Endocrine Pharmacology — MCQs

An elderly hypothyroid patient with chronic gastrointestinal complaints is being treated with triiodothyronine (T3) rather than thyroxine replacement because the former drug has better gastrointestinal absorption. When compared with no medication, triiodothyronine should have which of the following effects on serum levels of TSH, T3, and T4?

Q677

All are used in the treatment of hot flushes except

Q678

Basanti devi, a 45-year-old woman, presents with hot flushes after cessation of menstruation. Hot flushes can be relieved by administration of the following agents:

Q679

A 60 year old woman is seen at an emergency room after she fractures the neck of her right femur during a minor fall. Radiologic studies demonstrate a generalized loss of bone mass. Exogenous therapy with which of the following hormones would have been most likely to slow or prevent the patient's bone disease?

Q680

Most serious adverse effect of Raloxifene is:

Endocrine Pharmacology Indian Medical PG Practice Questions and MCQs

Question 671: The success of estrogen and estrogen-like drugs in combating osteoporosis in postmenopausal women may indicate that estrogen:

A. Increases the activity of bone-resorbing cells
B. Decreases the activity of bone-resorbing cells (Correct Answer)
C. Prevents the mineralization of bone during turnover
D. Reduces the activity of bone-forming cells

Explanation: ***Decreases the activity of bone-resorbing cells*** - **Estrogen** plays a crucial role in maintaining **bone density** by inhibiting the activity of **osteoclasts**, which are the cells responsible for **bone resorption**. - In postmenopausal women, the decline in estrogen levels leads to increased osteoclast activity and accelerated **bone loss**, hence the effectiveness of estrogen therapy. *Increases the activity of bone-resorbing cells* - An increase in **bone-resorbing cell** (osteoclast) activity would lead to further **bone loss** and exacerbate osteoporosis, contrary to the observed therapeutic effect of estrogen. - Estrogen's protective role in **bone health** is primarily through its inhibitory effect on osteoclasts. *Prevents the mineralization of bone during turnover* - This option describes a process that would lead to **osteomalacia** or **rickets**, where new bone matrix fails to mineralize adequately. - Estrogen's action is not primarily on mineralization but on the **balance between bone formation and resorption**. *Reduces the activity of bone-forming cells* - Reducing the activity of **bone-forming cells** (osteoblasts) would also lead to reduced bone density and worsen osteoporosis. - While estrogen has complex effects, its main therapeutic benefit in osteoporosis is to **slow down bone breakdown**, not to reduce bone formation.

Question 672: The established benefits of estrogen replacement therapy in menopausal women include a reduction in all of the following EXCEPT

A. Hot flushes
B. Mood depression (Correct Answer)
C. Atrophic vaginitis
D. Osteoporosis

Explanation: ***Mood depression*** - While some women may experience mood changes during menopause, estrogen replacement therapy does not consistently or significantly reduce **mood depression**. - The relationship between estrogen and mood is complex, and depression in menopausal women often has **multifactorial causes** beyond hormonal changes. *Hot flushes* - Estrogen replacement therapy is highly effective in alleviating **vasomotor symptoms** such as hot flushes and night sweats [1, 2]. - These symptoms are directly linked to declining estrogen levels. *Atrophic vaginitis* - Estrogen therapy effectively treats **genitourinary syndrome of menopause** (GSM), including symptoms of atrophic vaginitis. - It restores the **vaginal epithelium**, increasing lubrication and reducing dryness, itching, and dyspareunia. *Osteoporosis* - Estrogen plays a crucial role in **bone density maintenance** and its decline at menopause contributes to accelerated bone loss. - Estrogen replacement therapy is a known treatment to prevent and manage **postmenopausal osteoporosis** by reducing bone turnover [1].

Question 673: Which of the following drugs is available as a nasal spray formulation?

A. Calcitonin (Correct Answer)
B. Oestrogen
C. Calcium
D. PTH

Explanation: ***Calcitonin*** - **Calcitonin salmon** is available as a nasal spray (Miacalcin®) and is used in the treatment of **postmenopausal osteoporosis**. - Nasal administration provides an alternative to injection for patients who may have difficulty with subcutaneous or intramuscular routes. *Oestrogen* - **Oestrogen** is primarily available in oral, transdermal patch, vaginal cream, or injectable formulations. - While some hormonal therapies are available as nasal sprays (e.g., certain GnRH agonists), **oestrogen itself is not typically administered via this route** for routine indications. *Calcium* - **Calcium** is a mineral supplement predominantly available in oral formulations (e.g., tablets, chewables, liquids). - It is not typically formulated as a nasal spray for systemic absorption or treatment of calcium deficiency. *PTH* - **Teriparatide**, a recombinant form of **parathyroid hormone (PTH)**, is administered via subcutaneous injection. - While it has potent effects on bone, it is not available as a nasal spray due to challenges with absorption and stability.

