Pregnancy test kit detects Pregnancy on the basis of the presence of which hormone?

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2024

Explanation

Pregnancy tests are based on detecting Human chorionic gonadotropin (hCG) in a woman's urine or blood.
hCG is a hormone produced by the trophoblast cells of the placenta starting shortly after implantation.
Its levels rise rapidly and predictably in early pregnancy, making it a reliable marker for confirmation.
The primary function of hCG is to rescue the corpus luteum, ensuring it continues to secrete progesterone, which is vital for maintaining the early pregnancy.

Option B: Prolactin is primarily responsible for lactation (milk production) after childbirth and breast development during pregnancy, not for the initial detection of pregnancy.
Option C: Luteinizing Hormone (LH) surges to trigger ovulation. While structurally similar to hCG, pregnancy tests are specific to the beta-subunit of hCG to prevent a false positive from LH.
Option D: Thyroid-stimulating hormone (TSH) is involved in regulating thyroid function and metabolism. It has no role in confirming pregnancy.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain The hormonal basis of pregnancy detection tests as background academic context rather than a clinical decision trigger.
Nurses educate patients on the correct timing and use of home pregnancy tests, explaining that testing too early may yield a false-negative result as hCG levels may not be high enough for detection.
Quantitative serum hCG tests are crucial in clinical settings to monitor the viability of an early pregnancy. A slow-rising or falling hCG level can indicate a potential miscarriage or an ectopic pregnancy, requiring prompt nursing assessment and intervention.
Abnormally high hCG levels can be a clinical indicator for conditions such as a molar pregnancy or multiple gestations (e.g., twins), prompting further investigation.

How to Approach the Question

First, identify the core subject of the question, which is the biological marker used in pregnancy tests.
Recall the key hormones associated with the female reproductive cycle and pregnancy.
Analyze the function of each option: Human chorionic gonadotropin (hCG) is known as the 'pregnancy hormone'. Prolactin is for milk. Luteinizing Hormone (LH) is for ovulation. TSH is for the thyroid.
Connect the function of each hormone to the question's requirement. The question asks what a pregnancy test detects.
Conclude that hCG is the only hormone produced specifically by the developing placenta in early pregnancy and is the target for all pregnancy tests.

Concept Tested & Keywords

Q3475vnxAUNZROEPz3vONR

E6 Physiology Ganong 27e Vol 2 Part 2 p. 13-15

E6 Obstetrics Williams pp. 71-94, 6

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