Hormones - hCG Flashcards Preview

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Flashcards in Hormones - hCG Deck (13)
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1
Q

Source

A

Syncytiotrophoblast

Memory aid:

  • h_C_G
  • syn_C_ytiotrophoblast
2
Q

When detected? What is the implication?

A
  • When tested
    • 8 to 9 days after ovulation (in maternal serum or urine)
    • 6–12 days after fertilization (3–3.5 weeks after the LMP)
    • in maternal serum after implantation has taken place, ≈ 8–11 days after conception
  • Implication
    • Do not assay for hCG before a woman has missed a menstrual period because of low test sensitivity before this time
3
Q

Level

  • Peak
  • Plateau
A
  • Peak
    • 8 - 10 weeks
  • Plateau
    • 16 weeks
4
Q

Composition and origin

A

Glycoprotein (of two subunits—α and β) made by syncytiotrophoblast

5
Q

What subunit is the same with other hormone? What is the implication?

A
  • The α subunit
  • The β subunits are unique: Urine and serum tests are based on antibody specificity to β subunit of hCG

Memory aid: S_α_me

6
Q

The α-subunit is similar to what hormones?

A
  1. Luteinizing hormone (LH)
  2. Follicle-stimulating hormone (FSH)
  3. Thyroid-stimulating hormone (TSH)
  • Memory aid:*
  • FLαT
7
Q

Function of hCG

A

Helps sustain the corpus luteum during the first 7 weeks; after the first 7 weeks, the placenta makes its own hormones to sustain the pregnancy

8
Q

Rate of hCG increase

A

in general, hCG should double every two days prior to 10 weeks

9
Q

What if β-hCG does not rise as expected?

A

Consider accidents of pregnancy: spontaneous abortion, missed abortion, ectopic pregnancy

10
Q

Other conditions that produce hCG

A
  • Hydatidiform mole
  • Choriocarcinoma
  • Germ cell tumors
  • Breast cancers and large cell carcinoma of the lung
11
Q

In relation to hCG, when can gestational sac be visualized with TVS?

A

When hCG levels are > 1500

12
Q

What if the hCG is >1500 and no evidence of intrauterine pregnancy

A

Think ectopic pregnancy

13
Q

Urine hCG

  • Best time of collection
  • Level detectable by assay
A
  • Best time of collection
    • First morning specimens are more accurate
      • hCG concentration is higher in the morning
  • Level detectable by assay
    • 12.5 mU/mL