Endocrinology of Pregnancy — MCQs

Endocrinology of Pregnancy Indian Medical PG Practice Questions and MCQs

Question 51: Which of the following is the source of HCG in a pregnant female?

A. Syncytiotrophoblast (Correct Answer)
B. Cytotrophoblast
C. Langhans layer
D. Chorionic villi

Explanation: **Explanation:** Human Chorionic Gonadotropin (hCG) is a glycoprotein hormone essential for maintaining the corpus luteum during early pregnancy. **1. Why Syncytiotrophoblast is correct:** The **syncytiotrophoblast** is the outer, multi-nucleated layer of the trophoblast that invades the uterine wall. It is the functional endocrine unit of the placenta. It synthesizes and secretes not only **hCG** but also Human Placental Lactogen (hPL), estrogen, and progesterone. hCG production begins as early as 6–8 days after fertilization (around the time of implantation). **2. Why the other options are incorrect:** * **Cytotrophoblast:** This is the inner, single-cell layer (the "stem cell" layer) of the trophoblast. While it provides the cells that fuse to form the syncytiotrophoblast, its primary endocrine product is **GnRH**, which locally stimulates the syncytiotrophoblast to produce hCG. * **Langhans layer:** This is simply another name for the **Cytotrophoblast**. In NEET-PG, remember that the Langhans layer tends to thin out after the 20th week of gestation. * **Chorionic villi:** This is a structural term referring to the finger-like projections of the placenta. While the villi contain both cytotrophoblasts and syncytiotrophoblasts, the specific cellular source of the hormone is the syncytiotrophoblast. **Clinical Pearls for NEET-PG:** * **Doubling Time:** In a healthy pregnancy, hCG levels double every **48–72 hours**. * **Peak Levels:** hCG levels reach their peak at **8–10 weeks** (approx. 100,000 mIU/mL) and then decline to a plateau. * **Subunits:** hCG has an $\alpha$ and $\beta$ subunit. The **$\alpha$-subunit** is identical to LH, FSH, and TSH; the **$\beta$-subunit** is unique and is what pregnancy tests detect. * **Thyroid Connection:** High levels of hCG (as seen in molar pregnancies) can cause hyperthyroidism because the $\alpha$-subunit can cross-react with TSH receptors.

Question 52: What is the diagnosis of imminent ovulation?

A. Endometrial biopsy
B. Pain
C. Temperature change
D. LH surge (Correct Answer)

Explanation: **Explanation:** The diagnosis of **imminent ovulation** (ovulation about to occur) is best confirmed by detecting the **LH surge**. 1. **Why LH surge is correct:** The LH surge is the most reliable predictor of impending ovulation. Triggered by a peak in estradiol levels (positive feedback), the surge initiates the final maturation of the oocyte and the weakening of the follicular wall. Ovulation typically occurs **24–36 hours after the onset** of the LH surge and **10–12 hours after its peak**. This is the physiological basis for over-the-counter ovulation predictor kits. 2. **Why other options are incorrect:** * **Endometrial biopsy:** This is a retrospective method. It identifies a secretory endometrium, which confirms that ovulation *has already occurred* (due to progesterone influence), rather than predicting it. * **Pain (Mittelschmerz):** While some women experience mid-cycle pelvic pain, it is subjective, inconsistent, and not a definitive diagnostic marker for the exact timing of ovulation. * **Temperature change:** The Basal Body Temperature (BBT) rises by 0.5–1.0°F *after* ovulation has occurred due to the thermogenic effect of progesterone. Like the biopsy, it is a retrospective indicator. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard for Ovulation Monitoring:** Serial Transvaginal Ultrasound (TVUS) to track follicular disappearance and the appearance of free fluid in the Pouch of Douglas. * **Best biochemical marker for "Confirmation" of ovulation:** Serum Progesterone levels >3 ng/ml (measured on Day 21 of a 28-day cycle). * **Cervical Mucus:** Under estrogen influence just before ovulation, the mucus becomes thin, watery, and shows **Spinnbarkeit** (high elasticity) and **Ferning** on microscopy.

Question 53: Which of the following is NOT true about diabetes in pregnancy?

A. Glucose challenge test is done between 24-28 weeks.
B. 50 gm of glucose is given for the screening test.
C. Insulin resistance decreases with pregnancy. (Correct Answer)
D. Diabetes control before conception is important to prevent malformations.

