Endocrinology of Pregnancy — MCQs

Urine screening of an apparently healthy pregnant woman demonstrates a positive Clinitest reaction. Blood glucose levels were within normal limits, and more specific testing for urine glucose is negative. The woman has been unaware of any metabolic problems and has been living a normal life. Deficiency of which of the following enzymes would most likely produce this presentation?

Q196Easy

True about hCG is:

Q197Medium

What is the rapid method for chromosome identification in intersex individuals?

Q198Medium

Carbimazole is associated with which of the following conditions, except?

Q199Easy

What is the percentage increase seen in plasma volume during pregnancy?

Q200Medium

Which of the following statements about hCG is FALSE?

Endocrinology of Pregnancy Indian Medical PG Practice Questions and MCQs

Question 191: Which hormone has the greatest production rate near term in humans, approximately 1 gram per day?

A. Relaxin
B. Progesterone
C. hCG
D. hPL (Correct Answer)

Explanation: **Explanation:** The correct answer is **hPL (Human Placental Lactogen)**, also known as Human Chorionic Somatomammotropin (hCS). **1. Why hPL is correct:** hPL is produced by the syncytiotrophoblast of the placenta. Its production is directly proportional to the placental mass. Near term, hPL has the **highest production rate of any known hormone in humans**, reaching approximately **1 gram per day**. Its primary physiological role is to act as an "anti-insulin" agent (diabetogenic effect), increasing maternal insulin resistance to ensure a steady supply of glucose for fetal growth. **2. Why the other options are incorrect:** * **Progesterone (B):** While progesterone levels rise significantly during pregnancy to maintain uterine quiescence, its production rate near term is approximately **250–300 mg per day**, which is significantly less than the 1000 mg (1g) produced by hPL. * **hCG (C):** Human Chorionic Gonadotropin peaks early in pregnancy (around 8–10 weeks) and then declines to a lower plateau. It is measured in International Units (IU), and its mass production is nowhere near the gram level. * **Relaxin (A):** Produced by the corpus luteum and placenta, relaxin is involved in softening the cervix and pelvic ligaments. It circulates in picogram or nanogram concentrations. **3. NEET-PG High-Yield Pearls:** * **hPL** is the most important hormone responsible for the **diabetogenic state** of pregnancy. * It is structurally similar to **Growth Hormone** and **Prolactin**. * Low levels of hPL are associated with **Placental Insufficiency** and Fetal Growth Restriction (FGR). * **Half-life:** hPL has a very short half-life (approx. 15–30 minutes), making it a potential (though now rarely used) marker for placental function.

Question 192: Which of the following drugs is used in the management of thyroid storm during pregnancy?

A. Sodium iodide
B. Dexamethasone
C. Propranolol
D. All of the above (Correct Answer)

Explanation: **Explanation:** Thyroid storm is a life-threatening medical emergency characterized by extreme hypermetabolism. In pregnancy, management requires a multi-modal approach to block the synthesis, release, and peripheral conversion of thyroid hormones, while also managing systemic symptoms. **Why "All of the above" is correct:** The management of thyroid storm follows a specific pharmacological sequence, and all listed drugs play a vital role: 1. **Sodium Iodide (Option A):** Administered at least one hour after starting antithyroid drugs (PTU/Methimazole). It inhibits the release of preformed thyroid hormones from the gland (the **Wolff-Chaikoff effect**). 2. **Dexamethasone (Option B):** Corticosteroids serve two purposes: they inhibit the peripheral conversion of $T_4$ to the more active $T_3$ and protect against relative adrenal insufficiency associated with severe thyrotoxicosis. 3. **Propranolol (Option C):** This beta-blocker is essential to control the life-threatening cardiovascular symptoms (tachycardia, palpitations, and arrhythmias) by antagonizing the effects of excess catecholamines. **Clinical Pearls for NEET-PG:** * **Drug of Choice (Antithyroid):** Propylthiouracil (PTU) is preferred over Methimazole in thyroid storm because PTU also inhibits the peripheral conversion of $T_4$ to $T_3$. * **Sequence Matters:** Always give PTU/Methimazole *before* Iodine to prevent the iodine from being used as a substrate for new hormone synthesis (Jod-Basedow effect). * **Fetal Safety:** While Propranolol is used acutely in a storm, chronic use in pregnancy is associated with Fetal Growth Restriction (FGR) and neonatal hypoglycemia. * **Diagnosis:** Thyroid storm is a clinical diagnosis (often using the **Burch-Wartofsky Point Scale**); do not wait for lab results to initiate treatment.

