Endocrinology of Pregnancy — MCQs

Endocrinology of Pregnancy Indian Medical PG Practice Questions and MCQs

Question 61: What is the most sensitive method for the quantitative measurement of human chorionic gonadotropin?

A. Paper chromatography
B. Latex particle test
C. Radioimmunoassay (Correct Answer)
D. Male toad test

Explanation: **Explanation:** Human chorionic gonadotropin (hCG) is a glycoprotein hormone produced by the syncytiotrophoblast. For NEET-PG, understanding the evolution of pregnancy testing—from biological to immunological assays—is crucial. **Why Radioimmunoassay (RIA) is the correct answer:** Radioimmunoassay is the most sensitive and specific method for the quantitative measurement of hCG. It utilizes the principle of competitive binding between radiolabeled and unlabeled antigens for a specific antibody. RIA can detect hCG levels as low as **5 mIU/mL**, allowing for the diagnosis of pregnancy even before a missed period (approximately 8–10 days after fertilization). Modern variants like Chemiluminescent Immunoassay (CLIA) have similar high sensitivity. **Analysis of Incorrect Options:** * **Paper Chromatography:** This is a technique used for separating chemical substances (like amino acids or pigments) based on their solubility and movement through a medium. It is not used for hormone quantification. * **Latex Particle Test:** This is an immunological "slide test" based on agglutination inhibition. While faster than biological tests, it is a **qualitative** method with low sensitivity (detecting levels >500–1000 mIU/mL), making it unreliable for very early pregnancy. * **Male Toad Test (Galli-Mainini Test):** An obsolete biological assay where the injection of pregnant urine into a male toad caused the release of spermatozoa. These biological tests are historic, time-consuming, and lack sensitivity. **High-Yield Clinical Pearls for NEET-PG:** * **Structure:** hCG shares a common **alpha (α) subunit** with LH, FSH, and TSH. The **beta (β) subunit** is unique, which is why β-hCG assays are used to avoid cross-reactivity. * **Doubling Time:** In a healthy intrauterine pregnancy, hCG levels double every **48–72 hours**. * **Peak Levels:** hCG reaches its peak concentration (approx. 100,000 mIU/mL) at **8–10 weeks** of gestation. * **Discriminatory Zone:** The hCG level at which a gestational sac should be visible on TVS is typically **1500–2000 mIU/mL**.

Question 62: All of the following are risk factors for hyperemesis gravidarum, EXCEPT?

A. Hyperthyroidism
B. Twin pregnancy
C. Molar pregnancy
D. Gestational diabetes (Correct Answer)

Explanation: **Explanation:** Hyperemesis gravidarum (HG) is a severe form of nausea and vomiting in pregnancy characterized by weight loss, dehydration, and electrolyte imbalances. The underlying pathophysiology is primarily linked to high circulating levels of **Human Chorionic Gonadotropin (hCG)** and estrogen. **Why Gestational Diabetes is the Correct Answer:** Gestational Diabetes Mellitus (GDM) is **not** a risk factor for hyperemesis gravidarum. In fact, some studies suggest a potential inverse relationship, as HG is associated with a lower BMI and lower caloric intake in early pregnancy, whereas GDM is more common in patients with higher BMI and metabolic syndrome. **Analysis of Incorrect Options:** * **Molar Pregnancy (Hydatidiform Mole):** This condition involves an abnormal proliferation of trophoblasts, leading to pathologically high levels of hCG, which directly triggers the chemoreceptor trigger zone (CTZ). * **Twin Pregnancy:** Multiple gestations result in a larger placental mass and higher cumulative levels of hCG and estrogen compared to singleton pregnancies, significantly increasing the risk of HG. * **Hyperthyroidism:** hCG has a structural similarity to Thyroid Stimulating Hormone (TSH) and can weakly stimulate the TSH receptors (thyrotoxicosis of pregnancy). Conversely, pre-existing hyperthyroidism is associated with an increased risk of severe vomiting. **NEET-PG High-Yield Pearls:** * **Most common risk factor:** Previous history of hyperemesis gravidarum. * **Hormone most implicated:** hCG (specifically the peak levels between 8–12 weeks). * **Wernicke’s Encephalopathy:** A rare but serious complication of HG due to **Vitamin B1 (Thiamine)** deficiency; look for the triad of ataxia, ophthalmoplegia, and confusion. * **Electrolyte hallmark:** Hypokalemic, hypochloremic metabolic alkalosis.

