases. When the growth is active, the vitamin C content in the body tissue decreases sharply. The premature infants grow faster and faster. The vitamin C requirement is relatively larger than that of normal infants, and should be supplemented more. Hot sexually transmitted diseases, acute and chronic infectious diseases, such as diarrhea, dysentery, pneumonia, tuberculosis, etc., vitamin C needs increased, such as long-term illness, and did not increase vitamin C intake, easy to concurrent with different weights of vitamins C lack of disease.
Other factors (15%):
Such as long-term intake of a large amount of vitamin C, its catabolism and renal excretion increased to reduce plasma vitamin C concentration, such as sudden withdrawal of large amounts of vitamin C, vitamin C deficiency can occur.
Long-term use of large amounts of vitamin C during pregnancy, even if the newborn intake of conventional amounts of vitamin C every day after birth, may still suffer from vitamin C deficiency.
(two) pathogenesis
Vitamin C is essential for the formation of normal collagen in the human body. The amount of vitamin C contained in the adrenal gland and the lens of the eye is particularly high. Vitamin C has a strong reducing property, has an important antioxidant function, and can reduce superoxide and Other active oxides protect DNA, protein and membrane structures and are involved in scavenging free radicals.
1. The pathogenesis of vitamin C deficiency
(1) Vitamin C can activate hydroxylase: Vitamin C is an important cofactor for prolyl hydroxylase and lysyl hydroxylase, which are essential for collagen biosynthesis, and can be enhanced. The activity of hydroxylase and oxidase, due to the reversibility of its redox ability, is active in microsomal electron transport and plays an important role in preventing collagen depolymerization and maintaining matrix integrity. Vitamin C deficiency can lead to collagen. Fiber formation disorders, decreased intercellular binding, stagnant dentin and bone-like tissue formation, increased capillary wall brittleness, delayed wound healing, etc.
(2) Vitamin C has strong reducibility: it can reduce ferric iron to divalent iron in the body, which is beneficial to the absorption of iron in the intestine and the synthesis of hemoglobin and the formation of ferritin in the liver, which can turn folic acid into Tetrahydrofolate promotes the maturation of red blood cells; it also promotes the synthesis of certain adrenal and pituitary hormones, immunoglobulins and neurotransmitters, and is associated with leukocyte phagocytosis, which enhances human immune function. Vitamin C deficiency can cause folic acid and Iron metabolism disorders cause a series of lesions such as anemia.
(3) Antioxidant function of vitamin C: Vitamin C can scavenge free radicals and prevent oxidative damage in the body. Since the 1990s, a lot of research work has been done. Vitamin C can promote the conversion of cholesterol in the liver to be soluble in water. Cholate increases secretion, lowers blood cholesterol levels, reduces cardiovascular diseases, hypertension and other chronic diseases, and reduces the risk of cataracts and cancer.
(4) Vitamin C is involved in the metabolism of aromatic amino acids: tyrosineuria may occur in scurvy; in the neonatal period, transient tyrosine is usually too high in low birth weight infants; high protein emulsion in premature infants such as high protein emulsion Feeding, urine often discharges a lot of tyrosine and phenylalanine, which can be corrected with vitamin C.
2. Pathological changes in vitamin C deficiency: mainly due to bleeding and bone changes caused by lack of collagen, the following lesions may occur:
(1) Connective tissue formation disorder: lack of binding between capillary endothelial cells, resulting in capillary fragility and increased wall permeability.
(2) Bone lesions: mostly at the rib cartilage junction and long bone end, especially near the wrist, knee and ankle joint. Due to the lack of matrix, the formation of bone-like tissue and ossification of the cartilage are impaired, but the calcination of the cartilage matrix Continued, characterized by temporary accumulation of calcium in the temporary calcification of the metaphysis, formation of a temporary calcification zone dense thickening, inhibition of osteogenesis, can not form bone tissue, the formed trabecular bone becomes brittle and easy to fold, metaphyseal bone Fragile, often lead to fracture and osteophyte separation, the original cortical bone and cancellous bone due to internal absorption of general bone atrophy, epithelium loosening, subperiosteal hemorrhage.
