Chem Path Flashcards
List four (4) other biochemical tests that may be performed antenatally for screening of foetal anomalies (4x½ = 2)
PAPP-A, Estriol, Inhibin, Free or total beta human chorionic gonadotropin
The triple test is used to screen for Down syndrome in the second trimester.
Name the three (3) analytes measured in the triple test and state whether you would expect them to be increased or decreased in a positive screen (3)
decreased AFP, inctreased unconjugated estriol, increased hCG
Name two (2) other conditions which the triple test may diagnose (1)
Trisomy 18 (Edward syndrome), Neural tube defects
Dr Brown is called to evaluate a newborn infant in the labour ward. On physical exam he notes that the infant has normal vital signs and appearance with the following exception. Dr Brown notes that the infant has a bulging cyst-like structure approximately 4 cm in diameter protruding from his back. He also observes that the baby has limited movement of the lower extremities and that both feet are plantar flexed and inverted at the ankle.
Dr Brown finds a report for antenatal biochemical testing performed on the mom during this pregnancy.
State the biochemical analyte in maternal serum that would be elevated in this case (½)
Alpha-fetoprotein
State the mechanism for the increase of this analyte (1)
Neural tube defects: The open nature of the neural tube allows the transudation of AFP from foetal serum directly into amniotic fluid in amounts greater than might be expected physiologically. This then results in increased amounts of AFP in maternal serum.
State one other pregnancy-related condition where this analyte will be elevated in maternal serum (½)
Multiple pregnancy; foetal conditions (renal disease, abdominal wall defects)
List two (2) non-pregnancy-related conditions in which this analyte is elevated (2x½ = 1)
Non-pregnancy-related: liver cirrhosis, hepatitis, hepatoma, non-seminomatous germ cell tumours
Name two conditions other than NTD (Neural Tube Defect) that would cause an elevated -foetoprotein (AFP) level in the serum of a pregnant woman (2)
Fetal nephrotic syndrome, fetal bowel atresias (oesophagus and anal), multiple pregnancy, oligohydramnios, fetal death, and hepatocellular carcinoma in mom
State the two (2) important biological roles of folate (2x½ = 1)
DNA synthesis, Myelin synthesis
Briefly outline and explain the clinical findings in folate deficiency (3x1 = 3)
Megaloblastic anaemia without neurological degeneration [2]
Myelin synthesis is prioritised over DNA synthesis. [1]
Briefly explain the increase in homocysteine seen with folate deficiency (1)
Folate (in the methyl-THF form) is a substrate (methyl donor) for methionine synthesis from homocysteine. [1]