Question 63: What is the characteristic change in the vagina during normal pregnancy?

A. Increased pH
B. Increased number of lactobacilli (Correct Answer)
C. Increased glycogen content
D. Increased number of pathogenic bacteria

Explanation: **Explanation:** The vaginal environment undergoes significant physiological changes during pregnancy, primarily driven by high levels of **estrogen**. 1. **Why Option B is Correct:** Estrogen causes the vaginal epithelium to thicken and accumulate high levels of **glycogen**. *Lactobacillus acidophilus* (Döderlein’s bacilli) ferment this glycogen into **lactic acid**. This symbiotic relationship leads to a proliferation of lactobacilli, which serve as a protective mechanism against ascending infections. 2. **Why Option A is Incorrect:** Due to the increased production of lactic acid, the vaginal **pH decreases** (becomes more acidic), typically ranging between **3.5 to 6.0**. An increased pH would indicate an abnormality, such as Bacterial Vaginosis. 3. **Why Option C is Incorrect:** While glycogen content *does* increase, it is the **substrate** for the process, not the primary characteristic change listed in the context of the vaginal flora's response. In NEET-PG, when choosing between the "cause" (glycogen) and the "result" (lactobacilli/acidity), the biological shift in flora is considered the hallmark change. 4. **Why Option D is Incorrect:** The acidic environment created by lactobacilli is bacteriostatic, actually **decreasing** the colonization of pathogenic bacteria. **NEET-PG High-Yield Pearls:** * **Chadwick’s Sign:** The bluish discoloration of the vagina due to increased vascularity (seen at 6–8 weeks). * **Osiander’s Sign:** Increased pulsation felt through the lateral fornices due to increased vascularity. * **Leukorrhea of Pregnancy:** The normal, thin, milky-white vaginal discharge resulting from increased exfoliation of epithelial cells and cervical mucus. * **Clinical Note:** The high glycogen content predisposes pregnant women to **Moniliasis (Candidiasis)**, despite the acidic pH.

Question 64: Combination of Doxylamine with which of the following is considered the safest antiemetic drug in pregnancy?

A. Palonosetron
B. Pyridoxine (Correct Answer)
C. Aprepitant
D. Domperidone

Explanation: **Explanation:** The combination of **Doxylamine (an H1-receptor antagonist) and Pyridoxine (Vitamin B6)** is recognized by the ACOG (American College of Obstetricians and Gynecologists) as the **first-line pharmacotherapy** for Nausea and Vomiting of Pregnancy (NVP) when conservative management fails. **Why Pyridoxine is Correct:** Pyridoxine is a water-soluble vitamin that plays a crucial role in amino acid metabolism. While its exact mechanism in reducing nausea is not fully understood, clinical trials have proven its efficacy and safety profile. The combination (formerly known as Diclegis/Bendectin) is the only FDA-approved medication specifically for NVP, categorized as **Category A** (safest) in pregnancy. **Analysis of Incorrect Options:** * **Palonosetron (A):** A second-generation 5-HT3 receptor antagonist. While Ondansetron is commonly used off-label, Palonosetron lacks extensive safety data in the first trimester. * **Aprepitant (C):** A substance P/neurokinin 1 (NK1) receptor antagonist used primarily for chemotherapy-induced nausea. It is not indicated for NVP. * **Domperidone (D):** A dopamine antagonist and prokinetic. It is generally avoided in the first trimester due to limited safety data and potential concerns regarding cardiac arrhythmias (QT prolongation). **High-Yield Clinical Pearls for NEET-PG:** * **First-line management of NVP:** Dietary modifications (small, frequent meals; ginger). * **First-line drug:** Pyridoxine monotherapy or Pyridoxine + Doxylamine. * **Hyperemesis Gravidarum (HG):** Defined by persistent vomiting, weight loss (>5%), and ketonuria. * **Wernicke’s Encephalopathy:** A rare but severe complication of HG due to **Thiamine (B1) deficiency**; always replenish Thiamine before giving IV glucose. * **Steroids:** Used as a last resort for refractory HG, but must be avoided before 10 weeks of gestation due to a potential risk of oral clefts.