(3) Tooth lesions: dentate cell layer degeneration, gingival papillary hyperplasia and granulation tissue growth, gingival congestion and edema, and then gradually necrosis, loose teeth due to collagen deficiency, this lesion is common in children who have teething, severe cases can be There are skeletal muscle degenerative diseases, cardiac hypertrophy, myelosuppression and adrenal atrophy.
Prevention
Vitamin C deficiency prevention in children
1. Pregnant women and lactating mothers: prevent vitamin C deficiency in pregnant mothers and breastfeeding women. Eat more foods rich in vitamin C such as fresh fruits and vegetables.
2. Scientific feeding: Promote breastfeeding. Breastfeeding should be supplemented with vitamin C-rich foods for 4 months after birth. Artificial feeding should be supplemented with vitamin C-rich food supplements 1 month after birth. Generally, vitamin C needs 30 children per day. 50mg, premature infant l00mg, should be added when suffering from infectious diseases.
Complication
Pediatric vitamin C deficiency complications Complications, rickets, malnutrition, intracranial hemorrhage
1. Concurrent rickets, malnutrition: This disease can be combined with rickets and malnutrition. When rickets occur, the different manifestations of these two diseases appear on the X-ray film, which leads to confusion.
2. Intracranial hemorrhage: intracranial hemorrhage can occur.
3. Concurrent infection: the child's resistance is reduced, often complicated by infections such as otitis media, rickets, pneumonia and so on.
4. Fracture: due to the lack of matrix, the formation of bone-like tissue and intraosseous ossification, the osteogenesis is inhibited, bone tissue can not be formed, the trabecular bone becomes brittle and easy to break, the metaphyseal bone is fragile, often leading to fracture and Separation of the epiphysis.
Symptom
Symptoms of vitamin C deficiency in children Common symptoms Vitamin C deficiency pale pale spots, skin, bone marrow, bone loss, appetite loss, skin mucosal bleeding, diarrhea, eyeballs, iron deficiency anemia
It can occur at any age and is more common in children aged 6 to 24 months.
1. Systemic symptoms: Slow onset, from the lack of vitamin C in the diet to the development of vitamin C deficiency, about 4 to 7 months, often have some non-specific symptoms such as: burnout, weakness, agitation, loss of appetite, weight loss and Pale, such as vomiting, diarrhea and other symptoms of digestive disorders, often do not attract the attention of parents, this stage can be called recessive cases.
Generally, there is low fever, which is related to bleeding. When there is a complication, the body temperature is obviously increased, the pulse is increased, the sympathetic nerve may be caused by leg pain, and the breathing is shallow, which may be related to rib pain.
2. Bone lesions: The lower limbs are especially common in the calf swelling and pain. The swelling is more along the humeral shaft. The tenderness is significant. The local temperature is slightly increased, but it is not red. At the later stage of the disease, the affected part often maintains a certain position: two legs Outreach, the calf bends like a frog, and does not want to move. It is a false sputum. Due to severe pain, it is feared that his leg will be touched. When people walk in, they will cry with fear and the lower extremity is caused by subperiosteal hemorrhage. There is no depression when the finger is pressed.
The ribs and the costal cartilage meet sharply, forming scurvy beading, and the inner side of the convex part can be concave. This is due to the semi-dislocation of the sternum at the junction of the rib and the costal cartilage, and the beading of the rickets The epiphyseal cartilage band is widened, and the bulge is bilaterally symmetrical, without such a depression.
