folic acid

Folic acid is a water-soluble vitamin that is not found in nature and is not biologically active, but is a precursor of biologically active folate. Folate is widely found in nature, and is abundant in animals and plants, such as liver, kidney, green leafy vegetables, potatoes, and wheat bran. Folic acid can transfer a carbon group (methyl or formyl) to deoxyuridine to make it deoxythymidylate, which in turn synthesizes DNA. Basic Information Specialist classification: growth and development check classification: biochemical examination Applicable gender: whether men and women apply fasting: fasting Analysis results: Below normal: Folate deficiency can occur when the growth rate is too fast and the supply of folic acid is insufficient, the body's requirement for folic acid is increased, or the digestive tract is absorbed. Normal value: Serum folate: 4.3-31.7nmol/L Erythrocyte folate: 453.1-2666nmol/L Above normal: Taking too much folic acid can mask the early manifestations of vitamin B12 deficiency and cause damage to the nervous system. Taking folic acid 350 mg may affect the absorption of zinc, leading to zinc deficiency, which may cause fetal growth retardation and increase in low birth weight infants. negative: Positive: Tips: Oral contraceptives, phenytoin and other anticonvulsants will reduce the absorption of intestinal folic acid. Normal value 1. Serum folate is 4.3 to 31.7 nmol/L (1.9 to 14 μg/L). 2, red blood cell folate 453.1 ~ 2666nmol / L (200 ~ 1000μg / L) compact. Clinical significance 1, clinical diagnosis Folic acid deficiency can occur when the growth rate is too fast and the supply of folic acid is insufficient, the body's requirement for folic acid is increased, or the digestive tract is absorbed. If drugs that frequently use folic acid antagonists such as methotrexate can affect the uptake of folic acid by cells and inhibit the action of dihydrofolate reductase, hinder the formation of tetrahydrofolate; long-term use of antiepileptic drugs such as phenytoin and primidone can affect The absorption of folic acid, pyrimethamine and isoniazid also inhibit the action of dihydrofolate reductase, which can cause folic acid deficiency. The main manifestations of folic acid deficiency are anemia, others such as glossitis, tongue pain, atrophy of the tongue, smooth tongue, angular cheilitis and loss of appetite. Oral folic acid in the first month before pregnancy and the first trimester of pregnancy can prevent fetal neural tube defects. Folic acid is the most abundant in fresh vegetables, and is also abundant in liver, kidney and yeast, but less in meat and milk. The clinical manifestations of folate deficiency are similar to those of vitamin B12 deficiency, but there are no symptoms and signs of the nervous system when folic acid deficiency occurs. 2. Evaluation of laboratory diagnostic methods Determination of serum folate by microbiological methods is unstable and is only used as a reference method. Antibiotics, folate antagonists, serum lactobacillus antibodies or samples present in serum can be falsely reduced by exposure to sunlight. The radiation competitive protein binding technology is a relatively effective, rapid and precise assay method and has been widely used. Chemiluminescence technology is the most advanced method for the simultaneous determination of folic acid and vitamin B12. Erythrocyte folate determination is a good indicator for the diagnosis of chronic folate deficiency, reflecting the nutritional status of folic acid in tissues. Excessive folic acid can cause: 1, taking folic acid can mask the early manifestations of vitamin B12 deficiency, leading to damage to the nervous system. 2, taking folic acid 350 mg may affect the absorption of zinc, resulting in zinc deficiency, fetal growth retardation, low birth weight infants increased. 3, taking folic acid can interfere with the role of anticonvulsant drugs, induce convulsions in patients. 4, individual patients taking a large amount of folic acid for a long time can cause anorexia, nausea, abdominal distension and other gastrointestinal symptoms. 5, when a large amount of folic acid, yellow urine can appear. Low results may be diseases: folic acid deficiency in children, hepatic myelopathy, Crohn's disease in children, erythrocytic aplastic anemia in children, abnormal anemia in children with congenital erythropoiesis, hypothyroidism in the elderly, abnormalities in congenital erythropoiesis Anemia, anemia caused by excessive hemolysis, megaloblastic anemia in children, anemia caused by vitamin B12 deficiency First, the method for determining folic acid in red blood cells is the same as serum folic acid. Second, oral contraceptives, phenytoin and other anticonvulsants will reduce intestinal folic acid absorption. Third, patients receiving folic acid antagonistic drugs may occasionally see folic acid deficiency. Fourth, folic acid is a water-soluble vitamin, generally exceeds the minimum requirement of 20 times for adults and will not cause poisoning. Any amount that exceeds serum and tissue binding to the polypeptide is excreted from the urine. The toxic effects of taking large doses of folic acid are: 1. Interfere with the action of anticonvulsant drugs and induce seizures in patients. 2. Oral folic acid 350mg may affect the absorption of zinc, resulting in zinc deficiency, fetal growth retardation, and low birth weight infants. 3. Cover up the early manifestations of vitamin B12 deficiency, leading to damage to the nervous system. Inspection process 1, peripheral blood measurement: including red blood cells, white blood cells, platelet count, hemoglobin and hematocrit determination. The anemia of folate deficiency is large cell (MCV>100fl), often showing changes in the morphology and size of red blood cells, which may be accompanied by neutropenia and thrombocytopenia, especially in cases of long-term deficiency of folic acid, neutral The granulocyte enlargement is accompanied by excessive nuclear lobulation (nuclear right shift), and more than 5% of neutrophils have 5 lobes or more lobes. 2, bone marrow measurement: the most significant changes in giant red blood cells and large and abnormal neutrophils, accompanied by cytoplasmic vacuolization and nuclear lobulation of megakaryocytes. 3. Determination of serum folic acid: There are two methods of microbial and radioactive competitive protein binding techniques. Microbiological method is based on the principle that lactobacillus requires N-5 methyltetrahydrofolate during the growth process to monitor the growth of lactobacilli; the radioactive protein binding technique is based on the high affinity of folic acid for proteins, protein specific Combine these molecules. 4. Determination of folic acid in red blood cells: The amount of folic acid in the product of hemolysis of red blood cells was determined. In addition, whole blood folate, serum folate and hematocrit should be measured simultaneously. 5. Determination of urinary imine formyl glutamic acid: After histidine is converted into imidoformylglutamic acid in vivo, tetrahydrofolic acid is required to carry out the transfer of a carbon group to be converted into glutamic acid. In the absence of folic acid deficiency, the catabolism of the imidoformylglutamic acid is blocked and accumulates in the body, and is largely discharged from the urine. The reference value of normal human excretion is <3mg/24h, and the excretion amount can be increased by 1000mg/24h when folic acid deficiency is lacking. 6, paper blood sample folic acid detection method: the general blood test for folic acid is plasma, serum or dissolved blood, due to folic acid instability, light and heat are easily decomposed and inactivated, and such specimens in blood collection, blood sample treatment, The requirements for the storage and transshipment of specimens are strict. The method of collecting finger blood samples for detecting folic acid by using the filter paper method is a commonly used method in epidemiological investigations in foreign countries in recent years, and has the characteristics of small blood collection, simple operation, and economical convenience. The detection methods were hemoglobin folic acid determination and radioimmunoassay for detection of erythrocyte folic acid (correlation coefficient r=0.79 for both methods). Not suitable for the crowd Inappropriate people: Generally there are no people who are not suitable. Adverse reactions and risks 1. Infection: Pay attention to aseptic operation when collecting blood, avoid contamination of water and other parts at the blood collection site to avoid local infection. 2, bleeding: after the blood is given a full compression time, especially coagulopathy, bleeding tendency, to avoid local subcutaneous oozing, bruising and swelling.