Question 193: What is the commonest cause of female pseudohermaphroditism?

A. Virilizing ovarian tumor
B. Ovarian dysgenesis
C. Exogenous androgen
D. Congenital adrenal hyperplasia (Correct Answer)

Explanation: **Explanation:** **Female Pseudohermaphroditism** (now categorized under 46, XX Disorders of Sex Development) is a condition where an individual has a female genotype (46, XX) and normal ovaries, but the external genitalia are virilized or ambiguous due to excessive androgen exposure in utero. **Why Congenital Adrenal Hyperplasia (CAH) is the correct answer:** CAH is the **most common cause** of female pseudohermaphroditism, accounting for approximately 90-95% of cases. It is an autosomal recessive disorder, most frequently caused by a **21-hydroxylase deficiency**. This enzyme defect impairs cortisol synthesis, leading to an overproduction of Adrenocorticotropic Hormone (ACTH). The resulting adrenal hyperplasia causes a massive "shunting" of steroid precursors into the androgen pathway, virilizing the female fetus. **Analysis of Incorrect Options:** * **A. Virilizing ovarian tumor:** While maternal tumors (like Arrhenoblastoma or Luteoma of pregnancy) can cause fetal virilization, they are extremely rare during pregnancy compared to the incidence of CAH. * **B. Ovarian dysgenesis:** This (e.g., Turner Syndrome) typically presents with streak gonads and female external genitalia, but lacks virilization. It is a cause of primary amenorrhea, not pseudohermaphroditism. * **C. Exogenous androgen:** Iatrogenic exposure (e.g., maternal intake of progestins or danazol) can cause virilization, but this is clinically rare due to modern pharmacological awareness. **High-Yield Clinical Pearls for NEET-PG:** * **Most common enzyme deficiency in CAH:** 21-hydroxylase deficiency (leads to high 17-OH Progesterone). * **Salt-wasting crisis:** Common in severe 21-hydroxylase deficiency due to aldosterone deficiency (Hyponatremia + Hyperkalemia). * **Prader Staging:** Used to describe the degree of virilization of external genitalia in these patients. * **Management:** Maternal administration of **Dexamethasone** (which crosses the placenta) can suppress the fetal ACTH and prevent virilization if started early in pregnancy.

Question 194: Which of the following medications can be safely used in pregnancy?

A. Propylthiouracil (Correct Answer)
B. Methotrexate
C. Warfarin
D. Tetracycline

Explanation: **Explanation:** **Correct Option: A. Propylthiouracil (PTU)** Propylthiouracil is the drug of choice for the management of hyperthyroidism in the **first trimester** of pregnancy. It is preferred over Methimazole during early organogenesis because it is more highly protein-bound, leading to less placental transfer. More importantly, it avoids the "Methimazole embryopathy" (Aplasia cutis, choanal atresia, and esophageal atresia). While PTU carries a risk of maternal hepatotoxicity, its safety profile regarding fetal structural malformations makes it the standard for early pregnancy. **Incorrect Options:** * **B. Methotrexate:** A potent folic acid antagonist and a known **teratogen**. It causes "Fetal Methotrexate Syndrome," characterized by craniofacial abnormalities, limb defects, and growth restriction. It is strictly contraindicated (Category X) unless used for medical management of ectopic pregnancy. * **C. Warfarin:** Crosses the placenta and causes **Fetal Warfarin Syndrome** (Stippled epiphyses, nasal hypoplasia, and CNS defects). It is typically replaced by Heparin (LMWH/UFH) in pregnancy, as Heparin does not cross the placenta. * **D. Tetracycline:** Known to cause permanent **yellow-brown discoloration of deciduous teeth** and inhibition of bone growth (skeletal hypoplasia) when used after the first trimester. **High-Yield Clinical Pearls for NEET-PG:** * **Switching Rule:** Use PTU in the 1st trimester; switch to Methimazole in the 2nd and 3rd trimesters to avoid PTU-induced maternal liver failure. * **Rule of Thumbs:** Most ACE inhibitors (Renal dysgenesis), Thalidomide (Phocomelia), and Isotretinoin (CNS/Ear/Heart defects) are high-yield "Never" drugs in pregnancy. * **Safe Alternatives:** For Hypertension, use Labetalol or Methyldopa; for Anticoagulation, use Heparin; for Diabetes, use Insulin.