Explanation: ### Explanation **1. Why Option C is the Correct Answer (The Concept):** Pregnancy is a **diabetogenic state**. Contrary to the statement, **insulin resistance increases** during pregnancy, particularly in the second and third trimesters. This is a physiological adaptation to ensure a continuous supply of glucose to the fetus. The primary driver of this resistance is **Human Placental Lactogen (hPL)**, also known as Human Chorionic Somatomammotropin (hCS). Other contributing hormones include placental growth hormone, cortisol, progesterone, and prolactin. To compensate, the maternal pancreas must increase insulin secretion; failure to do so results in Gestational Diabetes Mellitus (GDM). **2. Analysis of Incorrect Options:** * **Option A & B:** The **Glucose Challenge Test (GCT)** is the standard screening tool. It involves giving **50g of oral glucose** regardless of the last meal. It is ideally performed between **24–28 weeks** because this is when insulin resistance (mediated by hPL) peaks. * **Option D:** Hyperglycemia during the period of organogenesis (first 8 weeks) is **teratogenic**. Pre-conception control (aiming for HbA1c < 6.5%) is crucial to reduce the risk of congenital malformations, most notably **Sacral Agenesis** (the most specific) and **Congenital Heart Defects** (the most common, specifically VSD and Transposition of Great Arteries). **3. High-Yield Clinical Pearls for NEET-PG:** * **DIPSI Criteria:** A single-step test using 75g glucose; GDM is diagnosed if 2-hour plasma glucose is **≥ 140 mg/dL**. * **Fetal Complication:** The most common cause of neonatal death in diabetic mothers is **Respiratory Distress Syndrome (RDS)** (hyperinsulinemia inhibits surfactant production). * **Drug of Choice:** **Insulin** remains the gold standard. Among oral hypoglycemics, Metformin and Glibenclamide are sometimes used but are not first-line in all guidelines. * **Macrosomia:** Defined as birth weight > 4kg or > 4.5kg; caused by fetal hyperinsulinemia (growth-promoting effect).

Question 54: At which week of gestation is human chorionic gonadotropin (HCG) production maximal?

A. 6-8 weeks
B. 8-10 weeks
C. 10-12 weeks (Correct Answer)
D. 14-16 weeks

Explanation: **Explanation:** Human Chorionic Gonadotropin (hCG) is a glycoprotein hormone produced by the **syncytiotrophoblast** of the developing placenta. Its primary physiological role is to maintain the corpus luteum, ensuring the continued secretion of progesterone until the placenta takes over steroidogenesis (the luteo-placental shift). **Why 10-12 weeks is correct:** hCG levels become detectable in maternal serum approximately 8–9 days after ovulation (shortly after implantation). The levels rise exponentially, doubling every 48–72 hours. Peak concentration is reached between **10 and 12 weeks of gestation** (specifically around 70–90 days). After this peak, levels decline significantly to a lower plateau which is maintained for the remainder of the pregnancy. **Analysis of Incorrect Options:** * **A (6-8 weeks):** While hCG is rising rapidly during this period, it has not yet reached its physiological zenith. * **B (8-10 weeks):** Some texts suggest the rise begins to slow here, but the absolute peak is generally cited closer to the end of the first trimester (10-12 weeks). * **D (14-16 weeks):** By this stage, the placenta is fully functional (luteo-placental shift is complete), and hCG levels have already begun their decline to a steady state. **High-Yield Clinical Pearls for NEET-PG:** * **Structure:** hCG shares a common **alpha (α) subunit** with LH, FSH, and TSH. Specificity is determined by the **beta (β) subunit**. * **Doubling Time:** In a healthy intrauterine pregnancy, β-hCG levels should increase by at least 66% every 48 hours. * **Abnormal Levels:** * **Higher than expected:** Multiple pregnancy, Molar pregnancy (Hydatidiform mole), or Down Syndrome (Trisomy 21). * **Lower than expected:** Ectopic pregnancy or threatened/spontaneous abortion. * **Nadir:** The lowest level after the peak is reached at approximately 20 weeks.

