Pharmacokinetics of Hormones in Pregnancy — MCQs
Thyroxine binding globulin (TBG) is increased in:
The role of human placental lactogen is :
All are cardiovascular system changes in pregnancy except.
Which of the following hormones will be affected most after the change in sex hormone binding globulin?
The following changes occur in the urinary system in pregnancy except:
Heat-stable alkaline phosphatase in pregnancy is primarily derived from which source?
All of the following are physiological changes that occur during pregnancy, except which of the following?
Which of the following endocrinological conditions may be associated with hydatidiform mole: 46,XX?
Corpus luteum in pregnancy is maintained by which hormone?
Which hormone is secreted by the placenta?
Pharmacokinetics of Hormones in Pregnancy Indian Medical PG Practice Questions and MCQs
Question 1: Thyroxine binding globulin (TBG) is increased in:
- A. Pregnancy (Correct Answer)
- B. Cancer chemotherapy
- C. Nephrotic syndrome
- D. Glucocorticoid therapy
Explanation: ***Pregnancy*** - Estrogen levels are elevated during **pregnancy**, which leads to an increase in the synthesis of **TBG** by the liver. - Increased TBG binds more thyroid hormone, reducing free thyroid hormone levels, which then stimulates the thyroid gland to produce more. *Cancer chemotherapy* - Many **chemotherapeutic agents** can damage the liver or interfere with protein synthesis, potentially leading to a *decrease* in TBG and other plasma proteins. - Chemotherapy can also induce **hypothyroidism** directly or indirectly, which may alter thyroid hormone binding. *Nephrotic syndrome* - **Nephrotic syndrome** is characterized by significant proteinuria, where plasma proteins, including **TBG**, are lost through the kidneys in the urine. - This leads to a *decrease* in serum TBG levels, which can affect total thyroid hormone measurements but typically does not cause overt thyroid dysfunction due to compensatory mechanisms. *Glucocorticoid therapy* - **Glucocorticoids** (e.g., prednisone, dexamethasone) are known to *decrease* the hepatic synthesis of **TBG**. - This reduction in TBG can lead to lower total thyroid hormone levels without necessarily indicating thyroid gland dysfunction, as free thyroid hormone levels often remain normal.
Question 2: The role of human placental lactogen is :
- A. Stimulate milk production
- B. Promotes growth of breast for lactation.
- C. Supports fetal growth and development. (Correct Answer)
- D. Provide fetal nutrition by antagonizing the action of insulin in maternal circulation, breakdown of fats and proteins and transport of fatty acids and amino acids from maternal to fetal circulation.
Explanation: ***Supports fetal growth and development.*** - Human placental lactogen (hPL) acts as a **growth hormone** for the fetus, primarily by altering maternal metabolism to favor fetal nutrient supply. - It increases **maternal insulin resistance**, leading to higher maternal glucose and free fatty acids, which are then shunted to the fetus, supporting its growth and development. *Stimulate milk production* - **Prolactin**, secreted by the anterior pituitary, is the primary hormone responsible for stimulating milk production (lactogenesis). - While hPL has some structural similarity to growth hormone and prolactin, its primary role is not to directly stimulate milk production during pregnancy; rather, it prepares the breasts. *Promotes growth of breast for lactation.* - hPL, along with **estrogen** and **progesterone**, contributes to the **mammary gland development** during pregnancy, preparing the breasts for lactation. - However, its direct role is more about **mammary gland proliferation and differentiation** rather than initiation of milk production. *Provide fetal nutrition by antagonizing the action of insulin in maternal circulation, breakdown of fats and proteins and transport of fatty acids and amino acids from maternal to fetal circulation.* - This is a highly detailed and largely accurate description of *how* hPL supports fetal growth and development, making it a mechanism rather than the primary, concise role. - It describes the metabolic changes induced by hPL, which ultimately lead to the **support of fetal growth and development**.
Question 3: All are cardiovascular system changes in pregnancy except.
- A. Increase in blood volume
- B. Increase in heart rate
- C. Increase in peripheral resistance (Correct Answer)
- D. Increase in cardiac output
Explanation: ***Increase in peripheral resistance*** - During normal pregnancy, **peripheral vascular resistance actually decreases** due to the effects of hormones like progesterone and the presence of the low-resistance uteroplacental circulation. - This decrease in resistance helps accommodate the increased blood volume and cardiac output. *Increase in cardiac output* - **Cardiac output increases significantly** during pregnancy (by 30-50%) to meet the metabolic demands of the growing fetus and maternal tissues. - This is primarily achieved through an increase in both stroke volume and heart rate. *Increase in blood volume* - **Blood volume increases substantially** (by 30-50%) during pregnancy, with plasma volume increasing more than red blood cell mass. - This expansion supports the increased cardiac output and placental perfusion. *Increase in heart rate* - **Heart rate increases** during pregnancy, typically by 10-20 beats per minute, contributing to the overall increase in cardiac output. - This physiological adaptation helps maintain adequate circulation.