Question 195: Urine screening of an apparently healthy pregnant woman demonstrates a positive Clinitest reaction. Blood glucose levels were within normal limits, and more specific testing for urine glucose is negative. The woman has been unaware of any metabolic problems and has been living a normal life. Deficiency of which of the following enzymes would most likely produce this presentation?

A. Fructokinase (Correct Answer)
B. Fructose 1-phosphate aldolase
C. Galactose 1-phosphate uridyl transferase
D. Lactase

Explanation: **Explanation:** The patient presents with **asymptomatic fructosuria**, a benign condition caused by a deficiency of **Fructokinase**. 1. **Why Fructokinase is correct:** Fructokinase is the first enzyme in fructose metabolism, converting fructose to fructose-1-phosphate. When deficient, fructose cannot be trapped in cells and accumulates in the blood and urine. Since fructose is a **reducing sugar**, it yields a **positive Clinitest** (which detects all reducing substances). However, because it is not glucose, the **glucose oxidase dipstick** (specific for glucose) remains **negative**. The condition is entirely asymptomatic and often discovered incidentally during routine pregnancy screening. 2. **Why other options are incorrect:** * **Fructose 1-phosphate aldolase (Aldolase B):** Deficiency causes **Hereditary Fructose Intolerance**. This is a severe condition presenting with hypoglycemia, jaundice, and vomiting after fructose ingestion. It is not asymptomatic. * **Galactose 1-phosphate uridyl transferase:** Deficiency causes **Classic Galactosemia**. This presents in infancy with cataracts, liver failure, and intellectual disability. It is not a benign finding in an otherwise healthy adult. * **Lactase:** Deficiency leads to lactose intolerance (diarrhea, bloating). While it involves sugars, it does not typically cause a positive Clinitest in urine as lactose is not absorbed to be excreted. **High-Yield Clinical Pearls for NEET-PG:** * **Clinitest vs. Dipstick:** Clinitest (Copper reduction) detects all reducing sugars (fructose, galactose, lactose). Dipstick is specific for glucose. * **Essential Fructosuria:** Autosomal recessive, asymptomatic, no treatment required. * **Reducing Sugars:** All monosaccharides (glucose, fructose, galactose) and some disaccharides (lactose, maltose) are reducing sugars. **Sucrose is NOT** a reducing sugar.

Question 196: True about hCG is:

A. Alpha subunit identical to LH, FSH and TSH (Correct Answer)
B. Causes involution of corpus luteum
C. Doubles in 7-10 days
D. Maximum level seen at 50 days of gestation

Explanation: **Explanation:** Human Chorionic Gonadotropin (hCG) is a glycoprotein hormone secreted by the syncytiotrophoblast. Understanding its structure and kinetics is high-yield for NEET-PG. **1. Why Option A is Correct:** hCG is a heterodimer consisting of two subunits: **Alpha (α) and Beta (β)**. The **α-subunit** is identical in amino acid sequence to the α-subunits of Luteinizing Hormone (LH), Follicle-Stimulating Hormone (FSH), and Thyroid-Stimulating Hormone (TSH). Biological specificity is determined solely by the **β-subunit**, which is why pregnancy tests specifically detect the β-hCG fraction to avoid cross-reactivity. **2. Why Other Options are Incorrect:** * **Option B:** hCG does not cause involution; rather, it **rescues and maintains** the corpus luteum, ensuring continued progesterone production until the luteo-placental shift (at 7–10 weeks). * **Option C:** In early pregnancy, hCG levels **double every 48 to 72 hours** (approx. 2 days), not 7–10 days. A slow rise or plateau is often indicative of an ectopic pregnancy or impending miscarriage. * **Option D:** hCG levels peak at **8–11 weeks (60–70 days)** of gestation, reaching approximately 100,000 mIU/mL, before declining to a lower steady state. **Clinical Pearls for NEET-PG:** * **Earliest Detection:** hCG can be detected in maternal serum **8–9 days after fertilization** (around the time of implantation). * **Thyroid Link:** Due to the identical α-subunit and structural similarity to TSH, very high levels of hCG (as seen in Molar pregnancy) can overstimulate the thyroid gland, leading to **gestational hyperthyroidism**. * **Discriminatory Zone:** The level of hCG at which a gestational sac should be visible on TVS is typically **1500–2000 mIU/mL**.