Question 55: Which of the following hormonal changes are typically observed in Polycystic Ovary Syndrome (PCOS)? (i) Luteinizing hormone (LH) is elevated (ii) Total free estrone is decreased (iii) Insulin is elevated (iv) Sex hormone-binding globulin (SHBG) is increased (v) Progesterone is decreased

A. False, False, True, True, False
B. True, False, True, False, True (Correct Answer)
C. True, True, True, False, True
D. False, True, True, False, True

Explanation: ### Explanation: Endocrinology of PCOS Polycystic Ovary Syndrome (PCOS) is characterized by a complex interplay of hyperandrogenism, insulin resistance, and chronic anovulation. **1. Analysis of Hormonal Changes:** * **(i) LH is elevated (True):** There is an increased frequency and amplitude of GnRH pulses, leading to high LH levels. The **LH:FSH ratio** is typically >2:1 or 3:1. * **(ii) Total free estrone is decreased (False):** In PCOS, peripheral aromatization of androstenedione in adipose tissue leads to **increased** levels of estrone (E1). This "unopposed estrogen" increases the risk of endometrial hyperplasia. * **(iii) Insulin is elevated (True):** Peripheral insulin resistance leads to compensatory **hyperinsulinemia**. Insulin acts synergistically with LH to increase androgen production from thecal cells and suppresses SHBG production in the liver. * **(iv) SHBG is increased (False):** High levels of insulin and androgens **decrease** the hepatic synthesis of SHBG. Lower SHBG results in higher levels of **free (biologically active) testosterone**. * **(v) Progesterone is decreased (True):** Due to chronic anovulation, no corpus luteum is formed, leading to a deficiency in progesterone. **2. Why Option B is Correct:** It accurately reflects the pathophysiology: High LH and Insulin, Low SHBG and Progesterone, and High (not low) Estrone. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard for Diagnosis:** Rotterdam Criteria (requires 2 out of 3: Oligo/anovulation, Clinical/Biochemical Hyperandrogenism, Polycystic ovaries on USG). * **The "Vicious Cycle":** Hyperinsulinemia → ↓ SHBG → ↑ Free Androgens → Peripheral Aromatization → ↑ Estrone → Pituitary sensitization to GnRH → ↑ LH. * **Drug of Choice for Ovulation Induction:** Letrozole (Aromatase inhibitor) is now preferred over Clomiphene Citrate. * **Metabolic Risk:** PCOS patients have a higher risk of Type 2 Diabetes and Endometrial Carcinoma.

Question 56: Which of the following is true about human chorionic gonadotropin (hCG)?

A. Produced by cytotrophoblast
B. Prevents involution of the corpus luteum (Correct Answer)
C. Reaches maximum levels at 20 weeks of pregnancy
D. Secretion starts 2 days after ovulation

Explanation: **Explanation:** **Human Chorionic Gonadotropin (hCG)** is a glycoprotein hormone essential for the maintenance of early pregnancy. It is a heterodimer consisting of an $\alpha$-subunit (identical to LH, FSH, and TSH) and a $\beta$-subunit (unique to hCG). **Why Option B is Correct:** The primary biological function of hCG in early pregnancy is its **luteotropic effect**. It acts on the LH receptors of the **corpus luteum**, "rescuing" it from programmed involution. This ensures the continued production of **progesterone**, which is vital for maintaining the decidua and preventing menstruation until the placenta takes over steroidogenesis (the luteal-placental shift) at around 7–9 weeks. **Analysis of Incorrect Options:** * **Option A:** hCG is produced by the **syncytiotrophoblast**, not the cytotrophoblast. The cytotrophoblast acts as the stem cell layer that differentiates into the syncytiotrophoblast. * **Option C:** hCG levels do not peak at 20 weeks. They reach **maximum levels (approx. 100,000 mIU/mL) at 8–10 weeks** (60–70 days) of gestation, after which they decline to a lower steady state by 20 weeks. * **Option D:** Secretion does not start 2 days after ovulation. hCG is secreted only after **implantation**, which occurs roughly 6–9 days after fertilization (approx. day 21–24 of the cycle). It becomes detectable in maternal serum around day 8–9 post-fertilization. **High-Yield Clinical Pearls for NEET-PG:** * **Doubling Time:** In a healthy pregnancy, serum hCG levels double every **48 hours** during the first 8 weeks. * **Hyperemesis Gravidarum:** Associated with peak hCG levels (8–10 weeks) and conditions like molar pregnancy or multiple gestations. * **Thyroid Stimulating Effect:** Due to structural similarity with TSH, very high hCG levels can cause **gestational transient thyrotoxicosis**. * **Down Syndrome:** hCG is **increased** in the second-trimester quadruple screen for Trisomy 21.

Question 57: A 24-year-old woman with chronic hypothyroidism, currently well-controlled on 75 micrograms of thyroxine, wishes to conceive. She does not smoke, drink, or have any other medical ailments. What is the best advice regarding her thyroxine medication during pregnancy?