Question 65: Human chorionic gonadotropin (hCG) can be estimated earliest by which method?

A. Radioimmunoassay (Correct Answer)
B. Enzyme-linked immunosorbent assay (ELISA)
C. Radioreceptor assay
D. Bioassay

Explanation: **Explanation:** **Why Radioimmunoassay (RIA) is the correct answer:** Radioimmunoassay is the most sensitive and specific method for detecting human chorionic gonadotropin (hCG). It utilizes the **beta-subunit (β-hCG)** principle, which prevents cross-reactivity with LH, FSH, and TSH. Due to its high sensitivity (detecting levels as low as 5 mIU/mL), it can identify hCG in maternal serum as early as **8 to 9 days after fertilization** (roughly 6 days before the missed period). This makes it the gold standard for the earliest possible detection of pregnancy. **Analysis of Incorrect Options:** * **Enzyme-linked immunosorbent assay (ELISA):** While widely used in modern clinical practice and "Home Pregnancy Tests" (Urine) due to speed and ease, it generally has a higher detection threshold than RIA. It typically becomes positive around the time of the missed period. * **Radioreceptor assay:** This method measures the biological activity of the hormone by its binding capacity to receptors. While sensitive, it cannot distinguish between hCG and LH, leading to lower specificity compared to RIA. * **Bioassay:** These are historical tests (e.g., Aschheim-Zondek, Friedman test) involving animal models. They are time-consuming, expensive, and lack the sensitivity required for early detection. **High-Yield Clinical Pearls for NEET-PG:** * **Doubling Time:** In a healthy intrauterine pregnancy, serum β-hCG levels double every **48 hours** during the first 8 weeks. * **Peak Levels:** hCG levels reach their peak at **8–10 weeks** (approx. 100,000 mIU/mL) and then decline to a plateau. * **Discriminatory Zone:** The level of hCG at which a gestational sac should be visible on TVS is **1500–2000 mIU/mL**. * **Source:** hCG is secreted by the **syncytiotrophoblast** cells of the developing placenta.

Question 66: In testicular feminisation syndrome, which of the following is true?

A. Buccal smear is chromatin positive
B. Normal breast size is observed (Correct Answer)
C. Menstruation is scanty and infrequent
D. Streak gonads are seen

Explanation: **Explanation:** **Testicular Feminization Syndrome**, now more commonly known as **Androgen Insensitivity Syndrome (AIS)**, is a condition where a genotypic male (46, XY) has a total or partial resistance to androgens. **Why Option B is correct:** In AIS, the testes produce normal or high levels of testosterone. However, because the androgen receptors are non-functional, this testosterone is peripherally converted into estrogen via the enzyme **aromatase**. This elevated estrogen, combined with the lack of androgenic opposition, leads to excellent **thelarche (breast development)**. In fact, these patients often have larger-than-average breasts compared to their female relatives, though the nipples/areolae may be pale and underdeveloped. **Analysis of Incorrect Options:** * **A. Buccal smear is chromatin positive:** Incorrect. The genotype is **46, XY**. A positive chromatin (Barr body) indicates the presence of two X chromosomes (found in 46, XX females or 47, XXY Klinefelter syndrome). * **C. Menstruation is scanty and infrequent:** Incorrect. There is **primary amenorrhea**. Because the testes produce **Anti-Müllerian Hormone (AMH)**, the uterus, fallopian tubes, and upper vagina fail to develop. There is no endometrium to shed. * **D. Streak gonads are seen:** Incorrect. Streak gonads are characteristic of Turner Syndrome (45, X) or Pure Gonadal Dysgenesis (Swyer Syndrome). In AIS, the patients have **functioning testes**, usually located intra-abdominally, in the inguinal canal, or labia majora. **High-Yield Clinical Pearls for NEET-PG:** * **Phenotype:** Phenotypically female with a blind-ending vaginal pouch. * **Hair:** Characteristically **absent or scanty** axillary and pubic hair (due to androgen resistance). * **Malignancy Risk:** There is a 2-5% risk of **Gonadoblastoma/Dysgerminoma** in the undescended testes; therefore, gonadectomy is recommended after puberty (to allow for natural breast development). * **Differential:** Differentiate from **Müllerian Agenesis (MRKH)**: MRKH has a 46, XX karyotype, normal pubic hair, and normal ovaries.