Question 197: What is the rapid method for chromosome identification in intersex individuals?

A. FISH (Correct Answer)
B. PCR
C. SSCP
D. Karyotyping

Explanation: **Explanation:** The correct answer is **FISH (Fluorescent In Situ Hybridization)**. In the management of intersex disorders (Disorders of Sex Development - DSD), rapid identification of chromosomal sex is critical for parental counseling and clinical decision-making. 1. **Why FISH is correct:** FISH uses fluorescently labeled DNA probes that bind to specific sequences on the X and Y chromosomes. It can be performed on **interphase nuclei** (non-dividing cells), meaning it does not require cell culture. This allows for a rapid turnaround time, typically **24 to 48 hours**, making it the fastest reliable method for identifying sex chromosomes in a clinical setting. 2. **Why other options are incorrect:** * **Karyotyping:** While it is the "Gold Standard" for definitive diagnosis, it requires cells to be in metaphase. This necessitates cell culture, which takes **7 to 14 days**, making it too slow for immediate rapid identification. * **PCR (Polymerase Chain Reaction):** While very fast at amplifying DNA sequences (like the SRY gene), it is generally used for targeted gene mutation analysis rather than comprehensive chromosome identification or detecting mosaicism. * **SSCP (Single Strand Conformation Polymorphism):** This is a technique used to detect small mutations or polymorphisms in DNA sequences; it is not used for chromosome identification. **Clinical Pearls for NEET-PG:** * **Gold Standard for Chromosomal Analysis:** Conventional G-banded Karyotyping. * **Rapid Sex Determination:** FISH (specifically looking for X and Y centromeric probes). * **Barr Body:** A quick but outdated screening method; it represents the inactive X chromosome. * **SRY Gene:** Located on the short arm of the Y chromosome; its presence is the primary determinant of male sexual differentiation.

Question 198: Carbimazole is associated with which of the following conditions, except?

A. Choanal atresia
B. Cleft lip and cleft palate (Correct Answer)
C. Scalp defect
D. Neck swelling

Explanation: **Explanation:** The question asks for the condition **not** typically associated with Carbimazole exposure during pregnancy. Carbimazole and its active metabolite, Methimazole, are associated with a specific pattern of fetal malformations known as **Methimazole Embryopathy**. **1. Why "Cleft lip and cleft palate" is the correct answer:** While cleft lip and palate are common congenital anomalies, they are **not** specifically linked to Carbimazole. They are more commonly associated with other teratogens like Phenytoin (Fetal Hydantoin Syndrome) or Topiramate. **2. Analysis of Incorrect Options (Associated with Carbimazole):** * **Scalp defect (Aplasia Cutis Congenita):** This is the most characteristic feature of Methimazole embryopathy. It involves the congenital absence of skin, most commonly on the scalp vertex. * **Choanal atresia:** Carbimazole exposure in the first trimester is a known risk factor for choanal atresia (narrowing/blockage of the nasal passage) and esophageal atresia. * **Neck swelling:** Carbimazole crosses the placenta and can inhibit the fetal thyroid gland, leading to **fetal hypothyroidism and goiter** (neck swelling). **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Due to the risk of Methimazole embryopathy, **Propylthiouracil (PTU)** is the preferred anti-thyroid drug in the **first trimester**. * **Switching:** Many clinicians switch from PTU to Methimazole/Carbimazole in the **second and third trimesters** to avoid PTU-induced maternal hepatotoxicity. * **Mechanism:** Carbimazole is a prodrug that is rapidly converted to Methimazole in the body. * **Other associations:** "Face" dysmorphism (broad nasal bridge) and gastrointestinal anomalies (omphalocele) are also part of the embryopathy spectrum.

Question 199: What is the percentage increase seen in plasma volume during pregnancy?

