Hypothalamic and Pituitary Hormones — MCQs
A middle-aged male patient presents with protrusion of the chin, excessive sweating, impaired glucose tolerance, and enlargement of hands and feet. Which of the following is a growth hormone receptor antagonist used to treat this condition?
A middle aged man noticed that he can no longer fit in his shoes and that his jaw was protruding and phalanges were enlarged. These effects are likely to be mediated by
If blood supply to hypothalamus is interrupted through median eminence which hormone will have normal secretion?
Tolvaptan is used for:-
Which of the following leads to development of SIADH?
Which of the following is the drug of choice for the treatment of Syndrome of Inappropriate Antidiuretic Hormone secretion?
Suprasellar calcification with polyuria seen in -
Which sulfonylurea is used in the treatment of neurogenic diabetes insipidus?
A 47-year-old woman presents with complaints of nervousness and increased sensitivity to hot weather. She is diagnosed with hyperthyroidism and prescribed propylthiouracil. What is the principal mechanism by which this drug acts?
Gigantism is most commonly caused by:
Hypothalamic and Pituitary Hormones Indian Medical PG Practice Questions and MCQs
Question 1: A middle-aged male patient presents with protrusion of the chin, excessive sweating, impaired glucose tolerance, and enlargement of hands and feet. Which of the following is a growth hormone receptor antagonist used to treat this condition?
- A. Pegvisomant (Correct Answer)
- B. Olcegepant
- C. Cabergoline
- D. Octreotide
Explanation: ***Pegvisomant*** - **Pegvisomant** is a **growth hormone receptor antagonist** that binds to growth hormone receptors, preventing endogenous growth hormone from signaling and reducing IGF-1 levels. - It is specifically used in the treatment of **acromegaly**, a condition characterized by excessive growth hormone secretion, which aligns with the patient's symptoms of chin protrusion, excessive sweating, impaired glucose tolerance, and enlarged hands and feet. *Octreotide* - **Octreotide** is a **somatostatin analog** that works by inhibiting growth hormone secretion from the pituitary gland. - While used in acromegaly, it is not a growth hormone receptor antagonist, but rather reduces the production of growth hormone itself. *Cabergoline* - **Cabergoline** is a **dopamine agonist** primarily used to treat hyperprolactinemia by inhibiting prolactin secretion. - It can sometimes be used in acromegaly for patients with co-secretion of prolactin or those who are sensitive to its effects on growth hormone, but it is not a direct growth hormone receptor antagonist. *Olcegepant* - **Olcegepant** is a **calcitonin gene-related peptide (CGRP) receptor antagonist** developed for the treatment of migraine. - It has no known therapeutic role in the management of acromegaly or growth hormone-related disorders.
Question 2: A middle aged man noticed that he can no longer fit in his shoes and that his jaw was protruding and phalanges were enlarged. These effects are likely to be mediated by
- A. TRH
- B. ACTH
- C. TGF Beta
- D. IGF-1 (Correct Answer)
Explanation: ***IGF-1*** - The described symptoms (increased shoe size, jaw protrusion, enlarged phalanges) are characteristic of **acromegaly**, a condition caused by excessive growth hormone (GH) secretion in adults. - **Insulin-like Growth Factor 1 (IGF-1)** is primarily responsible for mediating the growth-promoting effects of GH on various tissues, leading to the clinical manifestations seen in this patient. *TRH* - **Thyrotropin-releasing hormone (TRH)** stimulates the release of thyroid-stimulating hormone (TSH) from the pituitary, which in turn regulates thyroid hormone production. - Excess TRH would lead to hyperthyroidism symptoms like weight loss, heat intolerance, and tachycardia, not acromegalic features. *ACTH* - **Adrenocorticotropic hormone (ACTH)** stimulates the adrenal glands to produce cortisol. - Excessive ACTH causes **Cushing's syndrome**, characterized by central obesity, moon facies, striae, and muscle weakness, which are different from the presented symptoms. *TGF Beta* - **Transforming growth factor beta (TGF-beta)** is a pleiotropic cytokine involved in cell growth, differentiation, apoptosis, and immune regulation. - While it plays a role in tissue remodeling and fibrosis, it is not the direct mediator of the generalized growth and skeletal changes seen in acromegaly.
