Question

FIVE CLINICAL CHEMISTRY QUESTIONS:

1. What is the origin of AFP in the amniotic fluid? When do AFP levels peak in amniotic fluid? In maternal circulation? When should maternal blood levels be drawn?

2. What other test performed on amniotic fluid may confirm the diagnosis of a NTD? What values (elevated, decreased) will this assay take if a NTD is present?

3. Describe the delta O.D. spectrophotometric test for amniotic fluid bilirubin and discuss the clinical significance of abnormal results. (Include a description of Hemolytic Disease of the Newborn)

4. Briefly describe the changes in lipid composition of amniotic fluid before and during fetal lung maturation.

5. Describe the triple marker screen for Down syndrome and the expected changes from normal values for each in an affected pregnancy.

Answer 1

1. What is the origin of AFP in the amniotic fluid? When do AFP levels peak in amniotic fluid? In maternal circulation? When should maternal blood levels be drawn?

Alpha-fetoprotein (AFP, α-fetoprotein; likewise now and then called alpha-1-fetoprotein, alpha-fetoglobulin, or alpha fetal protein) is a protein. that in people is encoded by the AFP gene.

The AFP gene is situated on the q arm of chromosome 4 (4q25).

AFP is a noteworthy plasma protein delivered by the yolk sac and the liver amid fetal improvement. It is thought to be the fetal type of serum egg whites. AFP ties to copper, nickel, unsaturated fats and bilirubin and is found in monomeric, dimeric and trimeric forms.AFP is the most rich plasma protein found in the human hatchling. Plasma levels diminish quickly after birth yet start diminishing prenatally beginning toward the end of the main trimester.

Typical grown-up levels are generally accomplished by the age of 8 to 12 months. The capacity of AFP in grown-up people is obscure; be that as it may, in rodents it ties estradiol to keep the vehicle of this hormone over the placenta to the hatchling. The principle capacity of this is to keep the virilization of female embryos

Lifted alpha-fetoprotein alludes to a state where alpha-fetoprotein levels are outside of the reference go.

There are two classes of AFP tests: tests performed on serum (blood plasma), and tests performed on amniotic liquid. Tests performed on serum are further arranged by the purpose behind playing out the test: maternal serum, grown-up tumor marker, and pediatric tumor marker.

Maternal serum AFP (MSAFP) fluctuates by requests of greatness over the span of a typical pregnancy. MSAFP increments quickly until around 32 weeks growth, then abatements continuously. After the pregnancy closes it diminishes quickly, with a half-existence of around 5 days.

Normally, MSAFP is measured in the start of the second trimester (14–16 weeks). It might be measured alone or as a major aspect of a bundle of routine pre-birth screening tests, for example, a triple test or quad test.

Since MSAFP test comes about must be deciphered by gestational age, they frequently are accounted for as far as numerous of the middle (MoM). Since the middle is computed from trial of other ladies' pregnancies at the same gestational age, in actuality MoM is free of gestational age, however rely on upon exact gestational dating. A common ordinary range is 0.5 to 2.0 or 2.5 MoM.

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5. Describe the triple marker screen for Down syndrome and the expected changes from normal values for each in an affected pregnancy.

The Triple screen measures serum levels of AFP, estriol, and beta-hCG, with a 70% affectability and 5% false-positive rate. It is supplemented in a few areas of the United States, as the Quad screen (adding inhibin A to the board, bringing about a 81% affectability and 5% false-positive rate for identifying Down disorder when taken at 15–18 weeks of gestational age)[3] and other pre-birth conclusion strategies, in spite of the fact that it remains broadly utilized as a part of Canada[4] and different nations. A positive screen demonstrates an expanded danger of chromosomal irregularities (and neural tube surrenders), and such patients are then alluded for more delicate and particular systems to get an authoritative conclusion, regularly pre-birth determination by means of amniocentesis, in spite of the fact that the more grounded screening alternative of sans cell fetal DNA screening (likewise prevalently known as noninvasive pre-birth screening) is every now and again advertised. The Triple test can be comprehended as an early antecedent to a long line of resulting innovative enhancements. In some American states, for example, Missouri, Medicaid repays just for the Triple test and not other possibly more exact screening tests, while California offers Quad tests to all pregnant ladies.

The most widely recognized variation from the norm the test can screen is trisomy 21 (Down disorder). Notwithstanding Down disorder, the triple and fourfold screens evaluate hazard for fetal trisomy 18 otherwise called Edward's disorder, open neural tube surrenders, and may likewise distinguish an expanded danger of Turner disorder, triploidy, trisomy 16 mosaicism, fetal passing, Smith-Lemli-Opitz disorder, and steroid sulfatase inadequacy.

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