A. 10-20%
B. 20-30%
C. 30-40%
D. 40-50% (Correct Answer)

Explanation: **Explanation:** The correct answer is **40-50%**. During pregnancy, the maternal body undergoes significant cardiovascular adaptations to meet the metabolic demands of the fetus and protect the mother against blood loss during delivery. **Why 40-50% is correct:** Plasma volume begins to increase as early as the 6th week of gestation, reaching its peak around **32–34 weeks**. This expansion is driven by the activation of the Renin-Angiotensin-Aldosterone System (RAAS), leading to sodium and water retention. While plasma volume increases by approximately **40–50%** (roughly 1.25 liters), the Red Blood Cell (RBC) mass only increases by about **20–30%**. This disproportionate rise leads to **physiological anemia of pregnancy** due to hemodilution. **Why other options are incorrect:** * **A & B (10-30%):** These values are too low for plasma volume but roughly correspond to the increase in **RBC mass** (20-30%). * **C (30-40%):** While closer, this underestimates the total expansion seen in a singleton pregnancy, which typically reaches the 45-50% mark by the third trimester. **High-Yield Clinical Pearls for NEET-PG:** 1. **Cardiac Output:** Increases by **30–50%**, peaking at 20–24 weeks. 2. **Stroke Volume:** Increases by 25–30%. 3. **Multiple Gestation:** In twin pregnancies, the plasma volume increase is even higher (up to 70%). 4. **Uterine Blood Flow:** Increases from 50 mL/min (pre-pregnancy) to approximately **500–750 mL/min** at term. 5. **Blood Pressure:** Diastolic BP decreases in the first and second trimesters (nadir at 24 weeks) due to decreased systemic vascular resistance (SVR) mediated by progesterone and nitric oxide.

Question 200: Which of the following statements about hCG is FALSE?

A. hCG is a lipoprotein.
B. hCG can be detected by radioimmunoassay more than 6 days post-conception.
C. hCG is secreted by the corpus luteum.
D. hCG has a non-specific alpha subunit and a specific beta subunit. (Correct Answer)

Explanation: ### Explanation **1. Understanding the Correct Answer (Option D)** Human Chorionic Gonadotropin (hCG) is a **glycoprotein** (not a lipoprotein) composed of two subunits. The **$\alpha$-subunit** is non-specific and identical to those of LH, FSH, and TSH. The **$\beta$-subunit** is unique and specific to hCG, which is why pregnancy tests and clinical assays target the $\beta$-subunit to avoid cross-reactivity with other hormones. **2. Analysis of Other Options** * **Option A (False Statement):** hCG is a **glycoprotein** (carbohydrate + protein), not a lipoprotein (lipid + protein). This is a common trap in biochemistry-based OBG questions. * **Option B (True Statement):** hCG is produced by the syncytiotrophoblast. It enters maternal circulation following implantation (which occurs 6–7 days after fertilization). Highly sensitive Radioimmunoassays (RIA) can detect it in maternal serum as early as **8–9 days post-conception**. * **Option C (False Statement):** hCG is secreted by the **syncytiotrophoblast** of the developing placenta, not the corpus luteum. In fact, the primary role of hCG is to *rescue* and maintain the corpus luteum, ensuring it continues to produce progesterone until the placenta takes over (luteal-placental shift). **3. NEET-PG High-Yield Pearls** * **Doubling Time:** In early pregnancy, hCG levels double every **48–72 hours**. * **Peak Levels:** hCG reaches its peak at **8–10 weeks** of gestation (approx. 100,000 mIU/mL) and then declines to a plateau. * **Clinical Utility:** Low levels for gestational age may indicate ectopic pregnancy or threatened abortion; abnormally high levels suggest **Molar pregnancy** or Multiple gestations. * **Biological Function:** It acts on LH receptors of the corpus luteum and is also involved in the stimulation of fetal Leydig cells for testosterone production.

Practice by Chapter

Endocrine Changes in Normal Pregnancy

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Thyroid Disorders in Pregnancy

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Diabetes in Pregnancy

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Adrenal Disorders in Pregnancy

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Pituitary Disorders in Pregnancy

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Hyperemesis Gravidarum

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Hormonal Regulation of Labor

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Pharmacokinetics of Hormones in Pregnancy

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Fetal Endocrine Development

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Placental Hormones

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