When might a false-negative result of PAMG-1 occur? If the specimen is collected 12 or more hours after a rupture that is subsequently obstructed by the fetus. What is presence of bilirubin in amniotic fluid an indicator of? Fetal erythroblastosis Why is it important to know the gestational age of the fetus when detecting bilirubin in amniotic fluid? Because the amount of bilirubin present in the amniotic fluid changes with gestational age. How is bilirubin measured in amniotic fluid? By a direct spectrophotometric method referred to as test When are some indications that a test for evaluating fetal lung maturity should be performed? before repeat cesarean delivery when the age of gestation is uncertain preterm labor premature rupture of membranes worsening maternal hypertension severe renal disease intrauterine growth retardation fetal distress What is the counting of Lamellar bodies used for? Assessing lung maturity. How are Lamellar bodies counted? Lamellar bodies have been counted directly using the platelet channel of whole blood cell counters (lamellar body count) What are Lamellar bodies produced by? Type II alveolar Does the quantity of Lamellar bodies increase or decrease as gestation advances? Increase What are Lamellar bodies counted on? Electronic cell counters. During the counting of Lamellar Bodies, what Lamellar Body Count (LBC) indicates fetal lung maturity? Greater than 50,000 counts/microliter What does the contamination with blood do to the lamellar body count? It decreases Lamellar Body Count What will contamination of the smallest amount of meconium do to lamellar body count? It dramatically increases Lamellar Body How does one perform a lamellar body count? With hematology analyzers using the platelet count channel. What lamellar body count is necessary to correspond to adequate fetal lung surfactant levels? Lamellar Body Count of 35,000 per microliter. What LBC indicates immature lung development? 0-15,000 counts/microliter What LBC indicates intermediate fetal lung development? 15,000- 50,000 counts/microliter What represents 85% of surfactants in the body? Lecithin
Why are surfactants important for assessing fetal lung maturity? require surfactant, a soap-like substance, to lower the surface pressure of the alveoli in the lungs. This is especially important for premature babies trying to expand their lungs after birth. During assessment of lung maturity what Lecithin/Sphingomyelin ratio (L-S ratio) indicates fetal lung maturity and decrease in respiratory distress syndrome? L-S ratio of 2 or more What L-S is considered high risk of respiratory distress syndrome? L-S ratio of less than 1.5 How is the amniotic collected and what must be done to it before determining the L-S ratio? An amniotic fluid sample is collected via amniocentesis and the sample is spun down in a centrifuge at 1000 rpm for 3–5 minutes. What is the best way to determine L-S ratio and why? Thin layer chromatography (TLC) on the supernatant. TLC is good because Lecithin and sphingomyelin are relatively easy to identify and the predictive value of the test is good. What is also tested with L-S ratio to determine the lung profile? Phosphatidylglycerol (PG) test is comined with L-S ratio to determine lung profile. As the gestation ages, what happens to the Phosphatidylglycerol (PG) concentration? The concentration of PG increases as gestation ages. What level of PG is considered positive on most TLC techniques? Greater than 2 µmol/L. What is Inborn Errors of Metabolism (IEM)? are genetically determined biochemical disorders affecting an individual’s ability to convert nutrients or to use them for energy production. They are caused by impaired activity of enzymes, transporters, or cofactors and result in the accumulation of abnormal metabolites (substrates). Typically present in newborn period or in infancy, but some may not be detected until adulthood. What is Abnormal Metabolites (Substrates)? It a substrate accumulation is block or deficiency product. What us Inheritance Pattern of Metabolic Disorders? Inheritance Pattern Metabolic disorders are caused by mutations in that code for specific enzymes or transporters involved in metabolic pathway. What is Autosomal Recessive Inheritance? It a mutation in both alleles encoding for specific enzyme or transporter. Because the mutation id a gene on a nonsex chromosome (autosome), girls are affected as often as boys.
How does the Second-tier testing involve? Involves further analysis of the same spot that produce an abnormal result targeting different, more specific analytes and, using a methodology different from the one used in the primary screening tests. How does the Second-tier testing requirement? Intended to reduce the number of infants requiring additional confirmatory testing. What are Newborn Screening tests? Such testing includes DNA analysis for cystic fibrosis, MS/MS steroid profiling for congenital adrenal hyperplasia, and TSH for congenital hypothyroidism. What are the three types in Inborn Errors of Metabolism disorders? Disorders of Amino Acid Metabolism Disorders of Fatty Acid Oxidation Disorders of Carbohydrate Metabolism What are Disorders of Amino Acid Metabolism known as Aminoacidopathies? Aminoacidopathies Phenylketonuria Tyrosinemia Homocystinuria Maple Syrup Urine Disease What are Disorders of Amino Acid Metabolism being as Organic Acidemias? Organic Acidemias Glutaric Acidemia Type I Isovaleric acidemia Methylmalonic acidemia Propionic acidemia How are Disorders of Fatty Acid Oxidation classified? Medium-Chain Acyl-CoA Dehydrogenase Deficiency (MCAD) Long-Chain 3-hydroxyacyl-CoA Dehydrogenase Deficiency (LCHAD) How are Disorders of Carbohydrate Metabolism Inborn Errors classified? Glycogen Storage Disease Glucose-6-Phosphate Dehydrogenase Deficiency Classic Galactosemia What is Aminoacidopathies? Parent amino acid accumulates in excess in blood and spills over into urine What is example of Aminoacidopathies? Phenylketonuria syrup urine disease Homocystinuria Tyrosinemia What do you called the disorder of amino acid of metabolism that’s accumulation of products in the catabolic pathway of certain amino acids? Organic acidemias What are examples of organic acidemias ? Glutaric acidemia type I Isovaleric acidemia Methylmalonic acidemia Propionic acidemia