Vitamin C deficiency

Introduction Scurvy is a chronic disease caused by long-term lack of vitamin C (ascorbic acid, ascorbic acid). It is rare at present, but in the northern pastoral areas where vegetables and fruits are lacking, or in urban and rural areas, artificial feeding is neglected. Especially in rural remote areas, it is still caused by improper feeding. If the pregnant mother has proper nutrition, the child has a proper vitamin C reserve at birth, and the plasma vitamin C content of cord blood is 2 to 4 times higher than that of the mother plasma, so the incidence of infants less than 3 months is less.

Cause

Insufficient intake

If the pregnant mother has proper nutrition, the child has a proper vitamin C reserve at birth, and the plasma vitamin C content of cord blood is 2 to 4 times higher than that of the mother plasma, so the incidence of infants less than 3 months is less. However, if the pregnant mother's diet lacks vitamin C, the newborn can also suffer from scurvy. Normal human milk contains about 40-70 mg/L (4-7 mg/dl) of vitamin C, which can meet the needs of ordinary babies. The content of vitamin C 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. 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, there are few. Therefore, infants fed with cow's milk, goat's milk or unfortified milk powder, milk cake, batter, etc., if they do not supplement vitamin C, fruits or vegetables on time, are prone to scurvy. The scurvy in older children is caused by the lack of fresh vegetables and fruits in the diet.

2. Need to increase

When the metabolic rate increases, the amount of vitamin C is increased. When the growth is active, the vitamin C content of the body tissue is sharply reduced. Premature infants grow faster and faster, and the amount of vitamin C is relatively larger than that of normal infants. It should be supplemented more. When fever, acute or chronic infectious diseases such as diarrhea, dysentery, pneumonia, tuberculosis, etc., the amount of vitamin C is increased, such as long-term illness, and does not increase the intake of vitamin C, easy to be complicated by the severity of bad blood disease.

3. Other factors

Such as long-term intake of large amounts of vitamin C, its catabolism and increased renal excretion to reduce plasma vitamin C concentration. If a large amount of vitamin C is stopped, scurvy can occur. Long-term use of large amounts of vitamin C during pregnancy, newborns may still suffer from scurvy even if they consume regular amounts of vitamin C daily after birth.

an examination

Related inspection

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Typical scurvy has obvious symptoms and is easier to diagnose. It is difficult to diagnose recessive and early scurvy due to lack of specific symptoms. It should be combined with feeding history and other tests for comprehensive analysis.

1. Feeding history and clinical symptoms

Artificially fed babies are not supplemented with vitamin C supplements, or the lactating mothers lack fresh vegetables or fruits, or the lactating mothers are used to only pickles. The prevalence of scurvy (3 to 18 months), combined with some of the aforementioned non-specific symptoms and feeding history, can provide clues to the diagnosis of early scurvy. If the disease has progressed to a certain stage or advanced stage, it can be diagnosed according to symptoms such as swollen limbs, frog-shaped legs, gums and submucosal hemorrhage.

2. X-ray inspection

X-ray examination of the long bones of the extremities is extremely important for the diagnosis of this disease. Taking X-ray films from the knees, ankles, and wrists can provide a basis for early diagnosis of scurvy, especially a slightly thickened and irregular white sputum line (showing that the temporary zonal zone is thickened by the accumulation of calcium), A black dot with a full width or a black dot at a side angle below the sacral line, or a triangular defect (showing varying degrees of bone sparsity, a transparent slit or point on the X-ray film) is the disease feature. As the disease progresses, the following changes can be seen:

1 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 above-mentioned sparse point or sparse seam is enlarged to become a black belt of full width, which may be called "scurvy band";

3 The center of the ossified osteophytes is also like a frosted glass, surrounded by a distinct white loop line, and the most dense near the backbone end;

4 A small bone spur appears at the line connecting the two sides of the epiphysis to the thickened iliac line. Because of its position, it is called the lateral spur.

5 The shadow of the subperiosteal hemorrhage causes the affected long bone to be shaped like a scorpion or fusiform, sometimes bleeding at the two distal ends of the long bone, forming a dumbbell shape, and its contour is more clear after treatment;

6 In severe cases, there may be separation and dislocation of the epiphysis and the backbone; 7 the anterior end of the rib is widened, and the tip of the rib is like a tongue-like plate, which is easily distinguished from the cup-shaped end of the rib rib.

3. What the laboratory sees: Laboratory testing is far less helpful in diagnosing scurvy than in X-ray examination.

1 The plasma vitamin C concentration after fasting is >6mg/L (0.6mg/dl), which can rule out scurvy. However, lower concentrations do not confirm the presence of scurvy, and clinical diagnosis is often not parallel to plasma vitamin C concentrations. Specimens must be measured within 48 hours of collection.