3. Bleeding symptoms: Hemorrhage of different sizes and degrees can occur in any part of the body, which can be in the skin, mucous membrane, subperiosteum, joint cavity and intramuscular hemorrhage, common long subperiosteal hemorrhage, especially the lower end of the femur and the proximal end of the humerus; Bleeding may not be easily detected by X-ray examination until the recovery period begins with surface calcification. In severe cases, there may be skeletal muscle degenerative diseases, cardiac hypertrophy, myelosuppression and adrenal atrophy, and skin defects and ecchymoses are more common in bones. In the vicinity of the lesion, the knee and the ankle are the most common, and other parts of the skin may also have defects. The gums often bleed under the mucous membrane. Most of them are found in the upper incisor. It can also be seen in the place where the molars or incisors are erupted, the gums are purple-red, the swelling is smooth and crunchy, and the blood can be hemorrhage with a slight compression. If the swelling area is enlarged, the teeth can be covered, and the surface can be covered with blood, such as the continuation of the fungus. Infection can cause local necrosis, rancidity and tooth loss, eyelids or conjunctiva can also bleed, making the eyes form a blue-purple, orbital subperiosteal hemorrhage Proptosis, terminally ill patients, and occasional gastrointestinal tract, genitourinary tract and meningeal hemorrhage, red blood cell about one-third of patients in urine, but rarely seen naked eye hematuria.
In addition, when elderly children suffer from vitamin C deficiency, they sometimes show keratosis of skin follicles, and their appearance is difficult to distinguish from those caused by vitamin A deficiency. Infants and young children are often accompanied by megaloblastic anemia, due to folic acid metabolism disorders. It may also lack folic acid; it may also be combined with iron deficiency anemia due to the absorption and utilization of iron.
Examine
Pediatric vitamin C deficiency check
Assessment of vitamin C nutrition levels in the body:
1. Plasma vitamin C content: normal value 0.5% ~ 1.4mg%, children below this value.
2.24h vitamin C quantification: normal value 20 ~ 40mg, children less than 20mg.
3. Vitamin C load test: After oral administration of 500 mg of vitamin C, the discharge amount in the urine of 4 hours is normal, and 1 to 3 mg is insufficient.
Laboratory inspection:
1. X-ray examination: X-ray examination of the long bones of the extremities is extremely important for the diagnosis of this disease. X-ray films taken from the knees, ankles and wrists can be used to obtain the basis for early diagnosis of scurvy, especially slightly thickened and not A neat white squall line (showing that the temporary calcification band is thickened by the accumulation of calcium), a black seam with a full width or a black dot at the side angle, or a triangular defect (showing varying degrees) The bone is sparse and is a translucent slit or point on the X-ray film.
As the disease progresses, the following changes can be seen:
(1) Increased transparency of the backbone: the cortical bone is thinned and the trabecular bone structure is atrophied, resulting in increased transparency of the backbone, such as ground glass.
(2) The appearance of scurvy zone: The above-mentioned sparse point or sparse seam increases to become a full-width black band, which may be called "scurvy band".
2. Capillary fragility test: The beam arm test showed an increase in capillary fragility, and more than 70% of the tests were positive.
Diagnosis
Diagnosis and identification of vitamin C deficiency in children
diagnosis
The disease is life-threatening but easy to treat. The feeding history should be asked in detail. Typical scurvy has obvious symptoms and is easy to diagnose. It is difficult to diagnose hidden and early scurvy due to lack of specific symptoms. It should be combined with feeding history and other examinations. For comprehensive analysis.
1. Feeding history and clinical features: artificial feeding children do not add food supplements containing vitamin C, or lack of fresh vegetables or fruits in the breast milk diet, or lactating mothers only eat pickles, etc., the age of scurvy (3 to 18 months) ), combined with some of the aforementioned non-specific symptoms and feeding history, can provide clues for the diagnosis of early scurvy, such as the disease has developed to a certain stage or advanced stage, according to limb swelling, frog-shaped legs, gums and submucosal bleeding, etc. Symptom diagnosis.
2. X-ray examination: can be based on the early diagnosis of vitamin C deficiency and the characteristics of the disease, such as "scurvy band".
3. Responsiveness after vitamin C treatment: rapid improvement after vitamin C treatment can make a diagnosis.
Differential diagnosis
According to the dietary history of vitamin C deficiency, typical clinical manifestations and long bone X-ray examination changes and rapid improvement after vitamin C treatment can make a diagnosis, but need to pay attention to the limb swelling and painful diseases such as osteomyelitis, suppurative joints Identification of inflammation; scurvy rib beads and rickets; limb pseudo sputum and polio identification; bleeding symptoms and other bleeding diseases such as hemophilia.