Question 4: Which of the following hormones will be affected most after the change in sex hormone binding globulin?
- A. Testosterone (Correct Answer)
- B. Progesterone
- C. DHEA
- D. Estrogen
Explanation: ***Testosterone*** - **Sex hormone-binding globulin (SHBG)** binds primarily to **testosterone** (and dihydrotestosterone) with **high affinity**. - SHBG has approximately **5 times greater affinity** for testosterone compared to estradiol. - A change in SHBG levels will significantly impact the proportion of **free (biologically active) testosterone** available in the circulation, thus affecting its overall function and measurement. - This makes testosterone the hormone **most affected** by changes in SHBG levels. *Progesterone* - **Progesterone** is primarily bound to **albumin** and **corticosteroid-binding globulin (CBG)**, not SHBG. - Therefore, changes in SHBG would have minimal direct impact on progesterone levels or its bioavailability. *DHEA* - **Dehydroepiandrosterone (DHEA)** is mostly bound to **albumin** in the blood. - Its binding to SHBG is negligible, making changes in SHBG irrelevant to its overall circulating levels or activity. *Estrogen* - **Estrogen (estradiol)** also binds to SHBG, but with **significantly lower affinity** than testosterone (approximately 5-fold less). - While affected by SHBG changes, the impact is less pronounced than on testosterone due to the lower binding affinity and its additional binding to albumin.
Question 5: The following changes occur in the urinary system in pregnancy except:
- A. Increased RBF
- B. Increased GFR
- C. Increased activity of ureters (Correct Answer)
- D. Hypertrophy of bladder musculature
Explanation: ***Increased activity of ureters*** - Ureters actually experience **decreased peristaltic activity** and **dilation** during pregnancy due to hormonal influences (progesterone) and mechanical compression. - This leads to **urinary stasis** and an increased risk of urinary tract infections, a common complication of pregnancy. *Increased RBF* - **Renal blood flow (RBF)** significantly **increases** during pregnancy, primarily due to vasodilation induced by hormones like relaxin and nitric oxide. - This increase in RBF is essential to accommodate the increased metabolic demands and waste product excretion during pregnancy. *Increased GFR* - **Glomerular filtration rate (GFR)** also **increases** by 30-50% during pregnancy, reflecting the increased RBF and the need to filter a larger volume of plasma. - This elevated GFR can lead to lower serum creatinine and urea levels compared to the non-pregnant state. *Hypertrophy of bladder musculature* - The **bladder musculature undergoes hypertrophy** during pregnancy as a physiological adaptation to accommodate the growing uterus and maintain bladder function. - This hypertrophy helps the bladder withstand increased pressure and prepare for the demands of labor and delivery.
Question 6: Heat-stable alkaline phosphatase in pregnancy is primarily derived from which source?
- A. The placenta (Correct Answer)
- B. Maternal liver
- C. Fetal liver
- D. Maternal bone
Explanation: ***The placenta*** - The **placenta** is the primary source of heat-stable alkaline phosphatase (HSAP) during pregnancy. This specific isoform is distinct from other alkaline phosphatase isoforms. - Increased levels of HSAP are observed in maternal serum throughout pregnancy, reflecting **placental metabolic activity** and growth. - HSAP levels typically **rise progressively** from the first trimester and peak near term, serving as a marker of **placental function**. *Maternal liver* - The maternal liver produces **liver-specific alkaline phosphatase**, which is **not heat-stable**. - While liver ALP levels may fluctuate slightly in pregnancy, they are not the primary source of the heat-stable form. - Liver ALP is inactivated by heating at 56°C, unlike the placental isoform. *Fetal liver* - The fetal liver produces **alkaline phosphatase**, but this is not released into the maternal circulation in significant amounts as **heat-stable ALP**. - Fetal contribution to maternal serum **heat-stable ALP** is negligible compared to the placenta. - The placental barrier prevents significant transfer of fetal enzymes to maternal blood. *Maternal bone* - Maternal bone produces **bone-specific alkaline phosphatase**, which is also **not heat-stable**. - Bone ALP may increase during pregnancy due to skeletal remodeling, but it represents a different isoform. - Bone ALP can be distinguished from placental ALP by heat stability testing and electrophoresis.
Question 7: All of the following are physiological changes that occur during pregnancy, except which of the following?
