Maple syrup urine screening

Maple diabetes screening is an important check in newborn screening. According to the clinical manifestations, maple syrup can be divided into classic type, intermittent type, intermediate type, thiamine reaction type and E3 deficiency type, of which the most common type is 75%. Basic Information Specialist classification: prenatal and postnatal examination classification: endocrine examination Applicable gender: whether men and women apply fasting: fasting Tips: Taboo before check: poor rest, improper diet, excessive fatigue. Normal value There is no research yet. Clinical significance Abnormal results: 1. Classical (neonatal): Infants are normal within 24 hours after birth, and symptoms of ketoacidosis appear after 1 week, manifested as feeding difficulties, vomiting, metabolic acidosis and neurological damage. Such as convulsions, increased muscle tone, and even muscle rigidity, angulation of the horns, but also increased muscle tension and relaxation, lethargy or coma. Patients may have hypoglycemia, but convulsions and coma are not caused by hypoglycemia, as these symptoms do not improve after hypoglycemia is corrected. If not properly diagnosed and treated, patients often die within weeks or months. This type is the most serious and the most common type of maple diabetes. Even if you survive treatment, you may have sequelae of mental retardation and damage to the nervous system. This type is common in the Mennonite population. 2. Intermittent type: This type of patient is often induced under stress, such as surgery, infection and frequent vomiting. The clinical manifestations at the time of onset are similar to those of the classic type, and there is ataxia. However, the BCKD complex activity residue of this type of patient is higher than that of the typical type, and 8% to 10% of patients can be close to normal, so the symptoms are mild, and severe cases can also be used. Death after the attack. Increased blood and urine branched-chain amino acid concentrations during intermittent episodes with hypoglycemia, hypokalemia, hyperammonemia, ketosis, and acidosis. At the MRT examination, the bilateral globus pallidus of the T2 phase showed a high signal change. 3. Intermediate type: In the neonatal period, there are also maple odor and mild symptoms in the urine, and later induced maple diabetes in other diseases. Mainly the symptoms and signs of involvement of the nervous system, the same as the classic type, but lighter, responding to treatment with large doses of vitamin B1. 4. Vitamin B (thiamine) reaction type: Vitamin B1 is a coenzyme of BCKD complex. When the activity of BCKD complex is decreased due to mutation of E1, E2 and E3 genes, a large amount of coenzyme mainly composed of thiamine pyrophosphate is required. . The clinical manifestations were also mild, and the high-dose (200mg/24h) vitamin B1 treatment showed efficacy after 3 weeks, but there were also infants who were effective with vitamin B110mg. 5. Dihydrogenacyl dehydrogenase (E3) deficiency type This type is due to the lack of BCKD-specific kinase, which is shared by all α-ketoacid dehydrogenase complexes, so in addition to the reduced BCKD complex activity, Impaired pyruvate dehydrogenase and α-ketoglutarate dehydrogenase cause neonatal acidosis, normal in children, post-systemic relaxation, low muscle tone, progressive ataxia and severe Symptoms and signs of neurological damage can die in childhood. People who need to be examined: Newborns with maple diabetes signs. Precautions Taboo before the examination: poor rest, improper diet, excessive fatigue. Requirements for inspection: Actively cooperate with the doctor's work. Inspection process 1. Urine check: (1) In the urine of a patient, since the α-keto acid produced by the metabolism of branched chain amino acids is discharged, there is a maple odor. The odorous substance in the urine is 4,5-dimethyl-3-hydroxy-2(5H)-furanone [4,5dimethyl-3-hydroxy-2(5H)-furanone], also known as Sotolone. (2) Determination of branched chain amino acids (including leucine, valine, isoleucine and other isoleucine): the corresponding keto acid excreted from the urine [ie 2-keto acid 4-methyl-2 ketone) 2-oxoacid4-methyl-2-oxopentenoate (KIC), 3-methyl-2-oxobutanoate (KIV), (S)-(SKMV), and (R)- 3-methyl-2-ketovaleric acid [(R)-3-methyl-2-oxopantanoate, R-KMV]. Schadewaldt et al. measured the concentration of each component in 10 blood and urine of typical maple diabetes. The results showed that the corresponding metabolites from the urine of the above-mentioned branched-chain amino acids were KIC (0.1%-25%) from low to high. ), KIV (0.14% to 21.3%), SKMV (0.26% to 24.6%), and R-KMV (0.1% to 35.9%), and the amount of free branched chain amino acids excreted in urine is small. (3) Qualitative determination of urinary ketone: Fresh urine samples were positive by adding a few drops of dinitrophenylhydrazine and 0.1 N HCl to produce a yellow diphenyl hydrazine precipitate. 2. Blood test: (1) Determination of branched-chain amino acids in blood: The concentration of branched-chain amino acids in blood can be directly determined by automatic amino acid analyzer or ion exchange chromatography or tandem mass spectrometry, including leucine, isoleucine, and other Isoleucine (alloisoleucine) and proline. Due to the reduced or absent activity of the BCKD complex, these branched-chain amino acids are elevated in blood, and especially the increase in leucine is more pronounced than the other three branched-chain amino acids. The amount of leucine in the normal human blood is very small, and it is elevated in this disease. Therefore, the determination of different levels of leucine in blood has diagnostic significance. Not suitable for the crowd Inappropriate crowd: None. Adverse reactions and risks No obvious complications and harms.

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