Question 67: Which of the following can be used in the management of cystitis in pregnancy, except?

A. Amoxicillin 500 mg every 8-12 hours for 3-7 days
B. Cephalexin 500 mg every 6-12 hours for 3-7 days
C. Nitrofurantoin 100 mg every 12 hours for 5-7 days
D. Cefpodoxime 400 mg every 12 hours (Correct Answer)

Explanation: **Explanation:** The management of acute cystitis in pregnancy requires antibiotics that are both safe for the fetus and effective against common uropathogens (primarily *E. coli*). **Why Option D is the correct answer:** The dosage provided for **Cefpodoxime (400 mg every 12 hours)** is incorrect. The standard therapeutic dose for treating cystitis in pregnancy is **100 mg every 12 hours** for 3–7 days. A 400 mg dose is excessively high for this indication and does not align with established obstetric guidelines (ACOG/IDSA). **Analysis of Incorrect Options:** * **Option A (Amoxicillin):** While resistance rates are increasing, Amoxicillin (500 mg 8–12 hourly) remains a Category B drug and is safe for use in pregnancy if the organism is susceptible. * **Option B (Cephalexin):** First-generation cephalosporins are a mainstay of treatment. The dose of 500 mg every 6–12 hours is standard and safe. * **Option C (Nitrofurantoin):** This is a first-line agent for cystitis. The 100 mg BD dose for 5–7 days is highly effective as it achieves high urinary concentrations. (Note: It should be avoided at term/during labor due to the risk of neonatal hemolytic anemia/G6PD deficiency). **High-Yield Clinical Pearls for NEET-PG:** * **Asymptomatic Bacteriuria (ASB):** Must always be treated in pregnancy (even if the patient has no symptoms) to prevent progression to pyelonephritis (20-30% risk if untreated). * **Drugs to Avoid:** * **Fluoroquinolones:** Risk of fetal cartilage damage. * **Trimethoprim:** Avoid in the 1st trimester (folate antagonist; neural tube defects). * **Sulfonamides:** Avoid in the 3rd trimester (risk of kernicterus). * **Test of Cure:** Always perform a follow-up urine culture 1–2 weeks after completing treatment in pregnant patients.

Question 68: What is the earliest time to detect human placental lactogen (hPL) in maternal serum?

A. 3 weeks (Correct Answer)
B. 12 weeks
C. 24 weeks
D. 28 weeks

Explanation: **Explanation:** **Human Placental Lactogen (hPL)**, also known as human chorionic somatomammotropin (hCS), is a polypeptide hormone produced by the **syncytiotrophoblast** of the placenta. 1. **Why 3 weeks is correct:** hPL can be detected in maternal serum as early as **3 weeks post-fertilization** (approximately 5 weeks after the Last Menstrual Period). Its concentration rises steadily throughout pregnancy, paralleling the increase in placental mass, and reaches its peak near term (36–37 weeks). 2. **Why other options are incorrect:** * **12 weeks:** While hPL levels are easily measurable by the end of the first trimester, this is not the *earliest* detection point. * **24 & 28 weeks:** These represent periods of significant metabolic demand where hPL levels are high, but they occur long after the hormone first enters the maternal circulation. **High-Yield Clinical Pearls for NEET-PG:** * **Function:** hPL is a potent **"diabetogenic"** hormone. It antagonizes insulin action, leading to maternal lipolysis (releasing free fatty acids) and decreased glucose utilization. This ensures a steady supply of glucose for the fetus. * **Structure:** It is structurally and immunologically similar to **Growth Hormone (GH)** and **Prolactin**. * **Clinical Marker:** Because its level is directly proportional to placental weight, it was historically used as a marker for placental function (though now largely replaced by biophysical profiles). * **Disappearance:** It has a very short half-life (15–30 minutes) and disappears from maternal blood within hours of delivery.

Question 69: In early pregnancy, what is the typical doubling time of hCG concentrations in plasma?