- A. Decrease in renal plasma flow (Correct Answer)
- B. Increase in cardiac output
- C. Increase in glomerular filtration rate
- D. Increase in blood volume
Explanation: ***Decrease in renal plasma flow*** - This statement is incorrect because **renal plasma flow actually increases** significantly during pregnancy due to vasodilation. - The increased renal plasma flow contributes to the elevated **glomerular filtration rate** observed in pregnant women. *Increase in cardiac output* - **Cardiac output increases by 30-50%** during pregnancy to meet the metabolic demands of the growing fetus and maternal tissues. - This increase is primarily due to an increase in both **heart rate** and **stroke volume**. *Increase in glomerular filtration rate* - The **glomerular filtration rate (GFR) increases by 30-50%** during pregnancy, leading to increased renal clearance of waste products. - This physiologic change is partly due to the **increased renal plasma flow** and changes in renal hemodynamics. *Increase in blood volume* - **Blood volume increases by 30-50%** during pregnancy, with a proportionally greater increase in plasma volume compared to red blood cell mass. - This expansion in blood volume is crucial for meeting the demands of the uteroplacental circulation and protecting against hemorrhage during delivery.
Question 8: Which of the following endocrinological conditions may be associated with hydatidiform mole: 46,XX?
- A. Hypothyroidism
- B. Diabetes
- C. Hyperprolactinemia
- D. Hyperthyroidism (Correct Answer)
Explanation: ***Hyperthyroidism*** - A **complete hydatidiform mole** produces very high levels of **human chorionic gonadotropin (hCG)**, which has a structural similarity to **thyroid-stimulating hormone (TSH)**. - This **hCG** can bind to **TSH receptors** on the thyroid gland, stimulating **thyroid hormone production** and leading to **hyperthyroidism**. *Hypothyroidism* - **Hypothyroidism** is characterized by **low thyroid hormone levels** and is not directly induced by the hormonal changes associated with a hydatidiform mole. - While pregnancy can sometimes unmask or worsen hypothyroidism, it is not a direct endocrinological consequence of a molar pregnancy. *Diabetes* - **Diabetes mellitus** is a metabolic disorder characterized by **high blood glucose**, commonly associated with insulin resistance or deficiency. - There is no direct endocrinological link between **hydatidiform mole** and the development of diabetes. *Hyperprolactinemia* - **Hyperprolactinemia** is characterized by **elevated prolactin levels**, often leading to menstrual irregularities and galactorrhea. - While pregnancy itself causes an increase in prolactin, a hydatidiform mole does not specifically induce pathological **hyperprolactinemia**.
Question 9: Corpus luteum in pregnancy is maintained by which hormone?
- A. LH
- B. FSH
- C. hCG (Correct Answer)
- D. Progesterone
Explanation: ***hCG (Human Chorionic Gonadotropin)*** - **hCG** is produced by the **syncytiotrophoblast** of the developing embryo shortly after implantation - It acts as an **LH analog**, binding to LH receptors on the corpus luteum - hCG **rescues the corpus luteum** from degeneration, maintaining progesterone production throughout early pregnancy - The corpus luteum remains functional until approximately **10-12 weeks of gestation**, when the placenta takes over steroidogenesis - This is the **correct answer** for maintenance of corpus luteum **in pregnancy** *LH (Luteinizing Hormone)* - LH maintains the corpus luteum in **non-pregnant menstrual cycles** for approximately 14 days - In **pregnancy**, LH levels actually **decline** and hCG takes over this function - While LH is responsible for initial corpus luteum formation and function, it does **not** maintain the corpus luteum during pregnancy *FSH (Follicle-Stimulating Hormone)* - FSH primarily stimulates **follicular development and maturation** in the ovary - It has **no direct role** in corpus luteum maintenance in either pregnant or non-pregnant states *Progesterone* - Progesterone is the **product** secreted by the corpus luteum, not the hormone that maintains it - It is essential for maintaining the **decidualized endometrium** and supporting early pregnancy - Progesterone does not act to maintain the corpus luteum itself
Question 10: Which hormone is secreted by the placenta?
- A. GnRH
- B. FSH
- C. hCG (Correct Answer)
- D. LH
Explanation: ***hCG*** - **Human Chorionic Gonadotropin (hCG)** is produced by the **syncytiotrophoblast** of the placenta shortly after implantation. - Its primary role is to maintain the **corpus luteum**, ensuring continued production of **progesterone** to support the pregnancy. *GnRH* - **Gonadotropin-releasing hormone (GnRH)** is secreted by the **hypothalamus** in the brain, not the placenta. - It stimulates the pituitary gland to release FSH and LH. *FSH* - **Follicle-stimulating hormone (FSH)** is produced by the **anterior pituitary gland**. - It plays a crucial role in ovarian follicular development in females and spermatogenesis in males. *LH* - **Luteinizing hormone (LH)** is also secreted by the **anterior pituitary gland**. - Its functions include triggering ovulation in females and stimulating testosterone production in males.
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