Question 674: Drug not used in SIADH is:

A. 3% NaCl
B. Desmopressin (Correct Answer)
C. Demeclocycline
D. Tolvaptan

Explanation: ***Desmopressin*** - **Desmopressin** is a synthetic analog of **ADH** (antidiuretic hormone), which is **excessive in SIADH**. - Administering desmopressin would worsen SIADH by further increasing water reabsorption and diluting serum sodium. *3% NaCl* - **Hypertonic saline** (like 3% NaCl) is used in SIADH, particularly for severe hyponatremia, to **raise serum sodium levels** rapidly. - It works by increasing the osmotic gradient, drawing water out of cells and into the extracellular space for excretion. *Demeclocycline* - **Demeclocycline** is a **tetracycline antibiotic** that can induce **nephrogenic diabetes insipidus**. - This effect makes the kidneys less responsive to ADH, thus reducing water reabsorption and helping to correct hyponatremia in chronic SIADH. *Tolvaptan* - **Tolvaptan** is an **ADH receptor antagonist** (Aquaretic). - It blocks the action of ADH in the kidneys, leading to increased water excretion without affecting electrolyte excretion, thereby raising serum sodium levels.

Question 675: Drug of choice for precocious puberty:

A. GnRH agonists (Correct Answer)
B. Tamoxifen
C. Cyproterone acetate
D. Medroxyprogesterone

Explanation: ***GnRH agonists*** - **GnRH agonists** are the drug of choice for central precocious puberty as they **downregulate GnRH receptors** on the pituitary. - This downregulation leads to a **reduction in gonadotropin release** (LH and FSH), thereby suppressing sex hormone production and halting pubertal progression. *Tamoxifen* - **Tamoxifen** is a **selective estrogen receptor modulator (SERM)** primarily used in **breast cancer treatment**. - While it has **antiestrogenic effects** in breast tissue, it has **estrogenic effects** in other tissues and would not be appropriate for treating precocious puberty as it **does not suppress the central hypothalamic-pituitary-gonadal axis** and may have unpredictable effects on pubertal development. *Cyproterone acetate* - **Cyproterone acetate** is an **antiandrogen** with some progestational effects, mainly used to treat conditions caused by excess androgens, such as hirsutism or severe acne. - While it can suppress some aspects of sexual development by blocking androgen receptors, it **does not directly inhibit the central pubertal cascade** in the same way GnRH agonists do. *Medroxyprogesterone* - **Medroxyprogesterone** is a **progestin** that can suppress gonadotropin release in certain contexts, primarily in managing endometrial hyperplasia or contraception. - It is sometimes used in specific forms of precocious puberty (e.g., peripheral) but is **not the first-line treatment for central precocious puberty** as GnRH agonists are more effective at suppressing the entire hypothalamic-pituitary-gonadal axis.

Question 676: An elderly hypothyroid patient with chronic gastrointestinal complaints is being treated with triiodothyronine (T3) rather than thyroxine replacement because the former drug has better gastrointestinal absorption. When compared with no medication, triiodothyronine should have which of the following effects on serum levels of TSH, T3, and T4?

A. Decreased TSH, increased T3, and decreased T4 (Correct Answer)
B. Decreased TSH, decreased T3, and decreased T4
C. Increased TSH, decreased T3, and decreased T4
D. Decreased TSH, increased T3, and increased T4

Explanation: ***Decreased TSH, increased T3, and decreased T4*** - Administration of exogenous **T3** directly increases serum **T3** levels, which then exerts negative feedback on the pituitary gland, leading to a **decrease in TSH** secretion [1]. - Reduced TSH stimulation of the thyroid gland, combined with the fact that T3 (rather than T4) is being provided, results in **decreased endogenous T4** production and release. *Decreased TSH, decreased T3, and decreased T4* - While TSH and T4 would decrease due to negative feedback and reduced thyroid stimulation, therapeutic administration of **T3** would lead to **increased T3** levels, not decreased. - This option incorrectly suggests a decrease in the directly administered hormone. *Increased TSH, decreased T3, and decreased T4* - **Increased TSH** is characteristic of untreated or under-treated hypothyroidism because of the lack of negative feedback from low thyroid hormones; exogenous T3 would correct this, leading to decreased TSH. - Therapeutically administered **T3** would cause an **increase in T3** levels, not a decrease. *Decreased TSH, increased T3, and increased T4* - While TSH would decrease and T3 would increase, **T4 levels would typically decrease** because the thyroid gland's endogenous production is suppressed by the decreased TSH, and no exogenous T4 is being provided. - This option incorrectly assumes that T4 levels would increase despite TSH suppression.

Question 677: All are used in the treatment of hot flushes except

A. Gabapentin
B. Clonidine
C. Tamoxifen (Correct Answer)
D. Venlafaxine

Explanation: ***Tamoxifen*** - While Tamoxifen is an **anti-estrogen** used in breast cancer treatment, it can actually **cause or worsen hot flushes** as a side effect due to its estrogen receptor modulating effects in the hypothalamus. - It does not alleviate hot flushes and is therefore not used in their treatment in the general sense. *Gabapentin* - **Gabapentin**, an anticonvulsant, is often used off-label to treat hot flushes, particularly in women who cannot or prefer not to use hormone therapy. - It works by reducing the excitability of thermoregulatory neurons in the hypothalamus. *Clonidine* - **Clonidine**, an alpha-2 adrenergic agonist, can be used to treat hot flushes, especially in menopausal women. - It acts on the central nervous system to reduce the frequency and severity of vasomotor symptoms. *Venlafaxine* - **Venlafaxine**, a serotonin-norepinephrine reuptake inhibitor (SNRI), is a recognized non-hormonal treatment for hot flushes. - It is thought to work by modulating neurotransmitter levels that influence the thermoregulatory center in the brain.