Question 3: If blood supply to hypothalamus is interrupted through median eminence which hormone will have normal secretion?
- A. GH
- B. TSH
- C. Vasopressin (Correct Answer)
- D. Prolactin
Explanation: ***Vasopressin (ADH)*** - Vasopressin is synthesized in the **supraoptic and paraventricular nuclei** of the hypothalamus - It travels down **axons** (hypothalamic-hypophyseal tract) to the **posterior pituitary** where it is stored and released - Its secretion is **NOT dependent on the hypophyseal portal system** that passes through the median eminence - Interruption of the portal blood supply through the median eminence affects only the **anterior pituitary hormones** - Vasopressin secretion would remain **completely normal** as it bypasses the portal system entirely *Prolactin* - Prolactin is an anterior pituitary hormone under **tonic inhibition** by dopamine from the hypothalamus - Dopamine reaches the anterior pituitary via the **portal system through the median eminence** - Interruption of this blood supply would **block dopamine delivery**, resulting in **increased prolactin secretion** (not normal) - This is the classic "stalk effect" seen in pituitary stalk lesions *GH* - Growth Hormone requires **GHRH (Growth Hormone-Releasing Hormone)** stimulation from the hypothalamus - GHRH travels via the **portal system** to stimulate the anterior pituitary - Portal disruption prevents GHRH delivery → **Decreased GH secretion** *TSH* - Thyroid-Stimulating Hormone requires **TRH (Thyrotropin-Releasing Hormone)** stimulation - TRH travels via the **portal system** to the anterior pituitary - Portal disruption prevents TRH delivery → **Decreased TSH secretion**
Question 4: Tolvaptan is used for:-
- A. SIADH (Correct Answer)
- B. Von Willebrand disease
- C. Central DI
- D. Catecholamine resistant Shock
Explanation: ***SIADH*** - **Tolvaptan** is a **vasopressin V2 receptor antagonist** that promotes water excretion without affecting sodium, making it ideal for treating **euvolemic and hypervolemic hyponatremia** associated with SIADH. - In **syndrome of inappropriate antidiuretic hormone secretion (SIADH)**, there is excessive **ADH** leading to water retention and dilutional hyponatremia; tolvaptan effectively counters this by blocking vasopressin's action. *Von Willebrand disease* - This is a **bleeding disorder** caused by a deficiency or dysfunction of **von Willebrand factor**, treated with **desmopressin** or factor replacement, not tolvaptan. - Tolvaptan has no role in coagulation pathways or the management of bleeding disorders. *Central DI* - **Central diabetes insipidus (DI)** results from reduced **ADH production** by the hypothalamus or posterior pituitary, leading to excessive water loss. - It is treated with **desmopressin** (synthetic ADH) to replace the deficient hormone, which is the opposite effect of tolvaptan. *Catecholamine resistant Shock* - **Catecholamine-resistant shock** is characterized by persistent hypotension despite high doses of **vasopressors**. - Treatment often involves agents like **vasopressin** (not tolvaptan) or corticosteroids to improve vascular tone, as tolvaptan would worsen the hypotension by promoting diuresis.
Question 5: Which of the following leads to development of SIADH?