A. Stop taking thyroxine and switch to methimazole.
B. Thyroxine is safe during pregnancy but not essential to continue.
C. Thyroxine is not safe during pregnancy; it is better for the baby to be hypothyroid than hyperthyroid.
D. Thyroxine is safe in pregnancy, and the dose will likely need to be increased to avoid hypothyroidism, which can adversely affect the baby. (Correct Answer)

Explanation: **Explanation:** **1. Why Option D is Correct:** During pregnancy, the demand for thyroid hormone increases significantly (by approximately **30–50%**). This is due to several physiological factors: * **Estrogen-induced increase in Thyroid Binding Globulin (TBG):** Higher TBG levels increase the pool of bound (inactive) T4, necessitating more production to maintain free T4 levels. * **hCG Stimulation:** hCG acts as a weak TSH agonist, stimulating the thyroid. * **Placental Metabolism:** The placenta contains deiodinases that break down T4. * **Fetal Needs:** The fetus relies entirely on maternal T4 for neurodevelopment until its own thyroid begins functioning at **12 weeks**. Untreated maternal hypothyroidism is linked to lower IQ, neurocognitive deficits, and increased risk of miscarriage or preterm birth. **2. Why Other Options are Incorrect:** * **Option A:** Methimazole is an anti-thyroid drug used for *hyperthyroidism*. It is contraindicated in the first trimester due to teratogenicity (aplasia cutis, choanal atresia). * **Option B:** Thyroxine is absolutely essential. Maternal hypothyroidism increases the risk of pre-eclampsia, placental abruption, and fetal growth restriction. * **Option C:** Thyroxine (T4) is a Category A drug and is safe. Fetal hypothyroidism is never "better"; it leads to congenital hypothyroidism (Cretinism). **3. NEET-PG High-Yield Pearls:** * **Dose Adjustment:** Patients should increase their dose by **25–30%** (or add 2 extra tablets per week) as soon as pregnancy is confirmed. * **Monitoring:** Check TSH every **4 weeks** during the first half of pregnancy. * **Target TSH:** Aim for the lower half of the trimester-specific reference range (generally **<2.5 mIU/L**). * **Interaction:** Iron and Calcium supplements (common in pregnancy) interfere with thyroxine absorption; they must be taken at least 4 hours apart.

Question 58: A girl presents with primary amenorrhea, normal breast development, hirsutism, and acne. What is the most probable diagnosis?

A. Klinefelter syndrome
B. Polycystic Ovarian Disease (PCOD) (Correct Answer)
C. Turner's syndrome
D. Gonadal dysgenesis

Explanation: ### Explanation The clinical presentation of **primary amenorrhea** combined with **normal breast development** and signs of **hyperandrogenism** (hirsutism and acne) is a classic indicator of Polycystic Ovarian Disease (PCOD/PCOS). **1. Why PCOD is the Correct Answer:** In PCOD, the hypothalamic-pituitary-ovarian axis is functional, leading to adequate estrogen production and **normal breast development** (Tanner Stage 5). However, an imbalance in LH/FSH ratios and insulin resistance leads to excess ovarian androgen production. This hyperandrogenism causes **hirsutism and acne**. While PCOD typically presents as secondary amenorrhea, it is a recognized cause of primary amenorrhea in roughly 5-10% of cases where the hormonal imbalance occurs at the onset of puberty. **2. Why Other Options are Incorrect:** * **Klinefelter Syndrome (47, XXY):** This occurs in phenotypic males. They present with small testes, gynecomastia, and infertility, not primary amenorrhea. * **Turner’s Syndrome (45, XO):** These patients typically have **streak ovaries** (estrogen deficiency), resulting in **absent/poor breast development** and short stature. Hyperandrogenism is not a feature. * **Gonadal Dysgenesis:** Similar to Turner’s, there is a failure of ovarian development. Without estrogen, there is no breast development (sexual infantilism). **3. High-Yield Clinical Pearls for NEET-PG:** * **Rotterdam Criteria for PCOS:** Requires 2 out of 3: (1) Oligo/anovulation, (2) Clinical/biochemical hyperandrogenism, (3) Polycystic ovaries on ultrasound. * **LH:FSH Ratio:** Often >2:1 or 3:1 in PCOS. * **Differential for Primary Amenorrhea with Normal Breasts:** Always consider PCOD, Mullerian Agenesis (MRKH), and Androgen Insensitivity Syndrome (AIS). The presence of hirsutism specifically points toward PCOD or Adrenal Hyperplasia.

Question 59: Which of the following statements is FALSE regarding the endocrine changes in a normal pregnancy?

