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Somewhat school work > Chemical pathology C22 > Flashcards

Chemical pathology C22 Flashcards

1
Q

What happens to the level of hormones and peptides produced by the placenta as the size increases

A

the levels of hormones increases with exception of hCG as the levels peak before the end of the first trimester

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2
Q

name four major placental hormones

A

hCG
progesterone
oestrogen
HPL

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3
Q

name three other hormones and peptides used in prenatal screening

A

Inhibin (peptide)
PAPP-A (peptide)
AFP (peptide)

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4
Q

What is hCG made by and what are the two subunits it has

A

it is made by syncytiotrophoblats of the placenta and has a alpha and beta subunit

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5
Q

what hormones is the alpha subunit common to?

A

TSH
FSH
LH

and they are encoded by a single gene

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6
Q

what is special about the beta subunit

A

it is unique to hCG

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7
Q

what is the function of hCG

A

it stimulates the corpus luteum to continue producing progesterone in early pregnancy until the placenta is able to produce enough progesterone to maintain pregnancy

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8
Q

what is the first hormone produced by the placenta

A

hCG

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9
Q

how long after conception can hCG levels be detected and when does it reach maximum levels

A

3 weeks and this means that hCG levels can be detected before the first missed period

it reaches maximum levels between 8 and 12 weeks and from then onwards the levels gradually decline as the placenta takes over the production of progesterone

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10
Q

what affects the interpretation of hCG levels

A

the antibody used in the lab assay

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11
Q

what is the diagnostic purpose of hCG

A

used to confirm pregnancy (for obvious reasons)
marker for trophoblastic disease (tumour marker)
retained products of conception
prenatal screening
used to confirm expected gestation age BUT does not establish gestation age as the ranges are too wide and people with multiple previous pregnancies tend to have higher levels of hCG

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12
Q

what type of hormones are progesterone and oestrogen

A

steroid hormone and it is produced from cholesterol (derived from maternal cholesterol)

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13
Q

what produces progesterone and oestrogen

A

at first it is the corpus luteum under hCG instructions then it is the produced by the placenta

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14
Q

what is the function of progesterone

A

prevents menstruation and maintains the endometrium for implantation of the blastocyst and placental invasion

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15
Q

what organs play a role in the production of oestrogen in pregnancy

A

the placenta
foetal adrenal gland
foetal liver

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16
Q

what is the primary oestrogen of pregnancy

A

Oestriol (E3)
- 10% unconjugated and the rest is conjugated (sulphate and glucuronate)

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17
Q

What is the function of oestrogen in pregnancy

A

maintains fetal and uterine well-being

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18
Q

what is HPL (human placental lactogen) similar to?

A

growth hormone and to a lesser extent it is also similar to prolactin

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19
Q

what is the function of HPL

A

in the mother it prevents uptake of glucose and promotes lipolysis in order to provide glucose for the fetus while the mother uses the fatty acids for energy
it also prepares mamillary glands for lactation

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20
Q

what is the function of Activin and Inhibin

A

they are regulators for GnRH, hCG and steroids

  • inhibin is a negative feedback regulator of FSH and the placenta secretes large amounts of inhibin to prevent rise in FSH
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21
Q

where are Activin and Inhibin produced

A
  • ovaries
  • pituitary
  • placenta
22
Q

what is the function of PAPP-A (Pregnancy associated plasma protein A)

A

it is a metalloproteinase which is responsible for cleaving insulin-like growth factor binding protein

23
Q

where is PAPP-A produced

A

by the syncytiotrophoblast

24
Q

which hormone is similar to AFP

A

albumin. (AFP is the fetal albumin)

25
Q

where is AFP produced

A

initially in the yolk sac and then in the fetal liver

26
Q

when do the AFP levels peak

A

after the first trimester and then decrease to reach adult levels at 10 months of age

27
Q

what is AFP used for?

A

it a marker for hepatocellular carcinoma and germ cell tumors

28
Q

what is the purpose of prenatal screening

A

this is a non invasive test used to determine the risk that a particular disease is present in the unborn fetus

29
Q

what is important to note about prenatal screening

A

it does not provide a diagnoses as it uses protein levels and peptides that are usually elevated in particular diseases and uses that as a risk checker

30
Q

what are the characteritics of a good screening test

A

should not be expensive
easy to perform
safe and non invasive
give reproducible results
must be able to detect disease or condition on time
must be sensitive: must have a low false negative rate

31
Q

when is prenatal screening important

A

pregnancy at the age of 35 and above
family history of:
neural tube defects
chromosome abnormalities
single gene disorders
previous child with conditions

abnormalities identified during pregnancy

32
Q

what is the importance of prenatal screening

A

gives the health care practioner the risk ratio and informs them if they need to proceed and perform a prenatal diagnostic test.

33
Q

what is the function of prenatal diagnostic testing

A

the intended purpose is to come up with a definitive diagnosis

this is usually invasive and procedures carry higher complication risks

34
Q

give two examples of prenatal diagnostic testing

A

Amniocentesis and Chorionic villus sampling

35
Q

what happens with Amniocentesis

A

it is performed at 15 to 18 weeks of gestation and amniotic fluid is obtained transabdominally under ultrasound guidance

tests for karyotype, DNA analysis, biochemistry and enzyme studies

the complications include miscarriage, transient amniotic fluid leakage and intrauterine infection

36
Q

what happens with Chorionic villi sampling

A

performed at 8 to 13 weeks of gestation
developing placenta is obtained transcervically or transabdorminally

test for karyotype, DNA analysis and enzyme studies

the complication is grater than in amniocentesis and include miscarriage, infection, bleeding and limb defects and also cause contamination of martenal tissue

37
Q

what are the two types of prenatal screening

A

imaging - ultrasound, MRI and Doppler
Maternal serum biochemistry - AFP, PAPP-A, free beta hCG, total hCG, unconjugated oestriol and inhibin

38
Q

MoM=

A

patient results / median for GA

39
Q

what increases the incidence of neural tube defects

A

dietary folate deficiency

40
Q

name three types of neural tube defects

A

spina bifida, meningomyelocele and anencephaly

41
Q

what happens to AFP in neural tube defects

A

leaks through amniotic fluid through the neural tube defect and passes across the placenta into the maternal serum

42
Q

what is the MoM in neural tube defects

A

2 to 2.5

43
Q

what characterisis down syndrome

A

trisomy 21

44
Q

what increase the risk of bearing a child with down syndrome

A

pregnancy after the age of 35

45
Q

what can you expect to find on ultrasound for children with down syndrome

A

increased nuchal translucency
- thickness of subcutaneous fluid at the back of the neck
in 75% cases of D.S nuchal translucency is greater than 95 percentile

46
Q

down syndrome screening (first trimester)

A

ultrasound nuchal translucency is increased
PAPP-A is decreased (<0.5MoM)
Free beta hCG is increased (>1.5 MoM)

47
Q

down syndrome screening (second trimester)

A

AFP decreased
unconjugated oestrial is decreased
total hCG is increased
Dimeric inhibin A is increased

48
Q

what is Edwards syndrome

A

trisomy 18
this has a poor prognosis

49
Q

Edwards syndrome screening (first trimester)

A

ultrasound NT is increased
PAPP-A is decreased
free beta hCG is decreased

50
Q

Edwards syndrome screening (second trimester)

A

AFP is decreased
unconjugated eostrial is decreased
total hCG is decreased

Somewhat school work (13 decks)

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