- A. Lung cancer
- B. Pituitary adenoma
- C. CNS disorders (Correct Answer)
- D. All of the options
Explanation: ***CNS disorders*** - Neurological conditions such as **stroke**, hemorrhage, infection, and trauma can cause inappropriate **ADH release** due to damage or irritation of the hypothalamus or posterior pituitary [2]. - This leads to increased water reabsorption and subsequent **hyponatremia** characteristic of SIADH [1]. *Lung cancer* - Certain types of **lung cancer**, particularly **small cell lung carcinoma (SCLC)**, are known to produce ADH ectopically, leading to SIADH. - This represents a **paraneoplastic syndrome**, where the tumor cells independently synthesize and secrete ADH. *Pituitary adenoma* - While pituitary adenomas can cause various endocrine dysfunctions, they are generally **not a direct cause of SIADH**. - **SIADH** typically results from unregulated ADH secretion rather than a primary pituitary tumor's overproduction of ADH itself. *All of the options* - Although **lung cancer** and **CNS disorders** are well-established causes of SIADH, **pituitary adenomas** are not a common or direct cause. - Therefore, choosing "all of the options" would be incorrect due to the inclusion of pituitary adenoma as a direct cause.
Question 6: Which of the following is the drug of choice for the treatment of Syndrome of Inappropriate Antidiuretic Hormone secretion?
- A. Demeclocycline (Correct Answer)
- B. Chlorpropamide
- C. Vasopressin
- D. Thiazide diuretics
Explanation: ***Demeclocycline*** - **Demeclocycline** is a **tetracycline antibiotic** that inhibits the action of ADH on the renal tubules, promoting excretion of water. - This effect helps to correct the **hyponatremia** and fluid retention seen in SIADH. - It is considered the **classic drug of choice** for chronic SIADH management, though newer agents like vaptans are increasingly used. *Chlorpropamide* - **Chlorpropamide** is a **sulfonylurea** medication primarily used for **type 2 diabetes mellitus** to stimulate insulin release. - It can **potentiate ADH action**, which would worsen SIADH rather than treat it. *Vasopressin* - **Vasopressin** (also known as ADH) is the **hormone** whose excessive secretion is the underlying problem in SIADH. - Administering vasopressin would **aggravate** the condition by increasing water reabsorption and worsening hyponatremia. *Thiazide diuretics* - **Thiazide diuretics** can **worsen hyponatremia** by impairing the kidney's ability to dilute urine and excrete free water. - This makes them **contraindicated in SIADH** management. - They are used in conditions like **hypertension** or paradoxically in **nephrogenic diabetes insipidus** (where they reduce urine output), but not for treating SIADH.
Question 7: Suprasellar calcification with polyuria seen in -
- A. Pinealoma
- B. Craniopharyngioma (Correct Answer)
- C. Langerhan cell histocytosis
- D. Medulloblastoma
Explanation: ***Craniopharyngioma*** - This benign tumor commonly arises from Rathke's pouch remnants and often causes **suprasellar calcification** visible on imaging [1]. - Its proximity to the pituitary stalk and hypothalamus can lead to **diabetes insipidus**, manifesting as **polyuria** and polydipsia [1]. *Pinealoma* - These tumors arise in the pineal region and are typically associated with symptoms like **Parinaud's syndrome** (upward gaze palsy) due to compression of the tectal plate. - Suprasellar calcification and polyuria are not characteristic features of pinealomas. *Langerhan cell histocytosis* - This systemic disease can affect various organs, including the central nervous system, and may cause **diabetes insipidus**. - However, **suprasellar calcification** is not a typical imaging finding; instead, focal lytic bone lesions are more common. *Medulloblastoma* - This is a highly malignant tumor typically found in the **cerebellum** (posterior fossa) of children. - It usually presents with symptoms of increased intracranial pressure and ataxia, and **suprasellar calcification or polyuria** are not associated features.
Question 8: Which sulfonylurea is used in the treatment of neurogenic diabetes insipidus?