A. There is a fall in free T4/T3 levels during the third trimester.
B. Thyroid-stimulating hormone (TSH) falls in the first and second trimesters but increases in the third trimester.
C. TSH rises in the first and second trimesters but falls in the third trimester. (Correct Answer)
D. There is an increase in Thyroid Binding Globulin (TBG).

Explanation: In a normal pregnancy, the thyroid gland undergoes significant physiological changes to meet increased metabolic demands. **Why Option C is the Correct Answer (The False Statement):** The statement is incorrect because **TSH levels actually fall** during the first trimester. This occurs because Human Chorionic Gonadotropin (hCG) shares a common alpha-subunit with TSH. Due to this structural similarity, high levels of hCG in early pregnancy exert a "TSH-like" effect on the thyroid gland, stimulating thyroid hormone production. Through negative feedback, this leads to a transient **suppression of pituitary TSH**. As hCG levels decline in the second and third trimesters, TSH levels gradually rise back toward pre-pregnancy baselines. **Analysis of Other Options:** * **Option A:** Free T4 and T3 levels typically show a slight, progressive decline in the second and third trimesters, often reaching the lower end of the normal range. * **Option B:** This correctly describes the TSH trend: a decrease in the first trimester (due to hCG peak) followed by a gradual increase in the third trimester. * **Option C:** Estrogen stimulates the liver to increase the production of **Thyroid Binding Globulin (TBG)**. This leads to an increase in *Total* T3 and T4 levels, though the *free* (active) hormone levels remain within narrow physiological limits. **High-Yield NEET-PG Pearls:** 1. **hCG and TSH:** hCG is a weak thyroid stimulator. Peak hCG (at 10–12 weeks) corresponds to the lowest TSH levels. 2. **Total vs. Free Hormones:** Total T3/T4 increase (due to TBG), but Free T3/T4 remain relatively stable or slightly decrease. 3. **Iodine Requirement:** Pregnancy is a state of relative iodine deficiency due to increased glomerular filtration and fetal transfer; hence, iodine requirements increase. 4. **Goiter:** A mild increase in thyroid size (10–15%) is physiological, but a visible goiter is always pathological.

Question 60: Fertilization typically takes place how long after ovulation?

A. 1-2 days (Correct Answer)
B. 5-6 days
C. 8-12 days
D. More than 12 days

Explanation: **Explanation:** **1. Why Option A is Correct:** Fertilization occurs when a sperm penetrates a mature oocyte. The biological window for this event is strictly governed by the lifespan of the gametes. Following ovulation, the secondary oocyte remains viable and capable of being fertilized for only **12 to 24 hours**. While sperm can survive in the female reproductive tract for 3–5 days, the oocyte's short functional life necessitates that fertilization occurs within **1–2 days** (24–48 hours) of ovulation. This typically takes place in the **ampulla** of the fallopian tube. **2. Why the Other Options are Incorrect:** * **Option B (5-6 days):** By this time, an unfertilized oocyte has already degenerated. However, this timeframe is significant for a different reason: a fertilized embryo (blastocyst) typically reaches the uterine cavity and begins **implantation** 5–7 days after fertilization. * **Option C (8-12 days):** This period corresponds to the completion of implantation and the start of detectable hCG production. * **Option D (>12 days):** This coincides with the expected date of the next menstrual period. If fertilization hasn't occurred within the first 24 hours post-ovulation, the corpus luteum will eventually regress, leading to menstruation. **3. NEET-PG Clinical Pearls:** * **Site of Fertilization:** Ampulla of the fallopian tube (most common site). * **Sperm Capacitation:** Takes roughly 7 hours; must occur in the female reproductive tract before the sperm can fertilize the egg. * **Cortical Reaction:** The mechanism that prevents polyspermy once the first sperm penetrates the oocyte. * **Zygote Transport:** It takes approximately 3–4 days for the zygote to travel through the fallopian tube to the uterus.

Practice by Chapter

Endocrine Changes in Normal Pregnancy

Practice Questions

Thyroid Disorders in Pregnancy

Practice Questions

Diabetes in Pregnancy

Practice Questions

Adrenal Disorders in Pregnancy

Practice Questions

Pituitary Disorders in Pregnancy

Practice Questions

Hyperemesis Gravidarum

Practice Questions

Hormonal Regulation of Labor

Practice Questions

Pharmacokinetics of Hormones in Pregnancy

Practice Questions

Fetal Endocrine Development

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Placental Hormones

Practice Questions

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