2 The white blood cell-platelet layer (the yellow blood layer of the blood clot) which has been subjected to centrifugation by the oxalic acid-treated blood to determine the ascorbic acid concentration is a method for confirming the deficiency of vitamin C. The normal concentration is 280 ~ 300mg / L (28 ~ 30mg / dl), when its content drops to zero, although there is no clinical symptoms, it also shows recessive scurvy.

3 Another better method is the tolerance test, using ascorbic acid 20 mg / kg in physiological saline to make a 4% solution, intravenous injection. For example, after 4 hours, the amount of vitamin C in the urine sample is >15 mg/L (1.5 mg/dl), which can rule out scurvy.

4 When vitamin C is deficient, the vitamin C content in the urine is reduced in 24 hours (normal value is 20-40 mg). Although a large amount of vitamin C is added, the content of vitamin C in the urine cannot be normalized, because all tissues in the body need to be supplemented. The amount can be excreted by the urine until the whole body has reached saturation, and after the blood content is increased, excess vitamin C is excreted from the urine. 5 In addition, non-specific amino acid urine is seen in scurvy, but the blood amino acid value is still normal. The tyrosine loading test showed that metabolites excreted by scurvy infants were similar to those excreted by immature infants. Capillary fragility test may be negative in recessive scurvy, and positive scurvy is tested positive. Serum calcium and phosphorus were normal, alkaline phosphatase activity decreased, and the value decreased, as opposed to active rickets. In the late stage, there is obvious anemia, which is generally small cell-like. When the folate metabolism is impaired, large cell anemia can occur.

4. Therapeutic test: The treatment of scurvy with vitamin C has special effects and can be used to assist in diagnosis.

Differential diagnosis

Differential diagnosis of vitamin C deficiency:

1. Limb swelling and pain: should be differentiated from septic arthritis, osteomyelitis, cellulitis and deep abscess. These diseases are more common in unilateral limbs, and there are local redness and burning, systemic symptoms, high fever, poisoning and increased white blood cells, all of which are significantly different from scurvy. Rheumatoid arthritis is rare in infants younger than 2 to 3 years old, and is migratory, and other specific symptoms and signs of rheumatic fever can be identified.

Subperiosteal hemorrhage of scurvy sometimes needs to be differentiated from tumors, but other symptoms of scurvy are easy to identify with tumors. If necessary, X-ray examination and treatment tests can be used to confirm the diagnosis.

The general symptoms and skeletal tenderness of infantile cortical hyperplasia are sometimes similar to scurvy, but the lesions are more common in the flat stomach, such as the jaw, scapula, calvaria, and clavicle. Frequent facial involvement, and sometimes involving the limbs, increased erythrocyte sedimentation rate and increased serum alkaline phosphatase, help identify. The age of onset is mostly during the 6 months after birth, and the scurvy is more than 6 months later. The course of cortical hyperplasia is very irregular. The short is several weeks, the elderly are several months, sometimes recurrent, and generally healed. X-ray examination showed bone hyperplasia and thickening of the cortex, which disappeared after several months and had no commonality with scurvy.

The onset age of limb pain is different from that of scurvy, and it has characteristic redness, itching and severe pain in the hands, feet, high blood pressure, sweating and shame. In severe cases, the fingers and toes become black and even fall off. Identification of easy and scurvy (see the poisoning section of the mercury poisoning section).

2. Limb false sputum: must be differentiated from polio, rickets, trauma, congenital syphilis, etc.: 1 poliomyelitis shows flaccid paralysis, no swelling and pain, and other peripheral symptoms, very different from scurvy; 2 The rickets have special signs and X-ray findings; 3 trauma cases should have a history of injury, and bilateral symmetrical injuries are rare. X-ray examination is very significant; 4 congenital syphilis occurs in infants under 4 months, mothers with phenotype or cryptic syphilis, children with specific signs of congenital syphilis, serological tests and X-ray long bone photography Identification.

3. Hemorrhagic symptoms: should be differentiated from other bleeding disorders: 1 thrombocytopenic purpura, allergic purpura, hemophilia, etc. can be identified according to platelet, bleeding and clotting time and other coagulation tests and family history; 2 leukemia bleeding, At the same time, blood and bone marrow have their characteristic changes; 3 septic epidemic cerebrospinal meningitis has neurological signs and cerebrospinal fluid changes, and it is easy to find pathogenic bacteria from the skin purpura and cerebrospinal fluid, easy to identify; 4 orbital hemorrhage and eyeball When prominent, it should be differentiated from neuroblastoma and chronic yellow tumor. The latter two have no other scurvy characteristics. 5 When the gum is bleeding, when it is differentiated from gingivitis, the latter is rare in infants, and its gums are mostly flushed and not accompanied. There are other symptoms of scurvy.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.