Question 678: Basanti devi, a 45-year-old woman, presents with hot flushes after cessation of menstruation. Hot flushes can be relieved by administration of the following agents:

A. Ethinyl estradiol (Correct Answer)
B. Fluoxymesterone
C. Testosterone
D. Danazol

Explanation: ***Ethinyl estradiol*** - **Ethinyl estradiol** is a synthetic estrogen that effectively replaces the declining estrogen levels in menopause, directly alleviating **vasomotor symptoms** like hot flashes [1, 2]. - Estrogen replacement therapy is a primary treatment for moderate to severe **menopausal symptoms** [2]. *Fluoxymesterone* - **Fluoxymesterone** is an androgen (male hormone), primarily used for male hypogonadism and certain types of breast cancer, and is not indicated for relieving menopausal hot flashes. - It would not address the underlying **estrogen deficiency** responsible for hot flashes. *Testosterone* - While testosterone levels do decline in women with age, it is not the primary hormone responsible for hot flashes and is generally used for **libido issues** or low energy, not vasomotor symptoms. - Administering testosterone could lead to **virilizing side effects**, such as hirsutism or deepening of the voice. *Danazol* - **Danazol** is a synthetic androgen and an antigonadotropin used to treat conditions like endometriosis and fibrocystic breast disease. - It acts by suppressing estrogen production and would likely **worsen hot flashes** rather than relieve them.

Question 679: A 60 year old woman is seen at an emergency room after she fractures the neck of her right femur during a minor fall. Radiologic studies demonstrate a generalized loss of bone mass. Exogenous therapy with which of the following hormones would have been most likely to slow or prevent the patient's bone disease?

A. Epinephrine
B. Thyroxine
C. Cortisol
D. Estrogen (Correct Answer)

Explanation: ***Estrogen*** - **Estrogen deficiency** post-menopause is a primary cause of **osteoporosis** in women due to increased osteoclast activity and bone resorption. - **Exogenous estrogen therapy** could have helped prevent bone loss by inhibiting osteoclast activity and promoting osteoblast function. *Epinephrine* - **Epinephrine** is a catecholamine primarily involved in the **fight-or-flight response**, affecting cardiovascular function and metabolism. - It does not have a direct therapeutic role in preventing **generalized bone mass loss** or treating osteoporosis. *Thyroxine* - **Thyroxine (thyroid hormone)**, especially in excess, can actually accelerate bone turnover and lead to **bone loss** and increased fracture risk. - It is not used to prevent osteoporosis; managing thyroid dysfunction is crucial to bone health. *Cortisol* - **Cortisol** is a glucocorticoid that, when in excess (e.g., in Cushing's syndrome or long-term steroid use), can cause **osteoporosis** by inhibiting bone formation and increasing bone resorption. - Therefore, exogenous cortisol would exacerbate, not prevent, the patient's bone disease.

Question 680: Most serious adverse effect of Raloxifene is:

A. Hot flashes
B. Leg cramps
C. Stroke
D. Venous thromboembolism (Correct Answer)

Explanation: ***Venous thromboembolism*** - **Raloxifene** is a selective estrogen receptor modulator (SERM) that acts as an estrogen agonist in bone but an antagonist in breast and uterine tissues. - It carries a **BLACK BOX WARNING** for increased risk of **venous thromboembolism (VTE)**, including **deep vein thrombosis (DVT)** and **pulmonary embolism (PE)**. - VTE is the **most serious and life-threatening adverse effect**, with a 3-fold increased risk compared to placebo. - **Contraindicated** in patients with active or history of VTE. *Hot flashes* - Very common side effect (occurs in ~25% of patients) due to estrogen antagonist effects. - Bothersome but not life-threatening. - May lead to discontinuation of therapy but does not pose serious health risk. *Leg cramps* - Common side effect of raloxifene, often occurring at night. - Inconvenient but not serious or life-threatening. - Generally manageable with symptomatic treatment. *Stroke* - Raloxifene also increases stroke risk (included in FDA black box warning). - However, in the context of SERM therapy and osteoporosis treatment, **VTE** is the **most emphasized serious adverse effect** in medical education. - Both VTE and stroke are serious, but VTE risk is more consistently highlighted as the primary concern.

Practice by Chapter

Hypothalamic and Pituitary Hormones

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Thyroid Drugs and Antithyroid Agents

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Insulin and Oral Hypoglycemic Agents

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Adrenocorticosteroids

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Sex Hormones: Estrogens and Progestins

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Androgens and Anabolic Steroids

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Hormonal Contraceptives

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Drugs Affecting Calcium Metabolism

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Drugs for Osteoporosis

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Pharmacological Management of Obesity

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