A. 12 hours
B. 48 hours (Correct Answer)
C. 72 hours
D. 96 hours

Explanation: ### Explanation **Correct Option: B (48 hours)** Human Chorionic Gonadotropin (hCG) is a glycoprotein hormone produced by the syncytiotrophoblast. In a normal intrauterine pregnancy, serum hCG levels rise exponentially during the first trimester. The "doubling time" is a critical clinical marker used to assess pregnancy viability. In approximately 85% of viable early pregnancies, the hCG concentration increases by at least 66% every 48 hours, typically doubling every **1.5 to 2 days (48 hours)**. This rapid rise continues until it peaks at around 8–11 weeks of gestation (approximately 100,000 mIU/mL). **Analysis of Incorrect Options:** * **A (12 hours):** This is physiologically too rapid. Such an accelerated rise is not seen in normal human gestation. * **C & D (72–96 hours):** While the doubling time slows down as pregnancy progresses (taking about 3 days at 6–7 weeks and 4 days by 8 weeks), the *typical* doubling time used for clinical assessment in early pregnancy (before 6 weeks) is 48 hours. A rise slower than this often suggests an abnormal pregnancy (e.g., ectopic pregnancy or impending miscarriage). **High-Yield Clinical Pearls for NEET-PG:** * **Discriminatory Zone:** This is the hCG level above which a gestational sac should be visible on ultrasound. For Transvaginal Sonography (TVS), it is typically **1,500–2,000 mIU/mL**. * **Ectopic Pregnancy:** Suspect this if hCG levels rise sub-optimally (less than 66% in 48 hours) or plateau. * **Molar Pregnancy:** Characterized by abnormally high hCG levels (often >100,000 mIU/mL) for the calculated gestational age. * **Structure:** hCG shares a common **alpha (α) subunit** with LH, FSH, and TSH; its specificity is derived from the **beta (β) subunit**.

Question 70: Which hormone's level remains unchanged during pregnancy?

A. Prolactin
B. Growth hormone
C. ACTH
D. Plasma vasopressin (Correct Answer)

Explanation: **Explanation:** The correct answer is **Plasma vasopressin (ADH)**. During pregnancy, the maternal body undergoes significant physiological adaptations, but the basal plasma concentration of vasopressin remains essentially **unchanged**. While the absolute levels of vasopressin do not change, the **osmotic threshold** for its release and the threshold for thirst are "reset" to a lower level (osmostat reset). This allows the body to maintain a new state of relative hypoosmolality (a drop of ~10 mOsm/kg) as normal during pregnancy. Additionally, the metabolic clearance of vasopressin increases significantly due to the production of **vasopressinase** by the placenta, but the pituitary compensates by increasing secretion, keeping the net plasma levels stable. **Why the other options are incorrect:** * **Prolactin:** Levels rise progressively (up to 10-fold) throughout pregnancy due to estrogenic stimulation of the maternal pituitary gland, preparing the breasts for lactation. * **Growth Hormone (GH):** While pituitary GH secretion decreases after the first trimester, **Placental Growth Hormone (hPGH)** rises significantly, becoming the dominant GH variant in maternal circulation by the second trimester. * **ACTH:** Maternal plasma ACTH levels rise steadily during pregnancy. This is driven by the placental production of CRH (Corticotropin-Releasing Hormone), which is refractory to feedback inhibition by cortisol. **NEET-PG High-Yield Pearls:** * **hCG:** Peaks at 8–10 weeks of gestation. * **hPL (Human Placental Lactogen):** Levels are directly proportional to placental mass; it is the primary hormone responsible for the "diabetogenic state" of pregnancy. * **Thyroid:** Total T3 and T4 increase (due to increased TBG), but **Free T3 and T4** remain relatively constant (or show a slight, transient rise in the first trimester due to hCG's weak TSH-like action).

Practice by Chapter

Endocrine Changes in Normal Pregnancy

Practice Questions

Thyroid Disorders in Pregnancy

Practice Questions

Diabetes in Pregnancy

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Adrenal Disorders in Pregnancy

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Pituitary Disorders in Pregnancy

Practice Questions

Hyperemesis Gravidarum

Practice Questions

Hormonal Regulation of Labor

Practice Questions

Pharmacokinetics of Hormones in Pregnancy

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Fetal Endocrine Development

Practice Questions

Placental Hormones

Practice Questions

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