study_ing
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i tot this wud be relevant here...im sure u guys will answer this better!
A 1-week-old newborn has had poor feeding, vomiting, and progressive lethargy over the past 4 days. She was born at term; pregnancy, labor, and delivery were uncomplicated, and she had no congenital anomalies. She is being breast-fed. She has a healthy 2-year-old brother; a sister died at 10 days of age after a full-term birth. Examination shows decreased muscle tone and poor responsiveness; reflexes are normal. Serum bicarbonate level is 8 mEq/L, pH is 7.15, and plasma ammonia level is 10 times the upper limit of normal. Which of the following is the most likely cause?
A) Mitochondrial disorder
B) Mucopolysaccharidoses disorder
C) Organic acid metabolism disorder
D) Renal tubular acidosis
E) X-linked leukodystrophy
expalnations please
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| blueocean
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C?[- organic acid metabolism disorders are AR inherited diseases with symptoms like you describe.
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| drpkaur
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C--here is some info on organic acid metabolism disorders
Newborn screening in Illinois includes testing for a panel of acylcarnitines. In some cases, an elevated level of a particular acylcarnitine may indicate the possibility of one of several different organic acid disorders; the specific disorder cannot be determined without further testing. It has been demonstrated that the following organic acid disorders may be detected using this panel:
Beta-ketothiolase deficiency (BKT) Glutaric aciduria type I (G Isovaleric acidemia (IVA) Methylmalonic acidemia (MMA) Propionic acidemia (PA) Malonic aciduria(MA) 2-methylbutyryl-CoA dehydrogenase deficiency (2MBCD) 3-hydroxy-3-methylglutaryl-CoA lyase deficiency (HMG) 3-methylcrotonyl-CoA carboxylase deficiency (3MCC)
3-methylglutaconic aciduria (3MGA) Multiple carboxylase deficiency (MCD) Clinical Symptoms
Many organic acid disorders present in the neonatal period. Typically, an affected newborn appears normal for the first days of life, but then may develop vomiting, poor feeding, failure to thrive, hypoglycemia, hyperammonemia, seizures, hypotonia and lethargy, progressing to coma. Common findings include ketosis, metabolic acidosis and, in some cases, an unusual odor. Many individuals affected with organic acid disorders have a significant risk of death during infancy.
Inheritance pattern
All of these disorders are inherited in an autosomal recessive pattern. As an autosomal recessive disorder, the parents of a child with one of these conditions are unaffected, healthy carriers of the condition, and have one normal gene and one abnormal gene. With each pregnancy, carrier parents have a 25 percent chance of having a child with two copies of the abnormal gene and the resulting organic acid defect. Carrier parents have a 50 percent chance of having a child who is an unaffected carrier, and a 25 percent chance of having an unaffected, non-carrier child. These risks would hold true for each pregnancy. All siblings of infants diagnosed with an organic acid disorder should be tested; and genetic counseling services should be offered to the family.
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| raves
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good info...thanks drpkaur.
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| study_ing
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ok guys ive forgotten most of this stuff..cud u please mention how u approach such a question. ..as in what do the high plasma levels of ammonia signify. or the plasma bicarbonate for example.
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| fox
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Probably the inc plasma bicarb is due to a compensatory respiratory alkalosis? I cant say the same for ammonia though.
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| tinabg
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In hyperamonemia all the hydrogen ions may be spent on binding to NH3 in the kidney to form NH4 so it can be excreted in the urine. Lack of hydrogen ions will cause metabolic alkalosis. What do you think?
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| tinabg
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Ignore my previous post. Both low bicarb and low ph are consistent with metabolic acidosis, which is caused by accumulation of organic acids in the blood
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