- A. Glyburide
- B. Chlorpropamide (Correct Answer)
- C. Glipizide
- D. Tolbutamide
Explanation: ***Chlorpropamide*** - **Chlorpropamide** is the only sulfonylurea that has an **antidiuretic effect** and can enhance the action of **antidiuretic hormone (ADH)** by increasing the release of ADH and potentiating its action on the renal tubules. - This effect makes it useful in some cases of partial **neurogenic diabetes insipidus**, where there's still some ADH production. *Glyburide* - **Glyburide** is a second-generation sulfonylurea primarily used for **type 2 diabetes mellitus** to increase insulin secretion. - It does not have significant **antidiuretic properties** that would be beneficial in diabetes insipidus. *Glipizide* - **Glipizide** is another second-generation sulfonylurea, similar to glyburide, primarily used to stimulate **insulin release** from pancreatic beta cells in **type 2 diabetes**. - It lacks the specific mechanism of action required to treat **diabetes insipidus**. *Tolbutamide* - **Tolbutamide** is a first-generation sulfonylurea that also works by stimulating **insulin secretion** from the pancreas. - While it is a sulfonylurea, it does not possess the unique **antidiuretic properties** of chlorpropamide that are required for treating diabetes insipidus.
Question 9: A 47-year-old woman presents with complaints of nervousness and increased sensitivity to hot weather. She is diagnosed with hyperthyroidism and prescribed propylthiouracil. What is the principal mechanism by which this drug acts?
- A. Reducing the proteolysis of thyroglobulin.
- B. Inhibiting the binding of TSH to its receptor.
- C. Inhibiting the enzyme thyroid peroxidase, which reduces the synthesis of thyroid hormones. (Correct Answer)
- D. Altering the levels of reverse T3 (rT3) in the body.
Explanation: ***Inhibiting the enzyme thyroid peroxidase, which reduces the synthesis of thyroid hormones.*** - **Propylthiouracil (PTU)** is a **thionamide** drug that primarily acts by inhibiting the enzyme **thyroid peroxidase**. - Thyroid peroxidase is crucial for the **organification of iodide** and the **coupling of iodotyrosines** (MIT and DIT) to form T3 and T4, thus reducing the synthesis of thyroid hormones. *Inhibiting the binding of TSH to its receptor.* - This mechanism is characteristic of **TSH receptor antibodies**, which are a cause of hyperthyroidism (e.g., in Graves' disease), rather than the action of an antithyroid drug like PTU. - PTU works at the level of hormone synthesis within the thyroid gland, not at the receptor level for TSH. *Reducing the proteolysis of thyroglobulin.* - While thyroid hormones are stored as part of thyroglobulin, and their release involves proteolysis, this is not the **principal mechanism of action** for PTU. - The main effect of PTU is upstream, preventing the formation of the hormones themselves. *Altering the levels of reverse T3 (rT3) in the body.* - PTU does inhibit the **peripheral conversion of T4 to T3**, which can reduce overall T3 levels and increase rT3, but this is a **secondary mechanism**. - The primary and most significant action for reducing hyperthyroid symptoms is the direct inhibition of thyroid hormone synthesis within the gland.
Question 10: Gigantism is most commonly caused by:
- A. Chromosomal abnormalities
- B. Pituitary adenomas (Correct Answer)
- C. Parathyroid disorders
- D. Thyroid disorders
Explanation: Pituitary adenomas - Gigantism is characterized by excessive growth and height, primarily caused by hypersecretion of growth hormone (GH) before the fusion of epiphyseal plates [1]. - The most common cause of sustained GH hypersecretion leading to gigantism is a pituitary adenoma, a benign tumor of the pituitary gland's somatotroph cells [2], [3]. Chromosomal abnormalities - While some genetic conditions can cause tall stature (e.g., Klinefelter syndrome), they are not the primary cause of gigantism, which is specifically related to excessive GH production. - Conditions like Marfan syndrome may cause tall stature but do not involve GH excess or pituitary adenomas. Parathyroid disorders - These primarily affect calcium and phosphate metabolism, leading to conditions like hypercalcemia or hypocalcemia. - They do not directly cause excessive growth hormone secretion or gigantism. Thyroid disorders - Hyperthyroidism can cause increased metabolic rate and weight loss, but it does not lead to the massive skeletal overgrowth seen in gigantism. - Hypothyroidism in childhood can cause dwarfism or stunted growth, which is the opposite of gigantism.
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